Herbs & Botanicals · Deadly poisonous plant

Hemlock

Conium maculatum · also called Poison hemlock

Hemlock, or poison hemlock, is a carrot-family plant that is one of the most dangerous in the world. Every part is poisonous. It has been used in old medicine and was the poison of Socrates, but there is no safe medicinal use today. If anyone may have eaten it, call Poison Control (US 1-800-222-1222) or emergency services right away.

General information, not medical advice. Last substantive update October 25, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

About Hemlock

Poison hemlock (Conium maculatum) is a very poisonous carrot-family plant. It is not a medicine. Poisonings come mostly from mistaking it for food plants.

Safety first

Poison hemlock is among the most poisonous plants. Every part, including leaves, seeds and root, contains poison. Eating it can cause vomiting, trembling, then paralysis and failure of the breathing muscles. People and livestock have died.

If you or someone else may have eaten it, or breathed smoke from burning it, call Poison Control (US 1-800-222-1222) or your emergency number now. Do not wait for symptoms. Do not use it as a herb in any form.

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How poisonings happen

Case reports describe people mistaking hemlock for celery, parsnip, parsley or wild carrot. We do not give identification tips, because a checklist can fail. Never forage wild plants of the carrot family unless an expert identifies them in person.

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Not water hemlock, and not the hemlock tree

Water hemlock (Cicuta) and hemlock water-dropwort (Oenanthe) are different plants. Their toxins cause seizures, and even a small amount can be severe. The hemlock tree (Tsuga) is an unrelated conifer. Hemlock is also a different plant from the herbs ground elder and lovage, which are covered on their own pages.

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History

Hemlock was used as an execution poison in ancient Greece. A 2024 paper judges the death of Socrates a likely case of hemlock poisoning. Old medicine is said to have used it as a sedative and antispasmodic, but we could not verify that in the sources we read.

Coniine, its main poison, was the first alkaloid whose structure was worked out (1881) and the first made in the lab (1886).

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What is in it

The poisons are piperidine alkaloids: coniine, gamma-coniceine and N-methylconiine, plus others. They act on nicotinic receptors, first over-stimulating and then blocking nerve-to-muscle signals. Amounts vary with the plant's age and conditions, which makes any plant unpredictable.

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What the research shows

There is no clinical trial of hemlock for any use. Research is case reports of poisoning, lab and animal studies, and history. A review mentions research interest in coniine for pain, which is only an idea. A drug tested as a rescue treatment made poisoning signs worse in goats.

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Other cautions

Livestock poisoned in certain stages of pregnancy have young with cleft palate and joint deformities. Effects in human pregnancy are not established, but avoid any exposure. Keep children and pets away. Hospital care is supportive; no antidote is known.

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At a glance

Traditional uses history, not proof

Historical sedative and antispasmodic (not verified)
Execution poison in ancient Greece

Studied for research

No benefit shown: insufficient evidence for every use
Antidote search: against (made goats worse)

Main compounds

Coniine
Gamma-coniceine
N-methylconiine

Common forms

No safe preparation exists

Research links: Review: poison hemlock (PubMed) · Review: nicotinic plant poisoning (PubMed) · Case report: shared hemlock meal, 2026 (PubMed) · Death of Socrates, 2024 (PubMed) · Research Library · Genes & Biomarkers Library

The plant and its history

Accepted scientific name: Conium maculatum L.
Naming authority: GBIF species match read 2026-10-25: ACCEPTED, EXACT match, usageKey 3034807, confidence 99.
Common names: Hemlock (English); Poison hemlock (English); Cicuta (do not confuse; this is the water hemlock genus) (Latin)
Botanical family: Apiaceae (the carrot or parsley family).
Classification: Plantae > Apiales > Apiaceae > Conium > Conium maculatum
Native range: Europe, Western Asia and North Africa (stated in a 2026 case series); now a widespread weed elsewhere.
Habitat: A common weed of disturbed ground (nitrophile weed, per Vetter 2004).
What the plant looks like: Roots: Not described on purpose.; Stems: Not described on purpose.; Leaves: Not described on purpose.; Flowers: Not described on purpose.; Fruit: Not described on purpose.
Cultivation: Not covered. Not a plant to grow for use.
Harvest and processing: Not covered. No harvest or preparation is described.
Look-alikes and adulterants: Name: Edible carrot-family plants (wild carrot, parsnip, parsley, celery, fennel, anise); Note: Poisonings are reported after hemlock was mistaken for these. We give no identification tips on purpose. Never forage wild carrot-family plants unless an expert identifies them in person.; Name: Water hemlock (Cicuta) and hemlock water-dropwort (Oenanthe); Note: Different plants with a different poison that causes seizures. Both are also deadly.; Name: Hemlock tree (Tsuga); Note: An unrelated conifer tree. General knowledge, not source-checked here.
Sustainability and conservation: Not covered.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Ancient Greece	Used as a state execution poison; the death of Socrates (399 BCE) is judged a likely hemlock poisoning (2024 paper).	p38348840
Chemistry	Coniine was the first alkaloid whose structure was worked out (1881) and the first made in the lab (1886).	p29135964
Old European medicine	Reported historical use as a sedative and antispasmodic. NOT verified: no source we read documents it.	none
Portugal, river fishing	A 2025 case report says the plant is used as an old technique for stunning fish in rivers.	p40248547

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
Coniine PubChem 441072	piperidine alkaloids	Mature plant and seed	Blocks nicotinic receptors; main cause of poisoning. ^{13 4 9 16}	Animal research
Gamma-coniceine PubChem 442632	piperidine alkaloids	Early growth	Precursor of the other hemlock alkaloids; the most potent of the group tested on muscle-type receptors. ^{6 9 16}	Animal research
N-methylconiine PubChem 169683	piperidine alkaloids	Not specified	Less lethal than gamma-coniceine in mice; the forms differ in potency. ^{6 16}	Animal research
Conhydrine and pseudoconhydrine	piperidine alkaloids	Not specified	Listed as hemlock alkaloids. PubChem IDs not looked up. ¹³	Review

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Nicotinic acetylcholine receptors	Nicotinic receptors, including muscle type	The alkaloids first over-stimulate then block nerve-to-muscle signalling, leading to paralysis and respiratory failure. ^{10 4 6}	Human case reports and animal
Developing fetus (livestock)	Not specified	Reduced fetal movement is thought to cause cleft palate and contracted joints in animals (the review links these to piperidine alkaloids). ^{2 7}	Animal research

Absorption, metabolism and elimination

Absorption: Nicotine-like alkaloids are absorbed readily by all routes (stated for the group).
Distribution: They cross the blood-brain barrier and placenta and enter breast milk (group statement).
Metabolism: Mostly in the liver (group statement); hemlock-specific data not found.
Elimination: Rapid kidney elimination (group statement).
Bioavailability: Not established.

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Isolated compounds versus whole extracts

Mouse tests of pure alkaloids differ in potency (gamma-coniceine more toxic than N-methylconiine). The whole plant mixes several alkaloids whose proportions change with plant age and conditions, so the risk of any plant is unpredictable.

Nutritional composition

Not a food or nutrient. Not edible.

5benefits and uses looked at

17studies and sources checked

Not enough evidencebest evidence rating found

0lab markers tracked in trials

4 not enough evidence1 evidence against

What is Hemlock good for?

Hemlock has no tested benefit. The rows show old claims and research ideas, and how weak the evidence is.

Sedative use (historical)Not enough evidenceOld medicine used it, but we found no source or trial. It is not a safe sedative. Muscle spasm (historical)Not enough evidenceUnverified historical claim. No trial. It can paralyse the breathing muscles. Pain reliefNot enough evidenceA review mentions research interest in coniine only. Nothing in people. Poison of SocratesNot enough evidenceHistory, not a benefit. A 2024 paper judges the death of Socrates a likely hemlock poisoning. AntidoteEvidence againstNo antidote exists. A drug tested in goats made poisoning signs worse.

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.

Calming the nerves (historical sedative use)

Not enough evidence

Hemlock was once used in old medicine as a sedative. Today there is no safe or approved medicinal use. The same alkaloids that dull nerves can stop the breathing muscles.

2 studiesNot applicable. No amount, preparation or form is recommended and non…

Studies, doses and limits

What the trials found

None. No clinical trial of any hemlock preparation as a sedative was found.

Results

None.

Effect sizes as reported

None.

Why this rating

Historical use only, not verified here. The margin between an effect and death is not known to be safe in any preparation.

Form and dose studied

Not applicable. No amount, preparation or form is recommended and none is described.

Who was studied

Not applicable

Limits

No trial, no safe preparation, and no approved use.

Why researchers looked

Historical medicine reached for hemlock because it quiets nerve and muscle activity.

Traditional use

We found no source in this round that documents the historical sedative use in detail. The claim is from general medical history and is NOT verified here.

Proposed mechanism Pharmacological theory

Coniine and related alkaloids act on nicotinic receptors (first stimulating, then blocking nerve-to-muscle signals). A calming effect and a lethal effect come from the same action.

A proposed mechanism does not show that the effect happens in people.

Poison hemlock is among the most dangerous plants. Do not eat, drink, smoke or apply it. See the safety tab.

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Poison of Socrates (history, not a benefit)

Not enough evidence

The ancient Greek philosopher Socrates is thought to have been executed with poison hemlock. A 2024 paper judges this a likely case of hemlock poisoning. This is history and shows how dangerous the plant is.

1 studiesNot applicable. No amount, preparation or form is recommended and non…

Studies, doses and limits

What the trials found

A historical analysis, not a clinical study.

Results

The author accepts the death as a limited case report of poison hemlock poisoning.

Effect sizes as reported

None.

Why this rating

A historical reading of a text written later from other people's accounts.

Form and dose studied

Not applicable. No amount, preparation or form is recommended and none is described.

Who was studied

One historical person

Limits

Not clinical evidence; it says nothing about any benefit.

Why researchers looked

It explains why hemlock is famous and why its action on nerves has been studied.

Traditional use

Described in Plato's Phaedo; the death took place in 399 BCE.

Proposed mechanism Human case report

Paralysis of nerve-to-muscle signalling, leading to failure of breathing.

A proposed mechanism does not show that the effect happens in people.

Poison hemlock is among the most dangerous plants. Do not eat, drink, smoke or apply it. See the safety tab.

Pain relief (a research idea only)

Not enough evidence

A 2017 review says there is renewed interest in medical uses of coniine, especially for pain relief without addiction. We found no study in people. Do not take hemlock for pain.

2 studiesNot applicable. No amount, preparation or form is recommended and non…

Studies, doses and limits

What the trials found

None. No trial in people.

Results

Interest is stated in a review; no data are given in the abstract.

Effect sizes as reported

None.

Why this rating

An idea in a review. No human data.

Form and dose studied

Not applicable. No amount, preparation or form is recommended and none is described.

Who was studied

Not applicable

Limits

Lab-stage idea only. Lethal doses in mice are low (about 5.5 mg/kg for coniine).

Why researchers looked

Coniine acts on nicotinic receptors, which are involved in pain signalling.

Traditional use

No traditional claim verified here.

Proposed mechanism Lab animal

Receptor blocking by coniine in cells and animals.

A proposed mechanism does not show that the effect happens in people.

Poison hemlock is among the most dangerous plants. Do not eat, drink, smoke or apply it. See the safety tab.

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Muscle spasm and convulsions (historical use)

Not enough evidence

Old herbals used hemlock for muscle spasms and convulsive illnesses. We found no source we could read that confirms this, and no study. It is not a safe medicine today.

2 studiesNot applicable. No amount, preparation or form is recommended and non…

Studies, doses and limits

What the trials found

None.

Results

None.

Effect sizes as reported

None.

Why this rating

Historical claim, not verified, no trial.

Form and dose studied

Not applicable. No amount, preparation or form is recommended and none is described.

Who was studied

Not applicable

Limits

No trial; risk of fatal paralysis.

Why researchers looked

Hemlock paralyses muscle signalling, so old medicine tried it for spasm.

Traditional use

NOT verified here; stated from general medical history and the project brief only.

Proposed mechanism Pharmacological theory

Blocks nerve-to-muscle signals; the same action stops breathing muscles.

A proposed mechanism does not show that the effect happens in people.

Poison hemlock is among the most dangerous plants. Do not eat, drink, smoke or apply it. See the safety tab.

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A drug to treat hemlock poisoning (tested in goats)

Evidence against

Researchers tested varenicline, a drug that acts on the same receptors, as a possible rescue treatment. It did not help goats given poison hemlock and made signs worse. Treatment of poisoning in people is supportive hospital care.

2 studiesNot applicable. No amount, preparation or form is recommended and non…

Studies, doses and limits

What the trials found

None. Animal and cell study only.

Results

Mouse lethal dose for coniine 5.5 mg/kg rose to 9.1 mg/kg with varenicline. Goat signs were made worse.

Effect sizes as reported

None.

Why this rating

In the only animal test found, the drug did not help and made signs worse.

Form and dose studied

Not applicable. No amount, preparation or form is recommended and none is described.

Who was studied

Cells, mice, goats

Limits

Not a treatment for people. No antidote is established.

Why researchers looked

There is no antidote for hemlock poisoning, so researchers looked for one.

Traditional use

Not applicable

Proposed mechanism Animal research

Varenicline competes at nicotinic receptors; it shifted lethal doses in mice slightly but worsened goats' signs.

A proposed mechanism does not show that the effect happens in people.

If poisoned, call Poison Control (US 1-800-222-1222) or emergency services at once.

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Connections to the rest of health

How Hemlock 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

Kind of connection Connected to Search

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Respiratory system		Case report	Paralysis of breathing muscles can be fatal. Preparation or compound: Poison hemlock (coniine and relatives)	^{12 10}
Nervous system		Case report	Nicotine-like stimulation then paralysis. Preparation or compound: Poison hemlock (coniine and relatives)	^{10 8}
Reproductive system		Animal	Birth defects in livestock. Preparation or compound: Poison hemlock	^{2 7}
Nervous System	Biological association	Not enough evidence	Studied for: Calming the nerves (historical sedative use) Studied for: Poison of Socrates (history, not a benefit)	^{4 10 1 3 7 5}

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Coniine	Biological association	Animal	Blocks nicotinic receptors; main cause of poisoning. Preparation or compound: Mature plant and seed	^{13 4 9 16}
Gamma-coniceine	Biological association	Animal	Precursor of the other hemlock alkaloids; the most potent of the group tested on muscle-type receptors. Preparation or compound: Early growth	^{6 9 16}
N-methylconiine	Biological association	Animal	Less lethal than gamma-coniceine in mice; the forms differ in potency. Preparation or compound: Not specified	^{6 16}
Conhydrine and pseudoconhydrine	Biological association	Review	Listed as hemlock alkaloids. PubChem IDs not looked up. Preparation or compound: Not specified	¹³

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 Hemlock. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Calming the nerves (historical sedative use) 2 studies Not enough evidence Poison of Socrates (history, not a benefit) 1 studies Not enough evidence Pain relief (a research idea only) 2 studies Not enough evidence Muscle spasm and convulsions (historical use) 2 studies Not enough evidence A drug to treat hemlock poisoning (tested in goats) 2 studies Evidence against

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 read our existing herb summary, searched PubMed, read the abstract of each PubMed record cited, and checked the plant name in GBIF and compounds in PubChem.

Study library: every study we checked 17

Design Research type Plant part Year from Search

Study	Design	People	Product, dose, length	Result
Dayan 2024 Death of Socrates: a likely case of poison hemlock (Conium maculatum) poisoning. Clin Toxicol (Phila) · PMID 38348840 · DOI	Historical analysis	Historical account (399 BCE, Plato's Phaedo)	Poison hemlock extract (as described in the history) Not stated Not given here Not given here · vs Not applicable	Argues that the death of Socrates can be accepted as a limited case report of poison hemlock poisoning, after reinterpreting the Greek terms. Unpleasant effects (vomiting, belly pain, muscle twitching) may have been left out of the account on purpose. Not applicable Methods, limits and funding Outcomes: Fit between the ancient account and modern poisoning reports Limitations: A historical interpretation based on a text written later from other people's accounts. Not clinical evidence. Funding and conflicts: No funding stated in the abstract. Read: abstract
Green 2012 Piperidine alkaloids: human and food animal teratogens. Food Chem Toxicol · PMID 22449544 · DOI	Narrative review review	Review of livestock and human data	Piperidine alkaloids from poison hemlock, lupine and tobacco Whole plants and alkaloids Not given here Not given here · vs Not applicable	Piperidine alkaloids cause limb and joint deformities (multiple congenital contractures) and cleft palate in the young of cattle, pigs, sheep and goats. In people, maternal tobacco use is linked with oral clefts, and the authors suggest this may be partly due to related alkaloids. Hemlock itself is not shown to do this in people. Not applicable Methods, limits and funding Outcomes: Birth defects Limitations: Narrative review. A human link to hemlock is a hypothesis, not shown. Read: abstract
Green 2024 The actions of varenicline on alkaloids from Conium maculatum (poison hemlock), Lupinus sulphureus (sulphur lupine) and Nicotiana glauca (tree tobacco). Toxicon · PMID 39577702 · DOI	Animal and cell study animal	Cultured cells, mice and goats	Pure alkaloids (coniine, gamma-coniceine, anabasine), plant alkaloid extracts, and varenicline Alkaloids; poison hemlock fed to goats Not given here Not given here · vs Not applicable	In mice the median lethal doses were 5.5 mg/kg for coniine and 3.7 mg/kg for gamma-coniceine. Varenicline raised these only slightly (to 9.1 and 4.3 mg/kg). In goats given poison hemlock, varenicline made the signs of poisoning worse and was judged not useful. Not applicable Methods, limits and funding Outcomes: Cell response, lethal dose in mice, signs in goats Limitations: Animal and cell work. Not a treatment for people. Authors work for the US Department of Agriculture. Read: abstract
Hotti 2017 The killer of Socrates: Coniine and Related Alkaloids in the Plant Kingdom. Molecules · PMID 29135964 · DOI	Narrative review review	Review of chemistry and biology	Coniine and related alkaloids Plant Not given here Not given here · vs Not applicable	Coniine is a nicotinic receptor blocker and causes death by suffocation in mammals. It was the first alkaloid whose structure was worked out (1881) and the first synthesised (1886). Besides poison hemlock it occurs in some pitcher plants and Aloe species. The authors mention renewed interest in medical uses, particularly pain relief without addiction, which is a research idea only. Not applicable Methods, limits and funding Outcomes: Chemistry, plant biology, medical interest Limitations: Narrative review; the pain-relief interest has no clinical data behind it here. Funding and conflicts: No conflict of interest declared. Read: abstract
Karakasi 2019 Conium maculatum intoxication: Literature review and case report on hemlock poisoning. Forensic Sci Rev · PMID 30594904	Case series and review review	Three poisoning incidents (one fatal) plus literature review	Poison hemlock Not specified Not given here Not given here · vs Not applicable	Poisoning is relatively rare but life-threatening. Most patients in the literature were men over 38. The course includes tremor, vomiting, muscle and respiratory paralysis, muscle breakdown (rhabdomyolysis) and acute kidney failure. Management is reducing absorption, close watching and breathing support. Survival is high with prompt treatment and recovery usually takes a few days. Not applicable Methods, limits and funding Outcomes: Symptoms, risk factors, management Limitations: Small series. Abstract has no DOI. Read: abstract
Lee 2013 Stereoselective potencies and relative toxicities of γ-coniceine and N-methylconiine enantiomers. Chem Res Toxicol · PMID 23514442 · DOI	Lab and animal study animal	Cells with human muscle-type nicotinic receptors; mice	Synthetic gamma-coniceine and N-methylconiine Lab-made alkaloids Not given here Not given here · vs Not applicable	Gamma-coniceine was the most potent of these alkaloids on the muscle-type receptor. Mouse lethal doses were 4.4 mg/kg for gamma-coniceine and 16.1 to 19.2 mg/kg for the N-methylconiine forms. Not applicable Methods, limits and funding Outcomes: Receptor potency, lethal dose in mice Limitations: Lab and mouse data only. Read: abstract
López 1999 Biochemistry of hemlock (Conium maculatum L.) alkaloids and their acute and chronic toxicity in livestock. A review. Toxicon · PMID 10340826 · DOI	Narrative review review	Review of livestock literature	Poison hemlock Vegetative and flowering plant and seeds Not given here Not given here · vs Not applicable	Eight piperidine alkaloids occur; gamma-coniceine and coniine account for most toxicity. Acute poisoning blocks nerve-muscle signals and kills when breathing muscles fail. In pregnant animals poisoned during organ formation, young are born with cleft palate or contracted joints; this damage is irreversible. No specific antidote exists. Alkaloids can pass into milk and poultry meat. Poisoned animals may return to eat the plant. Not applicable Methods, limits and funding Outcomes: Acute and chronic toxicity in animals Limitations: Livestock review; effects in people are not established. Read: abstract
Nunes 2025 Acute Intoxication With Poison Hemlock (Conium maculatum). Cureus · PMID 40248547 · DOI	Case report	2 Two people poisoned by poison hemlock in Portugal	Poison hemlock plant (piperidine alkaloids) Plant material (part not stated in abstract) Not given here Not given here · vs Not applicable	Describes a nicotine-like picture with an early over-stimulation phase and a later inhibitory phase. Death comes from respiratory arrest and circulatory collapse. Both patients recovered fully with rapid diagnosis and supportive care. The authors note the plant is easily mistaken for celery, parsnip leaves or carrot roots. Not applicable Methods, limits and funding Outcomes: Clinical picture, outcome Limitations: Two cases only. Not a measure of how often poisoning is fatal. Funding and conflicts: No funding or conflicts declared. Read: abstract
Panter 1988 Toxicoses in livestock from the hemlocks (Conium and Cicuta spp.). J Anim Sci · PMID 3049497 · DOI	Narrative review review	Review of livestock poisoning	Poison hemlock and water hemlock All parts of poison hemlock Not given here Not given here · vs Not applicable	In poison hemlock the main toxins are coniine (mature plant and seed) and gamma-coniceine (early growth). Signs in livestock: weakness, trembling, early stimulation then depression and death by respiratory paralysis. Skeletal defects occur in young of cattle, pigs and sheep, and cleft palate in pigs, when eaten in specific periods of pregnancy. All parts of poison hemlock are toxic. Water hemlock is described as the most violently toxic plant known, with cicutoxin causing convulsions. Not applicable Methods, limits and funding Outcomes: Signs, toxins, birth defects Limitations: 1988 review of livestock; not human data. Read: abstract
Schep 2009 Nicotinic plant poisoning. Clin Toxicol (Phila) · PMID 19778187 · DOI	Systematic search review review	Review of plants with nicotine-like alkaloids	Conium maculatum and other nicotinic plants Not specified Not given here Not given here · vs Not applicable	Coniine and relatives act on nicotinic receptors. Poisoning is biphasic: early stimulation (belly pain, high blood pressure, fast pulse, tremor) then a delayed inhibitory phase (low blood pressure, slow pulse, shortness of breath, coma, respiratory failure). These alkaloids cross the placenta and enter breast milk (stated for the group). Supportive care is the mainstay and outcomes are good with prompt care. Not applicable Methods, limits and funding Outcomes: Mechanism, clinical features, management Limitations: Group-level review; some statements cover nicotine-type plants as a class, not hemlock alone. Read: abstract
Schep 2009 Poisoning due to water hemlock. Clin Toxicol (Phila) · PMID 19514873 · DOI	Narrative review review	Review of water hemlock poisoning (Cicuta and Oenanthe)	Water hemlock (not poison hemlock) Not specified Not given here Not given here · vs Not applicable	Water hemlock (Cicuta and Oenanthe species) is among the most poisonous plants in North America and the UK. Its toxins cicutoxin and oenanthotoxin block GABA in the brain and cause seizures; even a small amount can cause severe poisoning. It is a different plant from poison hemlock. Not applicable Methods, limits and funding Outcomes: Toxins, features, management Limitations: About a different plant; included to separate the two. Read: abstract
Ucar 2026 Divergent clinical outcomes after shared poison hemlock ingestion: evidence suggesting a dose-related effect. Int J Emerg Med · PMID 41922968 · DOI	Case report	2 Two patients who ate the same meal of wild greens later identified as poison hemlock	Wild greens containing poison hemlock Plant material (part not stated in abstract) Not given here Not given here · vs Not applicable	One patient developed early breathing-muscle weakness and progressive ventilatory failure and needed a breathing tube and intensive care. The other had only mild, self-limited symptoms. The author suggests the amount eaten explains the difference. Not applicable Methods, limits and funding Outcomes: Breathing muscle involvement, intensive care need Limitations: Two cases; the amount eaten was not measured, so a dose link is only a suggestion. Funding and conflicts: No competing interests declared. Read: abstract
Vetter 2004 Poison hemlock (Conium maculatum L.). Food Chem Toxicol · PMID 15234067 · DOI	Narrative review review	Review of chemistry, animal and human poisonings	Poison hemlock All vegetative parts, flowers and fruits Not given here Not given here · vs Not applicable	Calls Conium maculatum one of the most poisonous higher plants. Lists the alkaloids (coniine, N-methylconiine, conhydrine, pseudoconhydrine, gamma-coniceine). All vegetative parts, flowers and fruits contain alkaloids and amounts vary with plant variety, conditions and age. Symptoms include stimulation then paralysis of motor nerve endings, vomiting, trembling, slow then fast pulse, convulsions, coma and death. Not applicable Methods, limits and funding Outcomes: Alkaloids and symptoms Limitations: Narrative review from 2004; human data are mostly case reports. Read: abstract
s-gbif GBIF Backbone Taxonomy: Conium maculatum L. (usageKey 3034807) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-mdpoison Poison hemlock, Maryland Poison Center blog · Source	Poison centre page n/a			Methods, limits and funding Read: summary-only
s-pubchem PubChem compound records: coniine, gamma-coniceine, N-methylconiine · Source	Reference database n/a			Methods, limits and funding Read: full-text
Şahin 2026 Conium Maculatum, one plant, four presentations: A case series. Am J Emerg Med · PMID 41643253 · DOI	Case series	4 Four patients poisoned by poison hemlock, Turkey	Poison hemlock plant Plant material (part not stated in abstract) Not given here Not given here · vs Not applicable	Four patients showed very different pictures, from breathing depression to heart-rhythm problems. Some had unique features, including cardiac arrest and a red skin rash. Early recognition and immediate supportive care shaped outcomes. The paper notes the plant resembles parsley and wild carrot. Not applicable Methods, limits and funding Outcomes: Presentation and outcome Limitations: Four cases. Abstract does not list each outcome. Funding and conflicts: No competing interests declared. Read: abstract

What we do not know yet

No clinical trial of hemlock for any use.
No safe preparation or approved use found.
Regulator documents were not read.
Historical medicinal claims are not verified.

How new research is added

New studies are found by a saved PubMed search and placed in a review queue. A person reads each one before it changes any rating or safety statement.

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 5

One of the most dangerous plants; no safe medicinal use. Poison hemlock is described as one of the most poisonous higher plants. All parts contain poison, including the seeds and root. A review says all vegetative parts, flowers and fruits contain alkaloids. We found no safe or approved medicinal use. Do not eat, drink, smoke, juice or apply it. Case report ^{13 8 9}
Poisonings come from mistaking it for food plants. Case reports describe people poisoned after mistaking hemlock for celery, parsnip, parsley or wild carrot. Never forage wild plants of the carrot family unless an expert identifies them in person. A look-alike checklist is not safe enough. Case report ^{8 17 15}
Paralysis and breathing failure. Poisoning is biphasic: early nicotine-like over-stimulation, then weakness and paralysis. Death comes from respiratory arrest and circulatory collapse. In a shared meal, one person needed a breathing tube and intensive care while the other had mild symptoms. Case report ^{10 12 8}
Call for help at once. In the US call Poison Control on 1-800-222-1222 or emergency services. Outside the US, call your local emergency number or poison centre. Do not wait for symptoms to build. Treatment is supportive hospital care, because no antidote exists. Expert review ^{10 5 7}
Do not confuse it with other 'hemlocks'. Water hemlock (Cicuta) and the related hemlock water-dropwort (Oenanthe) are different plants with a different poison (cicutoxin, oenanthotoxin) that causes seizures; water hemlock is described as the most violently toxic plant known to livestock researchers. The hemlock tree (Tsuga) is an unrelated conifer; that statement is general botanical knowledge and was not checked in a source here. Expert review ^{11 9}

Side effects 5

Effect	How often	Severity and recovery	Evidence
Early phase: nausea, vomiting, belly pain, tremor, fast heart rate, high blood pressure Described for nicotine-like plant poisoning in general and for hemlock.	Not established	Moderate to severe Resolves if the person survives	Case report ^{10 13 5}
Muscle paralysis and respiratory failure Death is from respiratory arrest. Survival is high when treated promptly.	Not established	Life-threatening Recovery usually takes a few days with prompt breathing support	Case report ^{10 12 8 5}
Slow or abnormal heart rate, low blood pressure, cardiac arrest Cardiac arrest was a unique feature in one case series.	Not established	Life-threatening Not reported	Case report ^{17 10}
Muscle breakdown (rhabdomyolysis) and acute kidney failure Listed in a literature review.	Not established	Severe Not reported	Case report ⁵
Red skin rash Seen in one case series; skin contact advice is in the poison-centre page named in our summary.	Not established	Mild to moderate Not reported	Case report ¹⁷

Liver

Hemlock is not a known cause of drug-style liver injury, but we did not look for it: LiverTox was not checked. The documented organ harms are nerve, muscle, heart and breathing failure, plus muscle breakdown and kidney failure in some reports. ⁵

How often. No data.

Monitoring. Hospital teams monitor breathing, heart and kidney function in poisoning. This is clinical care, not self-care.

This is a safety connection. It is not evidence that Hemlock supports liver health.

Medicines and supplements 3

With	Why it matters	Importance	Evidence	What to do
Any medicine, supplement or herb general	No interaction study was found. Because hemlock must not be used at all, the question is mainly theoretical.	Not relevant if hemlock is avoided.	Insufficient Not enough evidence ¹⁰	Do not use. Ask your doctor or pharmacist if you have been exposed.
Nicotine-like drugs (for example varenicline) pharmacology	Both act at nicotinic receptors. In goats given poison hemlock, varenicline made signs worse.	Animal data only; not a treatment.	Animal research Very low certainty ³	Do not self-treat poisoning. Call Poison Control or emergency services.
Sedatives and other drugs that depress breathing or the nervous system theoretical	Could add to nerve and breathing depression. Reasoned from the mechanism only; no study.	Unknown.	Pharmacological theory Not enough evidence ¹⁰	Avoid hemlock entirely.

Who should check first 4

Situation	Advice	Evidence
Everyone: any use by mouth, smoking, juicing or on the skin	Avoid. No safe medicinal use was found.	Expert review ^{13 8}
Pregnancy	Avoid any exposure. In livestock, eating hemlock at certain stages of pregnancy causes cleft palate and contracted joints in the young. Whether it harms human pregnancy is not established, but the alkaloid group crosses the placenta.	Animal research ^{2 7 9 10}
Breastfeeding	Avoid. Nicotine-like alkaloids are described as entering breast milk, and hemlock alkaloids have been found in livestock milk. LactMed was not checked.	Expert review ^{10 7}
Children and pets	Keep children and animals away from the plant. We did not verify a child death in the sources read; the risk is that any small body can be poisoned by a small amount. Do not let children handle or taste it.	Expert review ¹³

Overdose, product quality and regulators

Summary. Poison hemlock is among the most poisonous plants known. Severity seems to rise with the amount eaten.

Animal. Livestock show weakness, trembling, early stimulation then depression, and death by respiratory paralysis. Young born to mothers poisoned in specific periods of pregnancy have cleft palate or contracted joints. Animals may return to eat the plant. Mouse lethal doses: coniine 5.5 mg/kg and gamma-coniceine 3.7 to 4.4 mg/kg in different studies.

Human doses studied. None. No dose is given or recommended.

High dose or long term signals. Severity differed between two people sharing a meal, which the author linked to the amount eaten.

Overdose response. Call Poison Control (US 1-800-222-1222) or emergency services immediately. Hospital care is supportive, with breathing support first. No antidote exists.

Genotoxicity. Not covered in the sources read.

Toxic plant parts. All parts, including leaves, stems, flowers, seeds and root. Coniine predominates in the mature plant and seed; gamma-coniceine in early growth.

The risk is mix-ups, not product quality. Hemlock leaves and roots have been mistaken for food plants, and wild greens meals have caused poisonings.

Mistaken for edible plants. Case reports name celery, parsnip, parsley and wild carrot as plants it was confused with. ^{8 17}

Alkaloids in food from animals. A review reports alkaloids can pass into milk and poultry meat from poisoned animals. ⁷

Body	Action	Date

When to get medical help

Call Poison Control (US 1-800-222-1222) or emergency services right away after any eating, drinking or smoke exposure to a possible hemlock plant, even if you feel fine.
Weakness, trembling, trouble breathing, vomiting, fast or slow heartbeat, collapse, or confusion after eating wild greens or roots.

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

Is hemlock safe to use as a herb?

No. We found no safe or approved medicinal use. It is one of the most poisonous plants, and every part, including the seeds and root, contains poison.

^{13 8}

What does hemlock poisoning feel like?

First a nicotine-like phase with belly pain, vomiting, tremor and a fast heart. Then weakness and paralysis that can stop breathing. Call Poison Control (US 1-800-222-1222) or emergency services at once.

^{10 12}

Can hemlock kill?

Yes. Death comes from respiratory arrest and circulatory collapse. With prompt hospital support many people recover within days.

^{8 5}

How do people get poisoned?

Mostly by mistaking it for edible plants such as celery, parsnip, parsley or wild carrot. Never forage wild carrot-family plants unless an expert identifies them in person.

^{8 17}

Is there an antidote?

No specific antidote is known. Care is supportive, with breathing help first. A drug tested in goats made things worse.

^{7 3}

Did hemlock kill Socrates?

A 2024 analysis judges it a likely case of poison hemlock poisoning. It is a historical reading, not a clinical study.

Is it the same as water hemlock?

No. Water hemlock (Cicuta) and hemlock water-dropwort (Oenanthe) are different plants whose toxins cause seizures. Both can be deadly. The hemlock tree is an unrelated conifer.

^{11 9}

Is it dangerous for pets and livestock?

Yes. Livestock get weakness, trembling and death from respiratory paralysis. Eaten in pregnancy, it caused cleft palate and joint deformities in young animals.

^{9 7 2}

Is hemlock safe in pregnancy or breastfeeding?

Avoid any exposure. Birth defects occurred in livestock, and nicotine-like alkaloids pass the placenta and breast milk. Effects in human pregnancy are not established.

^{2 10}

Can it interact with medicines?

No study exists. Because hemlock must be avoided entirely, ask a doctor or pharmacist if you have been exposed.

¹⁰

What should I do after touching or smoking it?

Call Poison Control for advice. A poison-centre page cited in our summary advises rinsing skin with lukewarm water and leaving the area if smoke was breathed in.

¹⁵

Has any regulator approved it?

We did not read any regulator document, so we cannot say. We found no approved medicinal use.

¹³

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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 read our existing herb summary, searched PubMed, read the abstract of each PubMed record cited, and checked the plant name in GBIF and compounds in PubChem.
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.

Sources 17

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

Dayan AD. Death of Socrates: a likely case of poison hemlock (Conium maculatum) poisoning.. Clin Toxicol (Phila). 2024. PMID 38348840. DOI 10.1080/15563650.2024.2309328. (abstract)
Green BT, Lee ST, Panter KE, Brown DR. Piperidine alkaloids: human and food animal teratogens.. Food Chem Toxicol. 2012. PMID 22449544. DOI 10.1016/j.fct.2012.03.049. (abstract)
Green BT, Lee ST, Welch KD, Cook D, Stonecipher CA. The actions of varenicline on alkaloids from Conium maculatum (poison hemlock), Lupinus sulphureus (sulphur lupine) and Nicotiana glauca (tree tobacco).. Toxicon. 2024. PMID 39577702. DOI 10.1016/j.toxicon.2024.108184. (abstract)
Hotti H, Rischer H. The killer of Socrates: Coniine and Related Alkaloids in the Plant Kingdom.. Molecules. 2017. PMID 29135964. DOI 10.3390/molecules22111962. (abstract)
Karakasi MV, Tologkos S, Papadatou V, Raikos N, Lambropoulou M, Pavlidis P. Conium maculatum intoxication: Literature review and case report on hemlock poisoning.. Forensic Sci Rev. 2019. PMID 30594904. (abstract)
Lee ST, Green BT, Welch KD, Jordan GT, Zhang Q, Panter KE, et al.. Stereoselective potencies and relative toxicities of γ-coniceine and N-methylconiine enantiomers.. Chem Res Toxicol. 2013. PMID 23514442. DOI 10.1021/tx400050r. (abstract)
López TA, Cid MS, Bianchini ML. Biochemistry of hemlock (Conium maculatum L.) alkaloids and their acute and chronic toxicity in livestock. A review.. Toxicon. 1999. PMID 10340826. DOI 10.1016/s0041-0101(98)00204-9. (abstract)
Nunes J, Pina S, Oliveira AC, Moreno J, Pérez P. Acute Intoxication With Poison Hemlock (Conium maculatum).. Cureus. 2025. PMID 40248547. DOI 10.7759/cureus.80763. (abstract)
Panter KE, Keeler RF, Baker DC. Toxicoses in livestock from the hemlocks (Conium and Cicuta spp.).. J Anim Sci. 1988. PMID 3049497. DOI 10.2527/jas1988.6692407x. (abstract)
Schep LJ, Slaughter RJ, Beasley DM. Nicotinic plant poisoning.. Clin Toxicol (Phila). 2009. PMID 19778187. DOI 10.1080/15563650903252186. (abstract)
Schep LJ, Slaughter RJ, Becket G, Beasley DM. Poisoning due to water hemlock.. Clin Toxicol (Phila). 2009. PMID 19514873. DOI 10.1080/15563650902904332. (abstract)
Ucar AB. Divergent clinical outcomes after shared poison hemlock ingestion: evidence suggesting a dose-related effect.. Int J Emerg Med. 2026. PMID 41922968. DOI 10.1186/s12245-026-01159-4. (abstract)
Vetter J. Poison hemlock (Conium maculatum L.).. Food Chem Toxicol. 2004. PMID 15234067. DOI 10.1016/j.fct.2004.04.009. (abstract)
. GBIF Backbone Taxonomy: Conium maculatum L. (usageKey 3034807). . . (full-text)
. Poison hemlock, Maryland Poison Center blog. . . (summary-only)
. PubChem compound records: coniine, gamma-coniceine, N-methylconiine. . . (full-text)
Şahin EA, Seida I, Balcioglu ZB. Conium Maculatum, one plant, four presentations: A case series.. Am J Emerg Med. 2026. PMID 41643253. DOI 10.1016/j.ajem.2026.01.037. (abstract)

Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.