Neem (Azadirachta indica): Uses, Evidence and Safety
Neem (Azadirachta indica): why swallowing neem oil has caused severe poisoning in children and adults, what research shows for mouth rinses and skin, and Ayurvedic background.
Content last updated . This page has not been medically reviewed.
Safety first. Natural products can cause side effects and interact with medicines. Read herb safety and interactions before you use anything on this page.
What is Neem good for?
What the body uses it for, and how strong the evidence is. A normal job in the body is not proof that extra supplements add benefit; each card says which.
Mouth rinse for plaque and gum inflammation
Preliminary or mixedA systematic review of 3 randomized trials found neem mouth rinse about as effective as chlorhexidine rinse alongside toothbrushing in people with gingivitis. The authors called the evidence flawed and the risk of bias unclear.
Supplements: Promising but limited; MSK calls the data conflicting. Results apply to rinses, not to capsules or oil.
Head lice (shampoo)
Preliminary or mixedMSK's summary says neem is effective against head lice, citing a shampoo study in naturally infected people. We did not read that study.
Supplements: Based on one cited study that we did not read; downgraded accordingly.
Skin conditions (traditional use)
Not enough evidenceIn Ayurvedic medicine neem is used on the skin for skin conditions. We found no controlled human trial in the sources we read.
Supplements: No good evidence of benefit from the sources read.
Stomach acid and ulcers
Not enough evidenceMSK reports a small human study in which bark extract reduced stomach acid secretion; more human studies are needed.
Supplements: One small study; not enough to support use.
HIV (CD4 counts)
Not enough evidenceMSK reports higher CD4 counts in a small number of volunteers with HIV; the evidence is limited and more studies are needed.
Supplements: Not a substitute for HIV treatment; evidence is too limited.
Cancer-cell growth in the lab
Lab or animal research onlyLab and animal studies suggest neem extracts can slow cancer-cell growth. MSK says no human data support neem as a cancer treatment.
Supplements: No human evidence of benefit.
Contraceptive and antifertility activity (animal and lab studies)
Lab or animal research onlyA 2021 review of 27 studies examined antifertility, antiovulation and abortifacient activity of neem. The abstract we read gives no conclusion on safety or effect in people.
Supplements: Not an established contraceptive; do not rely on it. Ask a clinician about pregnancy or trying to conceive.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Body systems (1)
- Nervous SystemDocumented risk
Swallowing neem oil has caused seizures, coma and brain damage in case reports; this is a documented harm, not a benefit.
Body parts (2)
- BrainDocumented risk
Swallowing neem oil has caused seizures, coma and brain damage in case reports; this is a documented harm, not a benefit.
- SkinDocumented risk
Allergic contact dermatitis has been reported with neem oil on the skin. Traditional skin use has no controlled trial support in the sources read.
Root causes (1)
- Medication Side EffectsDocumented risk
A neem extract inhibited several liver drug-clearing enzymes in the lab; clinical relevance is unknown, so ask a pharmacist if you take medicines.
Conditions & symptoms (1)
- Drug ToxicityDocumented risk
Swallowing neem oil has caused severe poisoning with seizures, coma and death in case reports.
Documented risks and interactions (5)
- Safety: neem oil swallowed has caused severe poisoning. MSK reports that swallowing neem oil has caused severe poisoning in children and adults, with vomiting, drowsiness, seizures, coma and, in the worst cases, death. Neem oil should not be swallowed.
- Safety: brain effects in children after neem oil. A case report describes a previously healthy 5-year-old with seizures that did not respond to treatment and metabolic acidosis after neem oil poisoning, with later hearing, vision and coordination problems.
- Possible medicine interactions (liver enzymes). In laboratory work, a neem extract inhibited the liver enzymes CYP3A4/5, CYP2C8 and CYP2C9. MSK says the clinical relevance is unknown.
- Skin reactions. Allergic contact dermatitis has been reported, including acute scalp and face dermatitis after neem oil for hair loss.
- Toxicity data are limited. A 2021 review notes that the safety of neem compounds is not always considered and few in vivo toxicity studies have been done.
Safety first: do not give neem oil by mouth, to a child or an adult. Memorial Sloan Kettering Cancer Center (MSK, US) says swallowing neem oil has caused severe poisoning in both children and adults, and that in the most serious cases seizures with coma, and even death, have occurred. [1] Reported effects include vomiting, drowsiness, diarrhea, vision loss, seizures and brain damage. [1] A case report describes a previously healthy 5-year-old with refractory seizures and metabolic acidosis after neem oil poisoning, with later hearing, vision and coordination problems. [2] If someone has swallowed neem oil or any neem product, call Poison Help in the US at 1-800-222-1222, or 911 if they have seizures, are very drowsy or cannot be woken. See poisoning: what to do first and poison help by country.
What neem is
Neem is Azadirachta indica A.Juss., a tree in the family Meliaceae. [3] MSK describes it as a tree common in South Asia whose bark, leaves, flowers and seeds have been used as food and medicine. [1] Neem is also used against pests and parasites, so pesticide and garden products also carry the name. [1] They are not health products and are not covered here. Neem oil (pressed from seeds) is a different product from a leaf extract, a bark extract, a mouth rinse or a gel. Results and risks for one do not transfer to another.Traditional use
This is tradition, not proof. MSK says that in Ayurvedic medicine neem is used on the skin for skin conditions, by mouth for stomach ailments and for oral hygiene. [1] For the tradition in its own terms, see Neem (Nimba) in Ayurveda and Ayurveda.What research shows
| Use and form | What the source found | Strength of evidence | Who or what was studied |
|---|---|---|---|
| Plaque and gum inflammation (neem mouth rinse) | A systematic review of 3 randomized trials found neem rinse about as effective as chlorhexidine rinse as an add-on to brushing. The authors called the evidence flawed, with unclear risk of bias. [4] | Promising but limited | People with gingivitis; mouth rinse |
| Head lice (seed-extract shampoo) | MSK's summary says neem is effective against lice, based on one cited study. [1] We did not read that study. | Promising but limited | Shampoo; one study cited |
| Stomach acid and ulcers (bark extract) | MSK reports a small study in which bark extract reduced stomach acid secretion; more studies in humans are needed. [1] | Insufficient evidence | Small human study; oral extract |
| HIV (leaf extract) | MSK reports higher CD4 counts in a small number of volunteers; more studies are needed. [1] | Insufficient evidence | Small human study |
| Cancer | MSK says lab studies suggest neem extracts can inhibit cancer-cell growth, but there are no human studies showing it to be an effective cancer treatment. [1] | Preclinical (cells or animals) | Cell and animal studies |
| Skin conditions such as eczema or acne | Used traditionally. [1] Proper evidence not found in the sources we read (MSK summary, PubMed reviews) for a controlled human trial. | Traditional use only | Not applicable |
| Contraception or fertility | A 2021 review examined 27 studies on antifertility, antiovulation and abortifacient activities of neem. [5] The abstract we read gives no human safety conclusion. | Insufficient evidence | Review of mixed studies |
Forms and why the form matters
A mouth rinse used in a trial, a seed oil swallowed by a child and a leaf extract in a capsule are three different exposures. A 2021 review of neem toxicity notes that the safety of neem compounds is not always taken into consideration and that few in vivo toxicity studies have been performed. [6]Safety
- Medicines: in laboratory work, a neem extract inhibited the liver enzymes CYP 3A4/5, 2C8 and 2C9; clinical relevance is not known. [1] Many medicines are cleared by these enzymes, so ask a pharmacist; see how interactions work.
- Skin: allergic contact dermatitis has been reported, as has acute contact dermatitis on the scalp and face after neem oil for hair loss. [1] MSK lists rash and itchy, dry or reddened skin as topical effects. [1]
- Pregnancy, trying to conceive and breastfeeding: the MSK page does not give guidance, and a review has examined neem for antifertility and abortifacient activity. [5] Treat neem as something to ask a clinician about; see pregnancy and breastfeeding.
- Infants and children: neem oil poisoning with brain effects has been reported in an infant and in a 5-year-old. [7][2] See a child swallowed a natural product.
- Liver, kidney, older adults, surgery, bleeding: not described in the sources we read, so safety is unknown, not proven. Tell the surgical team about any neem product.
- Quality: product content varies; see quality testing and certifications and adulterated Ayurvedic products.
Related pages
Turmeric, herbs for skin, acne, eczema and wounds, and tea tree oil.Frequently asked questions
Is neem oil safe to swallow?
No. MSK says swallowing neem oil has caused severe poisoning in children and adults. Call Poison Help in the US at 1-800-222-1222 if it has happened. [1]
Does neem work for skin problems?
It is used traditionally for skin conditions, but we found no controlled human trial in the sources we read. Proper evidence not found. [1]
Does a neem mouth rinse work for gums?
A systematic review of 3 trials found it about as effective as chlorhexidine rinse as an add-on to brushing, but the evidence was flawed. [4]
Can neem be used in pregnancy?
The MSK page gives no guidance, and neem has been studied for antifertility activity. Ask a clinician before using any neem product. [1][5]
Does neem interact with medicines?
A neem extract inhibited several liver enzymes in laboratory work, with unknown clinical relevance. Ask a pharmacist if you take prescription medicines. [1]
References
- Memorial Sloan Kettering Cancer Center, About Herbs: Neem. Read 2026-10-23.
- Dhongade RK et al., Neem oil poisoning. Indian Pediatr 2008 (PubMed 18250509). Read 2026-10-23.
- GBIF Backbone Taxonomy, Azadirachta indica match record. Read 2026-10-23.
- Dhingra K, Vandana KL, Effectiveness of Azadirachta indica (neem) mouthrinse in plaque and gingivitis control: a systematic review. Int J Dent Hyg 2017 (PubMed 26876277). Read 2026-10-23.
- Patil SM et al., Azadirachta indica A. Juss (neem) as a contraceptive: an evidence-based review. Phytomedicine 2021 (PubMed 34092456). Read 2026-10-23.
- Braga TM et al., Azadirachta indica A. Juss. In Vivo Toxicity-An Updated Review. Molecules 2021 (PubMed 33419112). Read 2026-10-23.
- Kumar S, Kumar N, Neem oil poisoning as a cause of toxic encephalopathy in an infant. Indian J Pediatr 2014 (PubMed 24522945). Read 2026-10-23.