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Ingredients

Neem

Azadirachta indica

Snapshot

IndicationsContraindications
  • Plaque and gingivitis1
  • Root canal irrigation2
  • Glycemia in metabolic syndrome3
  • Head lice3
  • Oral neem oil ingestion3
  • Hypoglycemic medications or herbs4
  • Pregnancy or nursing5

Neem (Azadirachta indica) is a South Asian tree whose bark, leaves, flowers, and seeds are used in Ayurvedic medicine, externally for skin conditions, internally for gastrointestinal complaints, and for oral hygiene3. Its antimicrobial activity drives most supplementation, and anti-ulcer effects are attributed to proton pump inhibition3. Uses that follow are plaque and gingivitis control, skin care, and glycemic support in metabolic syndrome3.

Systematic reviews of herbal mouthrinses report reduced plaque and gingival inflammation versus placebo, with neem among products that outperformed chlorhexidine, though unclear risk of bias limits conclusions1. As a root canal irrigant, neem showed antimicrobial efficacy similar to sodium hypochlorite and less post-operative pain, yet natural irrigants cannot replace it routinely. In human cervical cancer cell lines, a 2022 laboratory study found neem stem bark extract induced cell cycle arrest and apoptosis; no human trial has tested it. Products listing neem number 251, mostly capsules and tablets plus powders and teas; see Form comparison.

The most consequential caution is toxicity: swallowed neem oil has caused seizures, coma, and death3. Health Canada lists a caution against combining it with hypoglycemic medications or herbs4.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

62 sources, 52 studies

  • When to useThe situations practitioners use it for, each with the reason and the study behind it.
  • SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
  • InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
  • Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
  • How it worksWhat it is and how it works in the body, in plain terms.
  • Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
  • Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
  • Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.
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Sources

  1. 1Effect of herbal mouthrinses on dental plaque formation and gingival inflammation: A systematic review.pubmed.ncbi.nlm.nih.govSanti, Casarin, Grellmann et al. · Oral diseases · 2021 · Pubmed
  2. 2Can natural irrigants replace sodium hypochlorite? A systematic review.pubmed.ncbi.nlm.nih.govSusila, Sai, Sharma et al. · Clinical oral investigations · 2023 · Pubmed
  3. 3MSKCCmskcc.orgMemorial Sloan Kettering — About Herbs, Botanicals & Other Products
  4. 4Health Canadahealth-products.canada.caLabel statements and adult daily amounts Health Canada authorized on licensed natural health products with this ingredient alone, from the Licensed Natural Health Products Database. Contains information licensed under the Open Government Licence – Canada
  5. 5US product labelsdsld.od.nih.govWarnings printed on US dietary supplement labels with this ingredient, from the NIH Office of Dietary Supplements' Dietary Supplement Label Database (DSLD). Manufacturers' precautions, not evidence of harm