Herbs & Botanicals · Traditional herb with cancer-risk compounds
Calamus
Acorus calamus · also called Sweet flag, Vacha (Ayurveda)
Calamus, or sweet flag, is a marsh plant whose rhizome (underground stem) is used in Ayurveda, where it is called Vacha, and in other traditional medicine for digestion and memory. Almost no human trials exist, so the evidence for benefit is traditional or from lab and animal work. Most important: its main compounds, the asarones, caused liver cancer in rodents, and US law treats added calamus in food as adulterated.
General information, not medical advice. Last substantive update · Not medically reviewed. A named clinician has not signed off on this page. How this page is made
About Calamus
Calamus (sweet flag, Vacha) is the rhizome of Acorus calamus. The European Medicines Agency says its asarone compounds are genotoxic and cause liver cancer in rodents. The US treats added calamus in food as adulterated. Asarone content varies from none to very high depending on plant type. Human research on benefits is essentially absent.
Why the plant type matters
Calamus comes in diploid, triploid and tetraploid forms. In the EMA table the diploid American type had no asarone detected, the triploid type 9 to 19% of rhizome oil, and the tetraploid Asian type 85 to 95%. The triploid type had even more in its leaf oil (50 to 65%).
A 2005 lab study found a diploid type completely lacking beta-asarone and a triploid extract with 11%. Growing conditions can also change the levels of hazardous compounds in plants. A product label rarely says which type it contains. The EMA advised that diploid types should always be preferred.
A 2025 bacterial mutation test of an Indian rhizome and pure beta-asarone was negative, but the authors themselves ask for long-term cancer tests.
Medicines and other cautions
No human interaction study was found. Animals showed a blood-clot-slowing effect, and test-tube work showed the extract can block the liver enzymes CYP3A4 and CYP2D6. CYP3A4 is also the main enzyme that turns alpha-asarone into reactive products in the lab.
Sedative effects are described in rats. If you take blood thinners, sedatives or other prescription medicine, ask your doctor or pharmacist before any calamus product.
No pesticide or heavy-metal testing of calamus products was found.
What regulators say
United States: 21 CFR 189.110 says food containing any added calamus, oil of calamus or extract of calamus is deemed adulterated, based on a 1968 order. The section read covers food only, so we did not verify any wording on drugs or supplements.
European Union and UK: the EMA gave a 2005 statement advising asarone be kept to a minimum, diploid types be preferred, and a temporary exposure limit of about 115 microgram a day be accepted until a full assessment. The flavourings regulation (UK-published copy read) bars adding beta-asarone as such to food and caps it at 1.0 mg/kg in alcoholic drinks; the EU copy could not be opened.
Not found: NCCIH, Health Canada, LiverTox, LactMed, and an HMPC monograph.
What it is
Calamus is Acorus calamus, family Acoraceae. The rhizome is the part used, as powder, extract or essential oil. In Ayurveda it is Vacha and is traditionally given for brain, gut and breathing complaints.
The Chinese herb shi chang pu is usually Acorus tatarinowii, a related plant not covered on this page. Naming databases disagree on how closely they are related, and DNA tests exist to tell the Acorus species apart.
How strong is the evidence for possible uses?
Almost none of it is from people. The traditional digestive and memory uses are supported by tradition and by lab and animal studies, mostly of isolated asarones. Reviews list sedative, anticonvulsant, antidepressant-like and metabolic effects in animals.
The only human study found used a homeopathic dilution in 321 people with no control group, so it says nothing about the herb. Overall certainty is insufficient for every use.
At a glance
Traditional uses history, not proof
- Stomach cramps, colic, indigestion and dysentery in Ayurveda, Unani, Siddha and Chinese tradition (2014 review).
- Brain and memory tonic, including for infants, as Vacha in Ayurveda (2020 and 2025 papers).
- Asthma, bronchitis and cough, worm treatment and as a tonic (EMA 2005).
Studied for research
- Memory and thinking: insufficient evidence (traditional and animal only)
- Mood, sleepiness and seizures: insufficient (animal only)
- Digestion and breathing: insufficient (traditional use only)
- Blood sugar, blood fats, inflammation: insufficient (lab and animal)
- A homeopathic version in one uncontrolled study: very low
Main compounds
- Beta-asarone, a carcinogenic compound whose amount varies from none to very high by plant type
- Alpha-asarone and gamma-asarone
- Sesquiterpenes such as acorone
Common forms
- Dried rhizome powder
- Extract or tincture
- Essential oil
- Ayurvedic purified (Shodhana) rhizome
Research links: EMA public statement on herbal medicinal products containing asarone (2005) · 21 CFR 189.110: Calamus and its derivatives · Asarone isomers: current status of toxicological evaluation (J Appl Toxicol 2021) · Bioanalytical investigation of asarone in calamus oil intoxications (2009) · Research Library · Genes & Biomarkers Library
The plant and its history
- Accepted scientific name
- Acorus calamus
- Naming authority
- L.
- Synonyms
- Name: Acorus aromaticus Gueldenst.; Status: synonym; Name: Acorus vulgaris Simonk.; Status: synonym; Name: Calamus aromaticus Garsault; Status: synonym; Name: Calamus aromaticus Ledeb.; Status: synonym
- Common names
- Calamus (English); Sweet flag (English); Vacha (Sanskrit / Hindi (Ayurveda))
- Botanical family
- Acoraceae
- Classification
- Plantae > Tracheophyta > Liliopsida > Acorales > Acoraceae > Acorus > Acorus calamus
- Native range
- Not confirmed from a source read. A 2005 abstract calls it indigenous to Central Asia and Eastern Europe; a 2024 botany paper describes diploid, triploid and tetraploid forms in Kazakhstan.
- Habitat
- Aromatic marsh herb with a rhizome (the part used). Habitat detail was not checked.
- What the plant looks like
- Roots: Rhizome is the medicinal part.; Stems: Not checked.; Leaves: Leaves also carry essential oil (EMA table).; Flowers: Not checked.; Fruit: The triploid type is described as sterile (2024 paper).
- Cultivation
- Not checked.
- Harvest and processing
- Dried rhizome powder, extract or tincture, and essential oil are the forms in the sources read; Ayurveda uses a purification step called Shodhana.
- Look-alikes and adulterants
- Name: Acorus gramineus (and A. tatarinowii, shi chang pu); Note: Related Acorus plants used in Chinese and Korean medicine. DNA tests were designed in 2014 to separate them from A. calamus because they can be confused in markets. GBIF lists A. tatarinowii as a synonym of A. calamus var. angustatus and A. gramineus as a separate species; this page does not cover them.; Name: Ayurvedic Vacha products; Note: Vacha is A. calamus; products may be single-herb or mixed formulas and were not reviewed here.
- Sustainability and conservation
- Not checked. A 2024 cryopreservation paper calls it an endangered medicinal plant in one setting (title only; not read).
Traditional use and history history, not clinical proof
| Tradition or era | Documented use | Source |
|---|---|---|
| Ayurveda, Unani, Siddha and Chinese medicine | Rhizome used for nervous disorders, appetite loss, bronchitis, colic, cramps, diarrhoea, indigestion, cough, fever, skin disease and debility (2014 review). | p24200497 |
| Vacha in Ayurveda | Used for neurological, gut, breathing, metabolic, kidney and liver disorders; traditionally for cognitive enhancement in infants. | p32325895 |
| European medicine (EMA list) | Stomach cramps, dysentery, asthma, worms, insecticide, tonic, stimulant. | s-ema-asarone-2005 |
| Flavouring use | Used as a flavouring, especially oil or extract, until US action in 1968 deemed added calamus in food adulterated. | s-cfr-189110 |
| Online sales as a 'hallucinogen' | Calamus products sold online as hallucinogenic led to poison-centre enquiries in Sweden in 2003-2006. | p20040135 |
Traditional use shows how a plant was used. It does not show that a supplement works or is safe today.
What is inside, and how it may work
What the plant contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.
Main compounds
| Compound | Family | Where it is concentrated | Activity studied | Level of evidence |
|---|---|---|---|---|
| Beta-asarone PubChem 5281758 | phenylpropene | Rhizome and leaf oils (type-dependent) Not detected in diploid; 9-19% of rhizome oil (triploid); 85-95% (tetraploid), per EMA | Genotoxic and carcinogenic in rodents; lab antidepressant-like, neuroprotective and other effects. 8 4 12 | Authoritative guidance |
| Alpha-asarone PubChem 636822 | phenylpropene | Rhizome | Carcinogenic in male mice (liver); activated by CYP3A4 to mutagenic epoxides in the lab. 5 12 3 | Laboratory research |
| Gamma-asarone PubChem 636750 | phenylpropene (allyl) | Not stated | Toxicology unknown except mutagenicity (2021 review). 21 12 | Review |
| Acorone and preisocalamendiol | sesquiterpenes | Rhizome extract (diploid type) Acorone 26.33% and preisocalamendiol 22.81% of a diploid extract | Marker compounds of the beta-asarone-free diploid type; no activity data read. PubChem ID not looked up. 2 | Lab chemistry |
Mechanisms, receptors and pathways
| Target or pathway | Gene or receptor | What was found | Level |
|---|---|---|---|
| NMDA receptor / glutamate excitotoxicity | NMDA receptor | Alpha- and beta-asarone protected cultured rat nerve cells from NMDA- or glutamate-induced damage by blocking NMDA receptor function (EMA). 8 | Laboratory research |
| Cytochrome P450 activation of asarones | CYP3A4, CYP2B6, CYP1A1 | CYP3A4 mainly forms alpha-asarone's mutagenic epoxides; beta-asarone is mainly epoxidised in human liver microsomes. 5 4 | Laboratory research |
| CYP3A4 and CYP2D6 inhibition | CYP3A4, CYP2D6 | A standardised extract blocked both enzymes in the test tube (moderate interaction potential). 14 | Laboratory research |
| Blood clotting | Not described | Anticoagulant effect of asarone in mice and rats (EMA). 8 | Animal research |
| Central nervous system depression | Not described | Sedative and body-temperature-lowering effects in rats (EMA); CNS-depressant effects listed in a 2014 review. 8 16 | Animal research |
Absorption, metabolism and elimination
- Absorption
- In rodents, oral bioavailability of alpha- and beta-asarone is poor (review); human absorption was not found.
- Distribution
- Not covered in the abstracts read.
- Metabolism
- Mainly cytochrome P450 pathways. Beta-asarone is mostly epoxidised at the side chain, then converted to diols and a ketone, in rat, cow, pig and human liver microsomes. Alpha-asarone epoxidation is mainly by CYP3A4. A trans-2,4,5-trimethoxycinnamic acid metabolite (PubChem CID 688363) and a hydroxylated metabolite were detected in people's urine after oil intoxication.
- Elimination
- Short plasma half-life in rodents (review). Urinary alpha-asarone about 11 to 1150 microgram/L and beta-asarone about 22 to 220 microgram/L in poisoned patients.
- Bioavailability
- Not established in people.
Isolated compounds versus whole extracts
Most pharmacology and all the cancer findings are for isolated asarones, while the traditional herb is the whole rhizome whose asarone content varies from none to very high. The one 2025 negative Ames test used an Indian rhizome, its extracts and pure beta-asarone, so whole-plant and isolated results can differ by type and test. No human trial compares them.
Nutritional composition
Calamus is not a nutrient or a food ingredient; it has no recognised nutritional role.
1 very low certainty11 not enough evidence
What is Calamus good for?
The uses people ask about and how strong the human evidence is for each. None is proven. All must be read with the safety section first: no source read shows a benefit that outweighs the cancer concern.
Benefits, one by one
Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.
Memory and thinking (traditional 'brain tonic' use)
Not enough evidenceCalamus (called Vacha in Ayurveda) has long been used as a brain and memory tonic, including for infants. No human trial shows it helps memory or thinking. The support is tradition plus lab and animal work, mostly on the asarone compounds that are also the main safety concern.
3 studiesNot specified for human use. Which variety was used matters: the EMA …
Studies, doses and limits
What the trials found
No human trial of calamus rhizome or its oil for this use was found in the sources read. The only human study found is an uncontrolled homeopathic-dilution study (see Body tab), which cannot speak to the herb.
Results
No human results. Animal and lab results are listed in the reviews without numbers in the abstracts.
Effect sizes as reported
None available.
Why this rating
Traditional use and lab/animal findings only; no human trials; the lab work is mostly on isolated asarones; abstracts only.
Form and dose studied
Not specified for human use. Which variety was used matters: the EMA statement shows beta-asarone ranges from none (diploid) to very high (tetraploid).
Who was studied
Not applicable (no human trials).
Limits
Abstract-level reading only. Lab and animal findings often do not carry over to people. The variety in one review (var. angustatus) is the type with the most beta-asarone.
Why researchers looked
A 2025 paper notes Vacha is traditionally used for cognitive enhancement in infants. A 2023 review says the tetraploid variety used in China has been used for amnesia and dementia for thousands of years and shows effects in Alzheimer's disease models in animals and cells.
Traditional use
Vacha is a traditional Indian herb for neurological complaints (2020 review). The Chinese plant sold as shi chang pu is a different herb and is not covered here.
Proposed mechanism Animal research
In lab and animal models the review lists effects against Alzheimer's-type changes and nerve-cell damage. Exact mechanisms were not in the abstracts read.
A proposed mechanism does not show that the effect happens in people.
Calamus (sweet flag) holds asarones that were genotoxic and caused liver cancer in rodents; the US treats added calamus in food as adulterated and EU/UK rules cap beta-asarone. See the Safety tab before any use. Giving it to infants has no safety data in the sources read; ask a paediatrician.
Mood and anxiety
Not enough evidenceReviews list antidepressant-like and anxiety-reducing effects of calamus extracts and asarone in animals. Nothing was found in people.
3 studiesNot specified for human use. Which variety was used matters: the EMA …
Studies, doses and limits
What the trials found
No human trial of calamus rhizome or its oil for this use was found in the sources read.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
Animal and lab findings only, summarised in reviews that say the claims still need testing.
Form and dose studied
Not specified for human use. Which variety was used matters: the EMA statement shows beta-asarone ranges from none (diploid) to very high (tetraploid).
Who was studied
Not applicable.
Limits
Reviews of preclinical work; abstracts only. The same reviews say further studies are needed to confirm the pharmacology.
Why researchers looked
Reviews of lab and animal work list antidepressant-like and anxiolytic-like effects of the plant and of alpha- and beta-asarone.
Traditional use
Used in Ayurveda and Chinese medicine for nervous disorders and depression (traditional-use review, 2014).
Proposed mechanism Animal research
Asarones act on several targets in animals; the reviews give no single mechanism.
A proposed mechanism does not show that the effect happens in people.
Calamus (sweet flag) holds asarones that were genotoxic and caused liver cancer in rodents; the US treats added calamus in food as adulterated and EU/UK rules cap beta-asarone. See the Safety tab before any use.
Calming and sleepiness (sedative effect)
Not enough evidenceThe European Medicines Agency lists sedative effects of asarone in rats, and a review lists central-nervous-system depressant effects of the rhizome. In people, the main reported effect after taking large amounts of calamus products was prolonged vomiting, not proven sleep benefit.
3 studiesNot specified for human use. Which variety was used matters: the EMA …
Studies, doses and limits
What the trials found
No sleep trial in people. The Swedish poisoning series (30 enquiries about intentional intoxication) reported prolonged vomiting as the main symptom; the abstract does not describe sedation or hallucinations.
Results
No human sleep results.
Effect sizes as reported
None available.
Why this rating
Animal evidence only; the human poisoning series describes harm, not benefit.
Form and dose studied
Not specified for human use. Which variety was used matters: the EMA statement shows beta-asarone ranges from none (diploid) to very high (tetraploid).
Who was studied
Not applicable.
Limits
A sedative effect in rats cannot be assumed in people. The poisoning series is not evidence of a benefit.
Why researchers looked
Sedation is one of the oldest listed effects in animals and may explain some of the traditional nerve-tonic use.
Traditional use
Used traditionally for nervous disorders (2014 review).
Proposed mechanism Animal research
Sedative and body-temperature-lowering effects in rats (EMA statement). Mechanism not described there.
A proposed mechanism does not show that the effect happens in people.
Calamus (sweet flag) holds asarones that were genotoxic and caused liver cancer in rodents; the US treats added calamus in food as adulterated and EU/UK rules cap beta-asarone. See the Safety tab before any use.
Seizures (anticonvulsant effect in animals)
Not enough evidenceCalamus extracts and asarone reduced seizures in animal models, according to reviews. There is no trial in people with epilepsy, and the herb should never replace seizure medicine.
3 studiesNot specified for human use. Which variety was used matters: the EMA …
Studies, doses and limits
What the trials found
No human trial of calamus rhizome or its oil for this use was found in the sources read.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
Animal findings only.
Form and dose studied
Not specified for human use. Which variety was used matters: the EMA statement shows beta-asarone ranges from none (diploid) to very high (tetraploid).
Who was studied
Not applicable.
Limits
Abstract-level reading only.
Why researchers looked
Anticonvulsant effects appear in the lists of pharmacological activity in three reviews.
Traditional use
Used in Chinese tradition for convulsion (2023 review).
Proposed mechanism Animal research
Not described in the abstracts read.
A proposed mechanism does not show that the effect happens in people.
Calamus (sweet flag) holds asarones that were genotoxic and caused liver cancer in rodents; the US treats added calamus in food as adulterated and EU/UK rules cap beta-asarone. See the Safety tab before any use. Anyone with epilepsy should not stop or change medicine because of this animal work.
Protecting nerve cells (lab finding)
Not enough evidenceIn cell and rat studies listed by the EMA, alpha- and beta-asarone protected nerve cells from damage caused by too much glutamate. This is a lab finding with no human evidence.
2 studiesNot specified for human use. Which variety was used matters: the EMA …
Studies, doses and limits
What the trials found
No human trial of calamus rhizome or its oil for this use was found in the sources read.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
Cell and animal findings only; the same compounds are classed as genotoxic in rodents.
Form and dose studied
Not specified for human use. Which variety was used matters: the EMA statement shows beta-asarone ranges from none (diploid) to very high (tetraploid).
Who was studied
Not applicable.
Limits
Statement from 2005 summarises older lab papers; those papers were not read.
Why researchers looked
The EMA statement lists protection against excitotoxicity (nerve damage from overactive glutamate signalling) among the lab findings for the asarones.
Traditional use
Not a traditional claim.
Proposed mechanism Laboratory research
Blockade of NMDA receptor function (cultured rat cortical neurons), per the EMA statement.
A proposed mechanism does not show that the effect happens in people.
Calamus (sweet flag) holds asarones that were genotoxic and caused liver cancer in rodents; the US treats added calamus in food as adulterated and EU/UK rules cap beta-asarone. See the Safety tab before any use.
Stomach cramps, indigestion and diarrhoea (traditional use)
Not enough evidenceCalamus rhizome is traditionally used for stomach cramps, colic, appetite loss, indigestion and dysentery. No trial in people was found, so there is no evidence of benefit, and the safety concerns are serious.
2 studiesNot specified for human use. Which variety was used matters: the EMA …
Studies, doses and limits
What the trials found
No human trial of calamus rhizome or its oil for this use was found in the sources read.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
Traditional use and lab/animal claims only.
Form and dose studied
Not specified for human use. Which variety was used matters: the EMA statement shows beta-asarone ranges from none (diploid) to very high (tetraploid).
Who was studied
Not applicable.
Limits
Abstract-level reading only.
Why researchers looked
These are the oldest and most widely listed uses, named by the EMA and in reviews.
Traditional use
Listed in Ayurveda, Unani, Siddha and Chinese tradition: stomach cramps, dysentery, colic, flatulence, indigestion, diarrhoea (EMA 2005; 2014 review).
Proposed mechanism Traditional use
Antispasmodic and antidiarrhoeal effects are listed from animal and lab work; no mechanism given in the abstract.
A proposed mechanism does not show that the effect happens in people.
Calamus (sweet flag) holds asarones that were genotoxic and caused liver cancer in rodents; the US treats added calamus in food as adulterated and EU/UK rules cap beta-asarone. See the Safety tab before any use.
Cough, bronchitis and asthma (traditional use)
Not enough evidenceTraditional use for asthma, bronchitis and cough. No human evidence was found.
2 studiesNot specified for human use. Which variety was used matters: the EMA …
Studies, doses and limits
What the trials found
No human trial of calamus rhizome or its oil for this use was found in the sources read.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
Traditional use only.
Form and dose studied
Not specified for human use. Which variety was used matters: the EMA statement shows beta-asarone ranges from none (diploid) to very high (tetraploid).
Who was studied
Not applicable.
Limits
Abstract-level reading only.
Why researchers looked
Named in the EMA list of traditional uses and in the 2014 review.
Traditional use
Asthma (EMA); bronchitis, cough, chest pain (2014 review).
Proposed mechanism Traditional use
Not described in the abstracts read.
A proposed mechanism does not show that the effect happens in people.
Calamus (sweet flag) holds asarones that were genotoxic and caused liver cancer in rodents; the US treats added calamus in food as adulterated and EU/UK rules cap beta-asarone. See the Safety tab before any use.
Blood sugar, blood fats and blood pressure (lab findings)
Not enough evidenceReviews list antidiabetic, cholesterol-lowering, blood-pressure-lowering and anti-obesity effects in lab and animal studies. No human trial was found.
3 studiesNot specified for human use. Which variety was used matters: the EMA …
Studies, doses and limits
What the trials found
No human trial of calamus rhizome or its oil for this use was found in the sources read.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
Animal and lab findings only; no human blood tests were found.
Form and dose studied
Not specified for human use. Which variety was used matters: the EMA statement shows beta-asarone ranges from none (diploid) to very high (tetraploid).
Who was studied
Not applicable.
Limits
Abstract-level reading only; no numbers given.
Why researchers looked
Metabolic effects appear in the activity lists of three reviews, mostly from animal models.
Traditional use
Used in Ayurveda for metabolic complaints (2020 review).
Proposed mechanism Animal research
Not described in the abstracts read.
A proposed mechanism does not show that the effect happens in people.
Calamus (sweet flag) holds asarones that were genotoxic and caused liver cancer in rodents; the US treats added calamus in food as adulterated and EU/UK rules cap beta-asarone. See the Safety tab before any use. People on diabetes or blood-pressure medicine should not use it as a substitute.
Inflammation and immune activity (lab findings)
Not enough evidenceAnti-inflammatory, antioxidant and immune-modulating effects are listed in reviews of lab and animal work. No human evidence was found.
2 studiesNot specified for human use. Which variety was used matters: the EMA …
Studies, doses and limits
What the trials found
No human trial of calamus rhizome or its oil for this use was found in the sources read.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
Animal and lab findings only.
Form and dose studied
Not specified for human use. Which variety was used matters: the EMA statement shows beta-asarone ranges from none (diploid) to very high (tetraploid).
Who was studied
Not applicable.
Limits
Abstract-level reading only.
Why researchers looked
Listed among the pharmacological activities in reviews.
Traditional use
Used traditionally for rheumatism and inflammation (2014 review).
Proposed mechanism Animal research
Not described in the abstracts read.
A proposed mechanism does not show that the effect happens in people.
Calamus (sweet flag) holds asarones that were genotoxic and caused liver cancer in rodents; the US treats added calamus in food as adulterated and EU/UK rules cap beta-asarone. See the Safety tab before any use.
Worms, germs and insects (lab findings)
Not enough evidenceThe EMA statement lists worm-killing and insect-killing activity of asarone in the lab, and reviews list antimicrobial effects. This is not evidence that it treats infections or worms in people.
2 studiesNot specified for human use. Which variety was used matters: the EMA …
Studies, doses and limits
What the trials found
No human trial of calamus rhizome or its oil for this use was found in the sources read.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
Lab tests only.
Form and dose studied
Not specified for human use. Which variety was used matters: the EMA statement shows beta-asarone ranges from none (diploid) to very high (tetraploid).
Who was studied
Not applicable.
Limits
Toxicity to worms and insects is also a reminder that the compounds are biologically active.
Why researchers looked
Traditional use against worms (anthelmintic) and as an insecticide.
Traditional use
Worm treatment and insecticide use (EMA 2005).
Proposed mechanism Laboratory research
Nematocidal and mosquito-larvae-killing activity of asarone in lab assays (EMA).
A proposed mechanism does not show that the effect happens in people.
Calamus (sweet flag) holds asarones that were genotoxic and caused liver cancer in rodents; the US treats added calamus in food as adulterated and EU/UK rules cap beta-asarone. See the Safety tab before any use.
Anti-cancer effects in cells (lab finding that conflicts with the safety record)
Not enough evidenceSome lab studies report anticancer effects of beta-asarone, yet the same compound is classed by regulators as genotoxic and a liver carcinogen in rodents. This is not a reason to use calamus against cancer.
3 studiesNot specified for human use. Which variety was used matters: the EMA …
Studies, doses and limits
What the trials found
No human trial of calamus rhizome or its oil for this use was found in the sources read.
Results
No human results.
Effect sizes as reported
None available.
Why this rating
Cell/animal findings only, in direct tension with the carcinogenicity findings.
Form and dose studied
Not specified for human use. Which variety was used matters: the EMA statement shows beta-asarone ranges from none (diploid) to very high (tetraploid).
Who was studied
Not applicable.
Limits
The same compounds are reported to cause liver tumours in rodents.
Why researchers looked
A review says anticancer effects of beta-asarone 'should be further studied' in animals.
Traditional use
Tumours are in the traditional use list (2014 review).
Proposed mechanism Laboratory research
Not described in the abstracts read.
A proposed mechanism does not show that the effect happens in people.
Calamus (sweet flag) holds asarones that were genotoxic and caused liver cancer in rodents; the US treats added calamus in food as adulterated and EU/UK rules cap beta-asarone. See the Safety tab before any use.
A homeopathic Acorus calamus medicine (open-label study)
Very low certaintyOne uncontrolled study of 321 people in India reported symptom improvement with a homeopathic Acorus calamus medicine across many complaints. It had no control group and a homeopathic dilution is not the herb, so it says nothing about the rhizome.
1 studiesHomeopathic medicine (dilution); not the herb.
Studies, doses and limits
What the trials found
321 completers at 14 sites; the authors report significant improvement on MYMOP-2 and ORIDL (p < 0.0001) in headache, constipation, rhinitis, cough, muscle and joint pain and eczema.
Results
Self-rated scores improved (p < 0.0001) in a single group.
Effect sizes as reported
No effect size in the abstract.
Why this rating
Uncontrolled, open-label, mixed conditions, self-rated outcomes, homeopathic preparation.
Form and dose studied
Homeopathic medicine (dilution); not the herb.
Who was studied
People with at least three matching symptoms.
Limits
No control group or blinding; cannot separate the medicine from natural recovery or expectation.
Why researchers looked
Run to 'verify' the medicine's use in homeopathy (CCRH Clinical Verification Program).
Traditional use
Homeopathy, not a traditional herbal use.
Proposed mechanism Other
Not applicable.
A proposed mechanism does not show that the effect happens in people.
Homeopathic dilutions contain little or no plant material, so this does not apply to the raw rhizome or oil.
Connections to the rest of health
How Calamus connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.
Explore every connection: goals, body systems, organs, symptoms, genes
A. Wellness goals
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Memory Support | Traditional use | Not enough evidence | Memory and thinking (traditional 'brain tonic' use): Calamus (called Vacha in Ayurveda) has long been used as a brain and memory tonic, including for infants. No human trial shows it helps memory or thinking. The support is tradition plus lab and animal work, mostly on the asarone compounds that are also the main safety concern. | 10 18 13 |
| Brain Health | Traditional use | Not enough evidence | Memory and thinking (traditional 'brain tonic' use): Calamus (called Vacha in Ayurveda) has long been used as a brain and memory tonic, including for infants. No human trial shows it helps memory or thinking. The support is tradition plus lab and animal work, mostly on the asarone compounds that are also the main safety concern. | 10 18 13 |
| Mental Clarity | Traditional use | Not enough evidence | Memory and thinking (traditional 'brain tonic' use): Calamus (called Vacha in Ayurveda) has long been used as a brain and memory tonic, including for infants. No human trial shows it helps memory or thinking. The support is tradition plus lab and animal work, mostly on the asarone compounds that are also the main safety concern. | 10 18 13 |
| Anxiety Support | Not enough evidence | Mood and anxiety: Reviews list antidepressant-like and anxiety-reducing effects of calamus extracts and asarone in animals. Nothing was found in people. | 6 10 16 | |
| Mood Balance | Not enough evidence | Mood and anxiety: Reviews list antidepressant-like and anxiety-reducing effects of calamus extracts and asarone in animals. Nothing was found in people. | 6 10 16 | |
| Calm Relaxation | Not enough evidence | Mood and anxiety: Reviews list antidepressant-like and anxiety-reducing effects of calamus extracts and asarone in animals. Nothing was found in people. Calming and sleepiness (sedative effect): The European Medicines Agency lists sedative effects of asarone in rats, and a review lists central-nervous-system depressant effects of the rhizome. In people, the main reported effect after taking large amounts of calamus products was prolonged vomiting, not proven sleep benefit. | 6 10 16 8 3 | |
| Better Sleep | Not enough evidence | Calming and sleepiness (sedative effect): The European Medicines Agency lists sedative effects of asarone in rats, and a review lists central-nervous-system depressant effects of the rhizome. In people, the main reported effect after taking large amounts of calamus products was prolonged vomiting, not proven sleep benefit. | 8 16 3 | |
| Brain Health | Not enough evidence | Seizures (anticonvulsant effect in animals): Calamus extracts and asarone reduced seizures in animal models, according to reviews. There is no trial in people with epilepsy, and the herb should never replace seizure medicine. | 10 6 16 | |
| Brain Health | Not enough evidence | Protecting nerve cells (lab finding): In cell and rat studies listed by the EMA, alpha- and beta-asarone protected nerve cells from damage caused by too much glutamate. This is a lab finding with no human evidence. | 8 6 | |
| Cellular Protection | Not enough evidence | Protecting nerve cells (lab finding): In cell and rat studies listed by the EMA, alpha- and beta-asarone protected nerve cells from damage caused by too much glutamate. This is a lab finding with no human evidence. | 8 6 | |
| Digestive Support | Traditional use | Not enough evidence | Stomach cramps, indigestion and diarrhoea (traditional use): Calamus rhizome is traditionally used for stomach cramps, colic, appetite loss, indigestion and dysentery. No trial in people was found, so there is no evidence of benefit, and the safety concerns are serious. | 8 16 |
| Gut Health | Traditional use | Not enough evidence | Stomach cramps, indigestion and diarrhoea (traditional use): Calamus rhizome is traditionally used for stomach cramps, colic, appetite loss, indigestion and dysentery. No trial in people was found, so there is no evidence of benefit, and the safety concerns are serious. | 8 16 |
| Breathing Support | Traditional use | Not enough evidence | Cough, bronchitis and asthma (traditional use): Traditional use for asthma, bronchitis and cough. No human evidence was found. | 8 16 |
| Lung Support | Traditional use | Not enough evidence | Cough, bronchitis and asthma (traditional use): Traditional use for asthma, bronchitis and cough. No human evidence was found. | 8 16 |
| Blood Sugar Balance | Not enough evidence | Blood sugar, blood fats and blood pressure (lab findings): Reviews list antidiabetic, cholesterol-lowering, blood-pressure-lowering and anti-obesity effects in lab and animal studies. No human trial was found. | 18 16 6 | |
| Cholesterol Balance | Not enough evidence | Blood sugar, blood fats and blood pressure (lab findings): Reviews list antidiabetic, cholesterol-lowering, blood-pressure-lowering and anti-obesity effects in lab and animal studies. No human trial was found. | 18 16 6 | |
| Blood Pressure Support | Not enough evidence | Blood sugar, blood fats and blood pressure (lab findings): Reviews list antidiabetic, cholesterol-lowering, blood-pressure-lowering and anti-obesity effects in lab and animal studies. No human trial was found. | 18 16 6 | |
| Weight Management | Not enough evidence | Blood sugar, blood fats and blood pressure (lab findings): Reviews list antidiabetic, cholesterol-lowering, blood-pressure-lowering and anti-obesity effects in lab and animal studies. No human trial was found. | 18 16 6 | |
| Inflammation Balance | Not enough evidence | Inflammation and immune activity (lab findings): Anti-inflammatory, antioxidant and immune-modulating effects are listed in reviews of lab and animal work. No human evidence was found. | 18 16 | |
| Immune Support | Not enough evidence | Inflammation and immune activity (lab findings): Anti-inflammatory, antioxidant and immune-modulating effects are listed in reviews of lab and animal work. No human evidence was found. Worms, germs and insects (lab findings): The EMA statement lists worm-killing and insect-killing activity of asarone in the lab, and reviews list antimicrobial effects. This is not evidence that it treats infections or worms in people. | 18 16 8 | |
| Cellular Protection | Not enough evidence | Anti-cancer effects in cells (lab finding that conflicts with the safety record): Some lab studies report anticancer effects of beta-asarone, yet the same compound is classed by regulators as genotoxic and a liver carcinogen in rodents. This is not a reason to use calamus against cancer. | 6 21 8 | |
| Holistic Balance | Very low certainty | A homeopathic Acorus calamus medicine (open-label study): One uncontrolled study of 321 people in India reported symptom improvement with a homeopathic Acorus calamus medicine across many complaints. It had no control group and a homeopathic dilution is not the herb, so it says nothing about the rhizome. | 1 |
B. Body systems
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Nervous System | Biological association | Not enough evidence | Studied for: Memory and thinking (traditional 'brain tonic' use) Studied for: Mood and anxiety | 10 18 13 6 16 8 3 |
| Digestive System | Biological association | Not enough evidence | Studied for: Stomach cramps, indigestion and diarrhoea (traditional use) Studied for: Worms, germs and insects (lab findings) | 8 16 |
| Respiratory System | Biological association | Not enough evidence | Studied for: Cough, bronchitis and asthma (traditional use) | 8 16 |
| Endocrine System | Biological association | Not enough evidence | Studied for: Blood sugar, blood fats and blood pressure (lab findings) | 18 16 6 |
| Cardiovascular System | Biological association | Not enough evidence | Studied for: Blood sugar, blood fats and blood pressure (lab findings) | 18 16 6 |
| Immune System | Biological association | Not enough evidence | Studied for: Inflammation and immune activity (lab findings) Studied for: Worms, germs and insects (lab findings) | 18 16 8 6 21 1 |
C. Body parts and organs
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Liver | Adverse effect or risk | Low certainty | Liver cancer in rodents; no human data. Preparation or compound: Alpha- and beta-asarone from calamus |
8 10 |
| Skin | Adverse effect or risk | Low certainty | Irritant and moderate sensitiser in lab models. Preparation or compound: Rhizome essential oil |
7 |
J. Genes, receptors and enzymes
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| CYP3A4 | Preliminary mechanism | In vitro | Main enzyme making alpha-asarone's mutagenic epoxides; also inhibited by calamus extract in the test tube. | 5 14 |
| CYP2D6 | Preliminary mechanism | In vitro | Inhibited by calamus extract in the test tube. | 14 |
| NMDA receptor | Preliminary mechanism | In vitro | Blocked by asarones in rat nerve cells. | 8 |
L. Active compounds
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Beta-asarone | Biological association | Authoritative guidance | Genotoxic and carcinogenic in rodents; lab antidepressant-like, neuroprotective and other effects. Preparation or compound: Rhizome and leaf oils (type-dependent) |
8 4 12 |
| Alpha-asarone | Biological association | In vitro | Carcinogenic in male mice (liver); activated by CYP3A4 to mutagenic epoxides in the lab. Preparation or compound: Rhizome |
5 12 3 |
| Gamma-asarone | Biological association | Review | Toxicology unknown except mutagenicity (2021 review). Preparation or compound: Not stated |
21 12 |
| Acorone and preisocalamendiol | Biological association | Lab chemistry | Marker compounds of the beta-asarone-free diploid type; no activity data read. PubChem ID not looked up. Preparation or compound: Rhizome extract (diploid type) |
2 |
Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 25, 2026).
The evidence
The research centre for Calamus. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.
Evidence by outcome
Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).
How we rate evidence
High certainty
Several well-run trials or reviews agree; further research is unlikely to change the picture much.
Moderate certainty
Good trials point the same way, but some doubt remains.
Low certainty
Small, short or inconsistent trials. The finding could change with better research.
Very low certainty
Very little or very weak human data. Treat as a possibility only.
Mixed findings
Trials or reviews disagree with each other.
Not enough evidence
Not enough human research to say either way.
Evidence against
Good research found no benefit, or found harm.
We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We searched PubMed and read abstracts of 17 PubMed papers; read the full EMA asarone statement, the US rule 21 CFR 189.110 and the UK-published EU flavourings annex; checked the plant name in GBIF and NCBI Taxonomy and compound IDs in PubChem. NCCIH, Health Canada, LiverTox, LactMed and an HMPC monograph were not found.
Study library: every study we checked 21
| Study | Design | People | Product, dose, length | Result |
|---|---|---|---|---|
| Azis 2026 Exploring the Homeopathic Therapeutic Potential of Acorus calamus: A Multi-center Open-Label Clinical Verification Study. Homeopathy · PMID 40921187 · DOI |
Open label trial |
321 321 people who completed at least two follow-ups at 14 homeopathy hospitals or clinics in India, with at least three symptoms matching the remedy's 'proving' symptoms |
Homeopathic Acorus calamus medicine (homeopathic dilution, NOT the herb) not specified n/a n/a · vs n/a |
The authors report significant improvement in MYMOP-2 and ORIDL scores (p < 0.0001) across a mix of complaints (headache, constipation, rhinitis, cough, muscle and joint pain, eczema). They call for randomised trials. Improvement in an uncontrolled single-group study; cannot show the medicine caused it Methods, limits and fundingOutcomes: Change in MYMOP-2 symptom score; ORIDL daily-living scale Limitations: No control group, no blinding, mixed conditions, self-rated outcomes, so natural recovery and expectation cannot be ruled out. Homeopathic dilutions are not comparable with the herb or its oil. Dose and duration not in the abstract. Funding and conflicts: Run by the Central Council for Research in Homoeopathy, a homeopathy research body (per the abstract); no other funding detail in the abstract. Read: abstract |
| Bertea 2005 Identification of an EcoRI restriction site for a rapid and precise determination of beta-asarone-free Acorus calamus cytotypes. Phytochemistry · PMID 15721942 · DOI |
Lab analysis plant chemistry |
Diploid and triploid A. calamus alcoholic extracts | Alcoholic extracts of diploid and triploid rhizome rhizome n/a n/a · vs n/a |
Triploid extracts had β-asarone as the main compound (11%). The diploid extracts completely lacked β-asarone and were rich in other compounds such as acorone (26.33%) and preisocalamendiol (22.81%). A DNA test (EcoRI cut pattern of a 5S-rRNA spacer) separated the diploid type from the others. Diploid type had no β-asarone; triploid had 11% in the extract Methods, limits and fundingOutcomes: Chemical profile (GC-MS) and DNA test to tell the types apart Limitations: Small sample of plants; abstract only read. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Björnstad 2009 Bioanalytical investigation of asarone in connection with Acorus calamus oil intoxications. Journal of Analytical Toxicology · PMID 20040135 · DOI |
Case series |
7 People with intentional calamus-oil intoxication reported to the Swedish Poisons Information Centre in 2003-2006 (30 enquiries; urine analysed in 7 cases) |
Calamus products sold online as 'hallucinogenic' oil / plant preparations (not specified in the abstract) n/a n/a · vs n/a |
α-Asarone was found in 5 of 7 urine samples (about 11 to 1150 microgram/L) and β-asarone in 4 of those (about 22 to 220 microgram/L). No evidence was found for 2,4,5-trimethoxyamphetamine, a compound claimed to be the hallucinogenic part. The main symptom reported by patients was prolonged vomiting, sometimes lasting more than 15 hours. Asarone was detectable in urine after intentional use; vomiting was the main symptom Methods, limits and fundingOutcomes: Presence of α- and β-asarone and metabolites in urine; clinical symptoms Limitations: Small number of urine samples; amounts taken are not in the abstract; the abstract does not say whether any hallucinations were seen. Funding and conflicts: Research Support, Non-U.S. Gov't (as indexed); no further detail in the abstract. Read: abstract |
| Cartus 2015 Hepatic metabolism of carcinogenic β-asarone. Chemical Research in Toxicology · PMID 26273788 · DOI |
Laboratory research liver microsomes (rat, cow, pig, human) |
Liver microsomes from rats, cattle, pigs and humans | β-asarone n/a (compound) n/a n/a · vs n/a |
Describes β-asarone as genotoxic and carcinogenic in rodents (liver and small intestine). In liver microsomes of all four species the main route was epoxidation of the side chain (followed by conversion to diols and a ketone). Species differences were small. The authors say the way β-asarone causes cancer is still unknown. Same main metabolic route in human liver microsomes as in animals Methods, limits and fundingOutcomes: Metabolites of β-asarone Limitations: Lab enzyme study. Abstract read here was cut off before the final sentence, so no further figures are cited. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Cartus 2020 Metabolism of carcinogenic alpha-asarone by human cytochrome P450 enzymes. Naunyn-Schmiedeberg's Archives of Pharmacology · PMID 31485694 · DOI |
Laboratory research human enzymes (lab) |
Eight human cytochrome P450 enzymes (Supersomes) | α-asarone n/a (compound) n/a n/a · vs n/a |
The reactive side-chain epoxides (mutagenic, DNA-binding, thought to cause liver cancer in male mice) were made mainly by CYP3A4, and to a lesser extent CYP2B6 and CYP1A1. The authors conclude the capacity to activate α-asarone is widespread in the general population. CYP3A4 is the main activating enzyme for α-asarone in the lab Methods, limits and fundingOutcomes: Which human enzymes make α-asarone's reactive epoxides Limitations: Lab study; does not show harm in people. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Chellian 2017 Pharmacology and toxicology of α- and β-Asarone: A review of preclinical evidence. Phytomedicine · PMID 28732807 · DOI |
Narrative review lab + animal (as reviewed) |
Preclinical (lab and animal) literature on α- and β-asarone, 1960 to January 2017 | α- and β-asarone n/a (compounds) n/a n/a · vs n/a |
In rodents oral bioavailability of both asarones is poor with a short half-life, and metabolism is mainly through cytochrome P450 pathways. Preclinical activities reported include antidepressant, anti-anxiety, anti-Alzheimer's, anti-Parkinson's, antiepileptic, anticancer, lipid-lowering, antithrombotic and others. Toxicology studies showed both can cause liver tumours (hepatomas) and might be mutagenic, genotoxic and teratogenic. Preclinical benefits and toxicity side by side; no human data Methods, limits and fundingOutcomes: Pharmacokinetics, pharmacology, toxicity Limitations: Abstract only read; the authors say further dose-dependent in vivo work is needed to confirm toxicity. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Desai 2025 Comprehensive In Vitro Safety Assessment of Acorus calamus Rhizome Oil Using OECD-Compliant New Approach Methods: Classification as a GHS Category 1B Sensitiser and Category 2 Irritant. Toxics · PMID 41441227 · DOI |
Laboratory research lab (reconstructed skin, cell assays) |
Lab skin models and cell tests of one rhizome oil | A. calamus rhizome essential oil (β-asarone about 40.75%) rhizome oil n/a n/a · vs n/a |
The oil was predicted to be a Category 2 skin irritant, not corrosive, and a GHS Category 1B skin sensitiser (moderate). Irritation in reconstructed human skin models was reversible. Modelled 'safe-use' concentrations were 0.13 to 0.78% (w/w) in leave-on products and up to 7.46% in rinse-off products. Moderate sensitiser and irritant in lab models Methods, limits and fundingOutcomes: Skin irritation, corrosion and sensitisation Limitations: Lab models, not tested on people. One oil sample. Funding and conflicts not stated in the abstract. Funding and conflicts: Not stated in the abstract. Read: abstract |
| European Medicines Agency 2005 EMEA (HMPC working party): Public statement on the use of herbal medicinal products containing asarone (2005) European Medicines Agency · Source |
Authoritative guidance n/a |
n/a | Asarones; Acorus calamus and other plants rhizome and leaf n/a n/a · vs n/a |
Full 7-page statement read. Alpha- and beta-asarone are 'genotoxic and hepatocarcinogens in rodents'. Asarone content depends on the type: diploid var. americanus none detected in leaf or rhizome oil; triploid var. calamus rhizome oil 9-19% (dried rhizome 0.3%) and leaf oil 50-65%; tetraploid var. angustatus rhizome oil 85-95% (dried rhizome 4.4-8.3%). Traditional uses listed: stomach cramps, dysentery, asthma, worms, insecticide, tonic, stimulant. Animal/lab findings listed: reduced mobility, worm-killing, anticoagulant effect in mouse and rat, sedative and hypothermic effects in rats, protection of rat nerve cells from NMDA/glutamate excitotoxicity. Conclusion: asarone in herbal medicines should be reduced to a minimum and diploid varieties always preferred; by analogy with food rules a temporary exposure limit of about 115 microgram a day (about 2 microgram per kg body weight a day) could be accepted until a full benefit/risk assessment is done. Regulator advice: keep asarone to a minimum; prefer diploid types Methods, limits and fundingOutcomes: Toxicity, content by type, medicinal uses, pharmacology, conclusion Limitations: From 2005; no newer HMPC statement or monograph was found. The 115 microgram figure is a temporary exposure limit for asarone, not a recommended amount of any product. Funding and conflicts: Regulator document. Read: full-text |
| GBIF 2026 GBIF Backbone Taxonomy: Acorus calamus L. (species match, synonyms and related names, retrieved 2026-10-25) GBIF · Source |
Database record n/a |
n/a | n/a n/a n/a n/a · vs n/a |
GBIF key 2873769: Acorus calamus L., ACCEPTED, family Acoraceae, order Acorales. Listed synonyms include Acorus aromaticus Gueldenst., Acorus vulgaris Simonk., Calamus aromaticus Garsault and Calamus aromaticus Ledeb. Acorus tatarinowii Schott (key 2873797) is listed as a SYNONYM that points to Acorus calamus var. angustatus Besser (key 2873796, ACCEPTED variety). Acorus gramineus Aiton is a separate ACCEPTED species. Accepted species and name relations Methods, limits and fundingOutcomes: Accepted name, synonyms, related species Limitations: GBIF grouping differs from Chinese-medicine usage, where shi chang pu (A. tatarinowii) is treated as its own herb. Funding and conflicts: n/a Read: full-text |
| He 2023 Acorus calamus var. angustatus Besser: Insight into current research on ethnopharmacological use, phytochemistry, pharmacology, toxicology, and pharmacokinetics. Phytochemistry · PMID 36871902 · DOI |
Systematic review lab + animal (as reviewed) |
Literature on one variety (A. calamus var. angustatus, used in China and other Asian countries), searched to December 2022 | Rhizome and its compounds (asarone analogues, lignans) rhizome n/a n/a · vs n/a |
Says the variety has been used for coma, convulsion, amnesia and dementia for thousands of years. 234 small molecules identified. Lab and animal studies show effects in Alzheimer's models, anticonvulsant, antidepressant-like, anxiolytic-like, anti-fatigue, anti-Parkinson and neuroprotective models. States that the 'clinical therapeutic dose' shows no toxic effect, but excess α- and β-asarone may cause toxicity, and their epoxide metabolites may be toxic to the liver. Lab and animal signals only; no human trial summarised in the abstract Methods, limits and fundingOutcomes: Traditional use, chemistry, pharmacology, toxicology, pharmacokinetics Limitations: Review of lab and animal work, not a pooled analysis of trials. This is the tetraploid variety, which can hold far more β-asarone than other types (see the EMA statement). The 'no toxic effect at clinical dose' wording is the authors' own and is not backed by numbers in the abstract. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Maurya 2015 Śodhana: An Ayurvedic process for detoxification and modification of therapeutic activities of poisonous medicinal plants. Ancient Science of Life · PMID 26283803 · DOI |
Narrative review n/a (review) |
Review of Ayurvedic purification (Śodhana) of toxic medicinal plants | Ayurvedic purification of toxic plants including Acorus calamus n/a n/a n/a · vs n/a |
Lists Acorus calamus among toxic plants still used in Indian medicine, names β-asarone as its toxic component, and says Śodhana is intended to reduce toxic principles. The abstract gives no data on how much β-asarone is removed. Tradition says purification lowers toxicity; amount not shown in the abstract Methods, limits and fundingOutcomes: Role of purification in lowering toxic principles Limitations: Abstract only. No measured β-asarone reduction in the abstract. Funding and conflicts: Not stated in the abstract. Read: abstract |
| NCBI PubChem 2026 PubChem compound records: alpha-asarone (CID 636822), beta-asarone (CID 5281758), gamma-asarone (CID 636750), 2,4,5-trimethoxycinnamic acid (CID 688363); retrieved 2026-10-25 PubChem · Source |
Database record n/a |
n/a | n/a n/a n/a n/a · vs n/a |
CID 636822 = 1,2,4-trimethoxy-5-[(E)-prop-1-enyl]benzene (alpha-asarone), C12H16O3. CID 5281758 = the (Z) isomer (beta-asarone), C12H16O3. CID 636750 = 1,2,4-trimethoxy-5-prop-2-enylbenzene (gamma-asarone), C12H16O3. CID 688363 = (E)-3-(2,4,5-trimethoxyphenyl)prop-2-enoic acid, C12H14O5. Compound identity confirmed Methods, limits and fundingOutcomes: Compound identity Limitations: Identity only. Funding and conflicts: n/a Read: full-text |
| Narayana 2025 Reporting negative Ames test results for Indian Acorus calamus L., rhizome, extracts, and beta asarone. Indian Journal of Pharmacology · PMID 40844059 · DOI |
Laboratory research bacteria (lab) |
Bacterial mutation test (Ames, OECD guideline, GLP) with five Salmonella strains, with and without rat liver enzymes | Indian A. calamus rhizome powder, acidic and alkaline water extracts, and pure β-asarone rhizome n/a n/a · vs n/a |
No mutagenic response was seen with any sample in any of the five strains, with or without metabolic activation (doses 39.06 to 5000 microgram per plate). Positive controls worked as expected. The authors note β-asarone has shown potential genotoxicity in some other in vitro studies, and recommend chronic toxicity and carcinogenicity tests. Negative in this one bacterial mutation test Methods, limits and fundingOutcomes: Mutagenic response (revertant colony counts) Limitations: One lab test, one bacterial system. A negative Ames test does not rule out carcinogenicity in animals or people (the authors themselves ask for longer-term studies). Funding not stated in the abstract. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Pandit 2011 Metabolism mediated interaction of α-asarone and Acorus calamus with CYP3A4 and CYP2D6. Fitoterapia · PMID 21062640 · DOI |
Laboratory research enzyme assay (lab) |
Test-tube enzyme assays with a standardised calamus rhizome extract and α-asarone | Standardised A. calamus rhizome extract; α-asarone rhizome n/a n/a · vs n/a |
A carbon-monoxide binding test showed moderate interaction potential. The extract blocked CYP3A4 and CYP2D6 in the test tube (IC50 about 33 to 47 microgram/ml) and was more potent than α-asarone alone (about 42 to 65 microgram/ml). Moderate enzyme-interaction potential in the test tube Methods, limits and fundingOutcomes: Interaction with CYP450, CYP3A4 and CYP2D6 enzymes Limitations: Test-tube only; no animal or human interaction data. IC50 values are lab concentrations, not body doses. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Prinsloo 2025 Environmental and internal drivers of genotoxic carcinogens accumulation in botanicals and their preparations. Archives of Toxicology · PMID 40646165 · DOI |
Narrative review n/a (review) |
Review of how growing conditions and plant genetics change the levels of genotoxic or carcinogenic compounds in plants | General botanicals (calamus content not confirmed from the abstract) n/a n/a n/a · vs n/a |
Says levels of genotoxic or carcinogenic compounds in plants vary greatly with chemotype, cultivar, water stress, soil, location and development, that the effects are unpredictable, and that exposure should be compared with human safety thresholds. General message: contents vary Methods, limits and fundingOutcomes: Variation of hazardous compound levels Limitations: Only the abstract was read, and it does not name calamus. A previous summary of this paper listed it for asarone accumulation; the calamus-specific content is summary-only and NOT re-verified here. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Rajput 2014 An overview on traditional uses and pharmacological profile of Acorus calamus Linn. (Sweet flag) and other Acorus species. Phytomedicine · PMID 24200497 · DOI |
Narrative review lab + animal (as reviewed) |
Literature on traditional uses and lab pharmacology of A. calamus and other Acorus species | Rhizome, leaves and essential oil rhizome (mainly) n/a n/a · vs n/a |
Lists traditional uses in Ayurveda, Unani, Siddha and Chinese medicine (nervous disorders, appetite loss, bronchitis, colic, cramps, diarrhoea, indigestion, cough, fever, skin disease and more). Names α- and β-asarone as the main active parts. Reported lab activities include sedative, CNS-depressant, anticonvulsant, antispasmodic, cardiovascular, lipid-lowering, immune-suppressing, anti-inflammatory, antioxidant, antimicrobial, anticancer and antidiabetic effects. States that genotoxicity and mutagenicity of α- and β-asarone limit use 'at high dosage' and that many uses 'are yet to be scientifically validated'. Traditional use plus lab findings; not validated in humans Methods, limits and fundingOutcomes: Traditional uses; lab activities; genotoxicity Limitations: Abstract only read; no numbers; mixes several Acorus species. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Ryuk 2014 Identification of Acorus gramineus, A. calamus, and A. tatarinowii using sequence characterized amplified regions (SCAR) primers for monitoring of Acori graminei rhizoma in Korean markets. International Journal of Clinical and Experimental Medicine · PMID 25356101 |
Lab analysis plant DNA |
Acorus gramineus, A. calamus and A. tatarinowii plant material and a commercial Acori Graminei Rhizoma sample set | Rhizome (DNA identification) rhizome n/a n/a · vs n/a |
Designed DNA primers that can separate A. gramineus, A. calamus and A. tatarinowii by multiplex PCR, so market rhizome sold as A. gramineus can be checked. The abstract does not report how many market samples were wrongly identified. Species can be confused and can be told apart by DNA tests Methods, limits and fundingOutcomes: DNA markers to tell three Acorus species apart Limitations: Abstract only; no market-mix-up rate given. No DOI found in the PubMed record. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Sharma 2020 Role of Vacha (Acorus calamus Linn.) in Neurological and Metabolic Disorders: Evidence from Ethnopharmacology, Phytochemistry, Pharmacology and Clinical Study. Journal of Clinical Medicine · PMID 32325895 · DOI |
Narrative review lab + animal (as reviewed) |
Literature on Vacha (Acorus calamus) in neurological and metabolic disorders | Rhizome extracts and compounds rhizome n/a n/a · vs n/a |
Describes Vacha as a traditional Indian herb used for neurological, gut, breathing, metabolic, kidney and liver complaints. 145 constituents identified. Says evidence is 'suggestive of the biopotential' of extracts and compounds in metabolic and neurological disorders (anticonvulsant, antidepressant, antihypertensive, anti-inflammatory, immune-modulating, neuroprotective, cardioprotective, anti-obesity effects). The abstract gives no human trial results. Mostly lab and animal findings; no human effect size in the abstract Methods, limits and fundingOutcomes: Ethnomedicinal use, chemistry, pharmacology Limitations: Despite 'Clinical Study' in the title, the abstract reports no human trial. Abstract only read. Funding and conflicts: Not stated in the abstract. Read: abstract |
| UK legislation site (EU-origin text) 2026 Regulation (EC) No 1334/2008 on flavourings, Annex III (UK-published text on legislation.gov.uk, read 2026-10-25) legislation.gov.uk · Source |
Authoritative guidance n/a |
n/a | Beta-asarone as a naturally occurring flavouring substance n/a n/a n/a · vs n/a |
Annex III Part A lists beta-asarone among substances 'which shall not be added as such to food'. Part B sets a maximum of 1.0 mg/kg of beta-asarone in alcoholic beverages (the only beta-asarone entry in Part B in the text read). Beta-asarone may not be added as such to food; 1.0 mg/kg cap in alcoholic drinks Methods, limits and fundingOutcomes: Food flavouring rules Limitations: This is the UK-published version of the EU-origin text. The EU Official Journal copy could not be opened (the site did not return the page), so the current EU wording is NOT verified here. Other limits quoted in secondary sources (such as 0.1 mg/kg in some foods) were not found in the text read. Funding and conflicts: Government text. Read: full-text |
| US Government (Code of Federal Regulations) 2026 21 CFR 189.110: Calamus and its derivatives (eCFR, version dated 2026-10-20, read 2026-10-25) eCFR · Source |
Authoritative guidance n/a |
n/a | Calamus (dried rhizome of Acorus calamus L.), its oil and extract rhizome n/a n/a · vs n/a |
(b) 'Food containing any added calamus, oil of calamus, or extract of calamus is deemed to be adulterated in violation of the act' based on a Federal Register order of 9 May 1968 (33 FR 6967). (a) describes calamus as the dried rhizome of Acorus calamus L., used as a flavouring, especially as the oil or extract. (c) names an AOAC method for detecting oil of calamus (beta-asarone). Added calamus in food is deemed adulterated in the US Methods, limits and fundingOutcomes: Legal status in food Limitations: The text read covers food only. It does not itself discuss drugs, dietary supplements or the reasons for the 1968 order, so a wider 'food and drug ban' is NOT verified here. Funding and conflicts: Government text. Read: full-text |
| Uebel 2021 α-Asarone, β-asarone, and γ-asarone: Current status of toxicological evaluation. Journal of Applied Toxicology · PMID 33236787 · DOI |
Narrative review lab + animal (as reviewed) |
Published toxicology data on the asarone isomers (found in Acorus calamus and two other plants) | Asarone isomers (α, β, γ) n/a (compounds, mainly from calamus rhizome) n/a n/a · vs n/a |
Says efficacy and safety in humans are 'still not known'. Cardiotoxicity, liver toxicity, reproductive toxicity, mutagenicity and carcinogenicity were described for the propenyl isomers (α and β) 'with varying levels of reliability'. Officials restricted or gave advice on β-asarone and calamus preparations; α- and γ-asarone were not directly addressed because data are limited. Toxic signals for the propenyl asarones; no human data Methods, limits and fundingOutcomes: Cardiotoxicity, hepatotoxicity, reproductive toxicity, mutagenicity, carcinogenicity Limitations: Abstract only read. Toxicology data are described as rare and not critically reviewed this century before this paper. Numbers not in the abstract. Funding and conflicts: Not stated in the abstract. Read: abstract |
What we do not know yet
- No human trial of calamus rhizome, extract or oil was found for any use.
- No human data on cancer, liver injury, pregnancy or breastfeeding.
- No NCCIH, Health Canada, LiverTox, LactMed or HMPC monograph found; the EU wording of the beta-asarone limits and any US drug or supplement wording were not verified.
- Product testing for asarone content and contaminants is not available in the sources read.
How new research is added
New studies are found by a saved PubMed search and are placed in a review queue. A person reads each one before it changes any evidence rating.
Lab markers
What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".
Safety
What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.
Main points to know 8
- Cancer risk: beta-asarone and alpha-asarone are genotoxic and caused liver cancer in rodents. The European Medicines Agency says alpha- and beta-asarone, the main aromatic compounds in some calamus types, are genotoxic (they can damage DNA) and are liver carcinogens in rodents. A 2015 lab paper adds that beta-asarone also caused tumours of the small intestine in rodents. A 2021 toxicology review found heart, liver and reproductive toxicity, mutagenicity and carcinogenicity described for these compounds 'with varying levels of reliability', and says safety in people is still not known. No human cancer case was found in the sources read, but no human study looked either. Authoritative guidance 8 21 4
- The amount of asarone depends on the plant type, and a label rarely tells you. Calamus comes in diploid, triploid and tetraploid forms. In the EMA table the diploid American type had no asarone detected in leaf or rhizome oil, the triploid type had 9 to 19% beta-asarone in rhizome oil (and 50 to 65% in leaf oil), and the tetraploid Asian type had 85 to 95% in rhizome oil (4.4 to 8.3% of the dried rhizome). A 2005 lab study confirmed a diploid type with no beta-asarone and a triploid type with 11% in its extract. Growing conditions can also change the level of hazardous compounds in plants. The EMA said diploid types should always be preferred. Authoritative guidance 8 2 15
- Legal status: added calamus in food is deemed adulterated in the US; beta-asarone is capped in the EU/UK. US rule 21 CFR 189.110 says food containing any added calamus, oil of calamus or extract of calamus is deemed adulterated (based on a 1968 order). The text we read covers food only; we did not verify any wording on drugs or supplements. In EU-origin flavouring law (read on the UK-published copy) beta-asarone may not be added as such to food and is capped at 1.0 mg/kg in alcoholic drinks. In 2005 the EMA suggested asarone in herbal medicines be kept to a minimum with a temporary exposure limit of about 115 microgram a day. No newer EMA monograph was found. Authoritative guidance 20 19 8
- High amounts of calamus products caused prolonged vomiting; 'hallucinogenic' is a sales claim. Swedish poison centres took about 30 calls in 2003-2006 about people deliberately taking calamus products sold online as hallucinogenic. In seven cases urine tests found alpha- and beta-asarone. The main symptom reported was prolonged vomiting, sometimes for more than 15 hours. The researchers found no sign of the amphetamine-like compound sometimes claimed to cause hallucinations. The abstract does not describe hallucinations, so we cannot confirm them. Case series 3
- Skin: the oil is an irritant and a moderate sensitiser in lab models. A 2025 lab study classed one rhizome oil (about 41% beta-asarone) as a skin irritant (Category 2) and a moderate skin sensitiser (Category 1B), not corrosive. It was not tested on people. Laboratory research 7
- One negative bacterial test does not clear it. A 2025 Ames test of an Indian rhizome and pure beta-asarone found no mutation signal in five bacterial strains. The authors themselves call for chronic toxicity and cancer tests. It conflicts with earlier positive lab findings and does not cancel the rodent cancer data. Laboratory research 13 21
- Pregnancy and breastfeeding: avoid. Reproductive toxicity and possible teratogenicity are reported for asarones in animal and lab literature. No human pregnancy or lactation data were found, and no LactMed entry exists. With a carcinogenic, genotoxic compound this is a reason to avoid it. Narrative review 21 6
- Almost no human trials, so benefits are unproven. The traditional digestive and memory uses are not supported by human trials in the sources read. The only human study found used a homeopathic dilution and had no control group. Narrative review 18 16 1
Side effects 5
| Effect | How often | Severity and recovery | Evidence |
|---|---|---|---|
| Liver cancer (rodents) Human cancer risk is unknown, not shown to be zero. | Not given in the sources read; shown in rodent studies, not measured in people | severe Not applicable (cancer) | Authoritative guidance 8 21 |
| DNA damage (genotoxicity) Alpha-asarone is turned into mutagenic epoxides, mainly by liver enzyme CYP3A4, which the authors say is widely present in people. | Lab and animal findings; one 2025 Ames test negative | severe Not applicable | Laboratory research 8 13 5 |
| Prolonged vomiting after large intake of calamus products Sometimes lasted more than 15 hours. | Main symptom in the Swedish poison-centre series (about 30 enquiries) | moderate Not described in the abstract | Case series 3 |
| Skin irritation and sensitisation (oil) Rhizome oil about 41% beta-asarone. | Predicted from lab models; no human patch tests | mild Irritation reversible in the lab skin models | Laboratory research 7 |
| Heart, reproductive and developmental toxicity No human data. | Reported for asarones in animals/lab 'with varying levels of reliability' | unknown Not described | Narrative review 21 6 |
Liver
No LiverTox entry for calamus or asarone was found (a Bookshelf search for calamus, acorus, sweet flag and asarone returned nothing relevant). No human case of calamus liver injury was found in the sources read. In animals asarones cause liver tumours, and a 2023 review says the epoxide metabolites of alpha- and beta-asarone may be toxic to the liver. In human liver enzyme tests beta-asarone follows the same epoxide pathway as in animals. 8 10 4 5
How often. No rate. Human liver data were not found.
Monitoring. No agency monitoring advice was found.
This is a safety connection. It is not evidence that Calamus supports liver health.
Medicines and supplements 4
| With | Why it matters | Importance | Evidence | What to do |
|---|---|---|---|---|
| Blood thinners (warfarin and similar) and anti-clotting medicines prescription | The EMA lists an anticoagulant effect of asarone in mice and rats. Nothing is known in people. | Unknown. Animal signal only. | Animal research Very low certainty 8 | No human interaction study exists. Tell your doctor or pharmacist about any calamus product if you take a blood thinner or have surgery planned. |
| Medicines broken down by liver enzymes CYP3A4 or CYP2D6 prescription | In test-tube assays a standardised extract and alpha-asarone blocked CYP3A4 and CYP2D6 (moderate interaction potential). CYP3A4 is also the main enzyme that activates alpha-asarone to mutagenic epoxides. | Unknown. Test-tube concentrations are not body doses. | Laboratory research Very low certainty 14 5 | Ask a pharmacist before combining with any prescription medicine. |
| Sedatives, sleep medicines, alcohol and other medicines that cause drowsiness other | Sedative and CNS-depressant effects are reported in rats and listed in a review. An added effect is theoretical. | Unknown. Theoretical. | Pharmacological theory Very low certainty 8 16 | No human data; ask a doctor or pharmacist. |
| Other liver-stressing herbs or medicines herb | Not studied. Mentioned only because asarones are liver carcinogens in rodents. | Unknown; no human study found. | Pharmacological theory Not enough evidence 8 | Avoid combining with other products that may harm the liver unless a doctor agrees. |
Who should check first 7
| Situation | Advice | Evidence |
|---|---|---|
| Pregnancy | Avoid. Reproductive toxicity and possible teratogenicity are reported for asarones in animal and lab literature; no human data. | Narrative review 21 6 |
| Breastfeeding | Avoid. No lactation data and no LactMed entry were found. | Insufficient 21 |
| Babies and children | Not recommended on the evidence read: Vacha is traditionally given to infants for brain development, but no safety data exist and the compounds are carcinogenic in rodents. Ask a paediatrician. | Traditional use 13 21 |
| Liver disease or taking medicines that affect the liver | Avoid; asarones are liver carcinogens in rodents and no human liver data exist. | Authoritative guidance 8 |
| On blood thinners or having surgery | Talk to your doctor first; an anticoagulant effect was seen in mice and rats. | Animal research 8 |
| Sensitive or allergic skin (oil) | Avoid applying the oil; it was a moderate sensitiser and irritant in lab models. | Laboratory research 7 |
| Seizure disorders | Do not use calamus in place of seizure medicine; the anticonvulsant effect is from animal work only. | Animal research 6 |
Overdose, product quality and regulators
Summary. The rhizome (and the oil made from it) is the part used. The harm in the sources read is long-term and cancer-related, from alpha- and beta-asarone, plus acute vomiting after large intake of calamus products. How much beta-asarone a product holds depends on the plant type.
Animal. Alpha- and beta-asarone are genotoxic and cause liver cancer in rodents (EMA); beta-asarone also caused small-intestine tumours in rodents; alpha-asarone's epoxide metabolites are thought to cause liver cancer in male mice.
Human doses studied. No dose-ranging study was found. Poisoning-series amounts are not given in the abstract.
High dose or long term signals. Prolonged vomiting after large intake (Swedish series). Long-term human effects not studied.
Overdose response. Not covered in the sources read. Seek medical advice for severe vomiting after calamus products.
Genotoxicity. Positive in several lab systems per the EMA and reviews; one 2025 Ames test of Indian rhizome and beta-asarone was negative.
Toxic plant parts. Rhizome and leaf oils both contain asarones; in the triploid type the EMA table shows more beta-asarone in leaf oil (50-65%) than rhizome oil (9-19%). In the tetraploid type rhizome oil is 85-95%.
No pesticide, heavy-metal or microbe testing of calamus products was found. The main product-quality issues found are asarone content that varies by plant type and growing conditions, and confusion between Acorus species.
Variable beta-asarone content. Asarone ranges from not detected (diploid) to 85-95% of rhizome oil (tetraploid), and environment and genetics change hazardous-compound levels in plants. 8 2 15
Species mix-ups. A. gramineus, A. calamus and A. tatarinowii can be confused in markets; Korean researchers designed DNA tests to tell them apart. How often mix-ups happen was not in the abstract. GBIF treats A. tatarinowii as a synonym of A. calamus var. angustatus, while Chinese medicine treats shi chang pu as its own herb. 17 9
Ayurvedic purification (Shodhana). Ayurveda uses a purification process for calamus, named as a toxic plant because of beta-asarone; the abstract gives no measured reduction. 11
| Body | Action | Date |
|---|---|---|
| US Food and Drug Administration (21 CFR 189.110) (United States) | Food containing any added calamus, oil of calamus or extract of calamus is deemed adulterated, based on a Federal Register order of 9 May 1968. Wider drug or supplement wording was not found in the text read. source | 1968 order; regulation text version 2026-10-20 |
| European Medicines Agency (HMPC working party) (European Union) | 2005 public statement: alpha- and beta-asarone are genotoxic and hepatocarcinogens in rodents; keep asarone in herbal medicines to a minimum; always prefer diploid types; a temporary limit of about 115 microgram a day (about 2 microgram per kg a day) could be accepted until a full benefit/risk assessment. source | 2005 |
| EU flavourings regulation (UK-published copy on legislation.gov.uk) (EU-origin law (UK text)) | Beta-asarone is listed among substances which shall not be added as such to food (Annex III Part A) and capped at 1.0 mg/kg in alcoholic beverages (Part B). source | Regulation (EC) No 1334/2008 |
When to get medical help
- Vomiting that will not stop after taking a calamus product, or signs of dehydration: get medical help (general medical advice; the Swedish series reported vomiting lasting over 15 hours).
- Yellow skin or eyes, dark urine, or ongoing upper-right belly pain: see a doctor (general advice for possible liver trouble; no calamus liver case was found).
- Spreading skin rash, swelling or blistering after using the oil: stop and see a doctor.
- Hallucinations, severe confusion or fits after using a calamus product: seek emergency care.
- Pregnant or possibly pregnant after taking calamus: contact your doctor or midwife.
Stop the supplement and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.
General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.
Frequently asked questions
What is calamus (sweet flag)?
Is calamus safe?
No safe use has been established. The European Medicines Agency says alpha- and beta-asarone from calamus are genotoxic and cause liver cancer in rodents. A 2021 review says safety in people is still not known. Pregnant and breastfeeding women, children and people with liver disease should avoid it.
Does calamus cause cancer?
In rodents, yes: asarones caused liver tumours (and beta-asarone also small-intestine tumours in one summary). No human cancer study was found, so the risk in people is unknown rather than shown to be zero. One 2025 bacterial test of an Indian rhizome was negative, and its authors still ask for long-term cancer tests.
Is calamus banned?
In the US, food with any added calamus, its oil or its extract is deemed adulterated (21 CFR 189.110, based on a 1968 order). The text we read covers food only. In the EU-origin flavouring law (UK-published copy), beta-asarone may not be added as such to food and is capped at 1.0 mg/kg in alcoholic drinks. We did not find Health Canada or NCCIH pages.
Why do calamus products differ so much?
The amount of beta-asarone depends on the plant type. The EMA table shows none detected in the diploid American type, 9 to 19% of rhizome oil in the triploid type and 85 to 95% in the tetraploid Asian type. A label rarely says which type is inside, which is why the EMA said diploid types should always be preferred.
Is calamus a hallucinogen?
It is sometimes sold online that way. In 30 Swedish poison-centre enquiries, the main symptom reported was prolonged vomiting, sometimes over 15 hours, and the researchers found no sign of the amphetamine-like compound claimed to cause hallucinations. The abstract does not describe hallucinations.
Is it safe in pregnancy or breastfeeding?
Does calamus interact with medicines?
Does it help memory or digestion?
Is Vacha the same as the Chinese herb shi chang pu?
Not on this page. Vacha is Acorus calamus. Shi chang pu is usually Acorus tatarinowii, a related plant used in Chinese medicine that is not covered here. Naming databases disagree: GBIF lists A. tatarinowii as a synonym of A. calamus var. angustatus, and DNA tests were designed to tell the Acorus species apart.
Is the oil safe on the skin?
A 2025 lab study classed one rhizome oil (about 41% beta-asarone) as a skin irritant and a moderate skin sensitiser. It was not tested on people.
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Editorial transparency
- Written by
- AlternativeMed editorial team. Research compiled with AI assistance, then checked against PubMed records.
- Medical review
- None. This page has not been reviewed by a physician or pharmacist.
- First published
- 2026-10-25
- Last substantive update
- 2026-10-25
- How we research
- We searched PubMed and read abstracts of 17 PubMed papers; read the full EMA asarone statement, the US rule 21 CFR 189.110 and the UK-published EU flavourings annex; checked the plant name in GBIF and NCBI Taxonomy and compound IDs in PubChem. NCCIH, Health Canada, LiverTox, LactMed and an HMPC monograph were not found.
- How we rate evidence
- See "How we rate evidence" in the Evidence tab.
- Independence
- No product is promoted on this page. No affiliate links are shown, and none will be added for calamus.
Sources 21
Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.
- Azis SP, Sehgal C, Chakraborty PS, et al. Exploring the Homeopathic Therapeutic Potential of Acorus calamus: A Multi-center Open-Label Clinical Verification Study.. Homeopathy. 2026. PMID 40921187. DOI 10.1055/a-2625-0202. (abstract)
- Bertea CM, Azzolin CM, Bossi S, et al. Identification of an EcoRI restriction site for a rapid and precise determination of beta-asarone-free Acorus calamus cytotypes.. Phytochemistry. 2005. PMID 15721942. DOI 10.1016/j.phytochem.2005.01.007. (abstract)
- Björnstad K, Helander A, Hultén P, et al. Bioanalytical investigation of asarone in connection with Acorus calamus oil intoxications.. Journal of Analytical Toxicology. 2009. PMID 20040135. DOI 10.1093/jat/33.9.604. (abstract)
- Cartus AT, Stegmüller S, Simson N, et al. Hepatic metabolism of carcinogenic β-asarone.. Chemical Research in Toxicology. 2015. PMID 26273788. DOI 10.1021/acs.chemrestox.5b00223. (abstract)
- Cartus AT, Schrenk D. Metabolism of carcinogenic alpha-asarone by human cytochrome P450 enzymes.. Naunyn-Schmiedeberg's Archives of Pharmacology. 2020. PMID 31485694. DOI 10.1007/s00210-019-01724-0. (abstract)
- Chellian R, Pandy V, Mohamed Z. Pharmacology and toxicology of α- and β-Asarone: A review of preclinical evidence.. Phytomedicine. 2017. PMID 28732807. DOI 10.1016/j.phymed.2017.04.003. (abstract)
- Desai KR, Ranade JR, Nagane RM, et al. Comprehensive In Vitro Safety Assessment of Acorus calamus Rhizome Oil Using OECD-Compliant New Approach Methods: Classification as a GHS Category 1B Sensitiser and Category 2 Irritant.. Toxics. 2025. PMID 41441227. DOI 10.3390/toxics13121006. (abstract)
- European Medicines Agency. EMEA (HMPC working party): Public statement on the use of herbal medicinal products containing asarone (2005). European Medicines Agency. 2005. (full-text)
- GBIF. GBIF Backbone Taxonomy: Acorus calamus L. (species match, synonyms and related names, retrieved 2026-10-25). GBIF. 2026. (full-text)
- He X, Chen X, Yang Y, et al. Acorus calamus var. angustatus Besser: Insight into current research on ethnopharmacological use, phytochemistry, pharmacology, toxicology, and pharmacokinetics.. Phytochemistry. 2023. PMID 36871902. DOI 10.1016/j.phytochem.2023.113626. (abstract)
- Maurya SK, Seth A, Laloo D, et al. Śodhana: An Ayurvedic process for detoxification and modification of therapeutic activities of poisonous medicinal plants.. Ancient Science of Life. 2015. PMID 26283803. DOI 10.4103/0257-7941.160862. (abstract)
- NCBI PubChem. PubChem compound records: alpha-asarone (CID 636822), beta-asarone (CID 5281758), gamma-asarone (CID 636750), 2,4,5-trimethoxycinnamic acid (CID 688363); retrieved 2026-10-25. PubChem. 2026. (full-text)
- Narayana DBA, Mukne A. Reporting negative Ames test results for Indian Acorus calamus L., rhizome, extracts, and beta asarone.. Indian Journal of Pharmacology. 2025. PMID 40844059. DOI 10.4103/ijp.ijp_391_24. (abstract)
- Pandit S, Mukherjee PK, Ponnusankar S, et al. Metabolism mediated interaction of α-asarone and Acorus calamus with CYP3A4 and CYP2D6.. Fitoterapia. 2011. PMID 21062640. DOI 10.1016/j.fitote.2010.11.009. (abstract)
- Prinsloo G, Ojo O, Rietjens IMCM. Environmental and internal drivers of genotoxic carcinogens accumulation in botanicals and their preparations.. Archives of Toxicology. 2025. PMID 40646165. DOI 10.1007/s00204-025-04123-y. (abstract)
- Rajput SB, Tonge MB, Karuppayil SM. An overview on traditional uses and pharmacological profile of Acorus calamus Linn. (Sweet flag) and other Acorus species.. Phytomedicine. 2014. PMID 24200497. DOI 10.1016/j.phymed.2013.09.020. (abstract)
- Ryuk JA, Kim YS, Lee HW, et al. Identification of Acorus gramineus, A. calamus, and A. tatarinowii using sequence characterized amplified regions (SCAR) primers for monitoring of Acori graminei rhizoma in Korean markets.. International Journal of Clinical and Experimental Medicine. 2014. PMID 25356101. (abstract)
- Sharma V, Sharma R, Gautam DS, et al. Role of Vacha (Acorus calamus Linn.) in Neurological and Metabolic Disorders: Evidence from Ethnopharmacology, Phytochemistry, Pharmacology and Clinical Study.. Journal of Clinical Medicine. 2020. PMID 32325895. DOI 10.3390/jcm9041176. (abstract)
- UK legislation site (EU-origin text). Regulation (EC) No 1334/2008 on flavourings, Annex III (UK-published text on legislation.gov.uk, read 2026-10-25). legislation.gov.uk. 2026. (full-text)
- US Government (Code of Federal Regulations). 21 CFR 189.110: Calamus and its derivatives (eCFR, version dated 2026-10-20, read 2026-10-25). eCFR. 2026. (full-text)
- Uebel T, Hermes L, Haupenthal S, et al. α-Asarone, β-asarone, and γ-asarone: Current status of toxicological evaluation.. Journal of Applied Toxicology. 2021. PMID 33236787. DOI 10.1002/jat.4112. (abstract)