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Ayurveda

NeemAzadirachta indica

A bitter Ayurvedic tree used for worms and the liver; a bark-extract study cut gastric acid secretion by 77% in 10 days but describes no placebo group.

Botanical name
Azadirachta indica
Part used
bark, leaf (seed oil is a separate, toxic product)
Also called
Sanskrit Nimba, Prabhadra, Arishta; Hindi Neem, Nim, Nimb; Indian lilac, Margosa
Used in
Ayurveda
Taken for
Antimicrobial use, Reflux and heartburn, The gut lining
Sold as
bark powder (churna), leaf powder, capsules, tablets, decoction, aqueous extract

What is meant by neem

Neem is a fast-growing evergreen tree of the mahogany family, native to India and common across South Asia. Almost every part is used: the bark, the leaves, the flowers, the fruit and the seed oil. The bark and the leaf are the usual gut remedies, while the seed oil (neem or margosa oil) is a separate preparation that has caused poisonings and is not taken as a digestive herb.

In Ayurveda the plant is called nimba and is the classic bitter. Gut products are made from the dried bark or leaf as a powder (churna), a decoction, a capsule or tablet, or an aqueous extract. Neem is also an ingredient in some antiparasitic formulas alongside black walnut, wormwood and clove, which is how many people meet it on a label. Its gastric reputation rests on a set of animal studies and one human report on the bark extract from a single research group. This entry says what those studies did and did not test.

In the traditions

Ayurveda (about Ayurveda)

An Ayurvedic college monograph lists nimba’s taste as bitter and astringent, its qualities as light and dry, its potency as cooling and its post-digestive effect (vipaka) as pungent. Its action on the doshas is given as calming kapha and pitta, and its other listed actions include dipana (kindling digestion), grahi (binding) and krimighna (worm-destroying). The Charaka Samhita is cited for placing it among the bitter-taste group of herbs. For the gut the monograph lists a bark decoction with honey for intestinal worms, jaundice, loss of appetite, vomiting, dysentery and liver disease, describes the leaves as a liver stimulant and the fruit as purgative. These are the tradition’s claims about the plant, not trial results.

What the plant contains

Neem contains triterpenoids called limonoids, including azadirachtin. A review of its anti-ulcer work reports that the bark extract reduced acid secretion in animals and compared it with ranitidine and omeprazole in some animal models. Reviews also list anti-parasitic, anti-inflammatory, anti-ulcer, hepatoprotective and blood-sugar-lowering effects in animal work. These are lab and animal findings, and they are why the research group moved to a human study.

What has been tested in people

The only human study we found of neem for the gut is a 2004 report on aqueous bark extract in people with acid-related problems and gastroduodenal ulcers. The abstract describes treated patients, mentions no placebo group and gives no number of participants. The reported results:

A 2009 review of the same group’s work reviews the animal and mechanism studies and clinical studies where available. We could not find a randomized, placebo-controlled trial of neem for ulcers, reflux, parasites or any other gut outcome, a trial in Helicobacter pylori, or any trial of the leaf for the gut. The traditional worm use has no human trial in the sources we read.

StudyDoseWhat it found
Clinical studies of neem bark aqueous extract in patients with acid-related problems and gastroduodenal ulcers (no placebo group described; number not stated in the abstract) PMID 1545433930 mg twice a day for 10 days; 30 to 60 mg twice a day for 10 weeks (duodenal ulcer); 30 mg twice a day for 6 weeks (esophageal and gastric ulcer)Gastric acid secretion down 77% (P < 0.002); secretion volume down 63%, pepsin down 50%; duodenal ulcers almost completely healed at 10 weeks; one esophageal and one gastric ulcer healed at 6 weeks
Review of neem for gastric hyperacidity and ulcer PMID 19140119VariousSummarizes antisecretory and gastroprotective work, animal comparisons with ranitidine and omeprazole, and clinical studies where available
Review of the toxicology of neem preparations (human and animal oral data) PMID 15261960VariousNon-aqueous extracts appeared most toxic; reversible effects on reproduction were the main toxic effect with repeated exposure

Doses used in trials and traditional preparations

The 2004 study used a freeze-dried aqueous bark extract at 30 mg twice a day for 10 days (acid secretion), 30 to 60 mg twice a day for 10 weeks (duodenal ulcers) and 30 mg twice a day for 6 weeks (one esophageal and one gastric ulcer). The study dosed a freeze-dried extract, so these milligram amounts are not comparable with a bark powder or decoction. Traditionally the bark or leaf is taken as a decoction or powder, and the monograph names a bark decoction with honey for worms. We found no dose-response study.

Treat these figures as a record of what was studied. Whether any amount of neem suits a particular person is a question for a clinician or pharmacist who knows their history.

Safety

In the 2004 study, blood markers of organ function stayed near control values on the doses above. Whole-plant safety is a different matter from the seed oil. Case reports document neem oil poisoning in children, for example a 5-year-old with refractory seizures and metabolic acidosis who was left with hearing and vision disturbances and ataxia, and margosa oil has been reported to cause toxic encephalopathy. A review of the toxicology data found non-aqueous extracts the most toxic of the neem preparations and reversible effects on reproduction in male and female mammals the main toxic effect with sub-acute or chronic exposure. We found no pregnancy or breastfeeding safety studies for the bark.

On contamination, a 2008 study of 193 Ayurvedic products sold online found lead, mercury or arsenic in 20.7%, a figure that reached 40.6% in products made with metals (rasa shastra). The study did not test neem by name.

Drug interactions

We found no human interaction studies for neem. The toxicology review lists blood-sugar-lowering among its beneficial effects in animals, which raises a question of added effect with diabetes medicines; this was not tested in people in the sources we read. Neem’s effect on stomach acid output is a documented one in the 2004 study, so it plausibly overlaps with acid-suppressing medicines and with antacids that depend on stomach acidity. That is a mechanism, not a documented interaction.

Prescriptions flagged alongside neem

Published interaction references put these medicines next to this herb, and the quiz acts on them; a pharmacist is the person to confirm any of it:

Products in the catalog with neem

These catalog entries list neem or one of its preparations among their active ingredients. Each page shows the amount on the label, the trials behind it and what buyers report.

Renew Life PARA SMART Cleansing Formula, 15-Day Program 4.2 out of 5 from 1,398 ratings from Amazon · ~$2.04 a day across the full 15-day program

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Related herbs

Ayurvedic Guduchi Tinospora cordifolia Ayurvedic Kutki Picrorhiza kurroa Western Wormwood Artemisia absinthium Western Black walnut Juglans nigra

Questions people ask

What is neem used for in digestion?

Ayurveda lists a bark decoction with honey for intestinal worms, jaundice, loss of appetite, vomiting and dysentery, and the monograph calls it digestion-kindling and worm-destroying. The only human gut data we found is a 2004 study of a bark extract on stomach acid and ulcers.

Did neem heal ulcers in people?

In the 2004 study, a 10-week course of 30 to 60 mg twice a day almost completely healed duodenal ulcers on X-ray or endoscopy, and gastric acid secretion fell 77% at 10 days. The abstract describes no placebo group and gives no number of patients, so the size of the effect against placebo is unknown.

Is neem oil safe to swallow?

Case reports describe neem oil poisoning in children, including seizures and metabolic acidosis in a 5-year-old. The gut studies used a bark extract, which is a different preparation.

Is neem the same as margosa?

Yes, margosa is another English name for the neem tree. Margosa oil poisoning refers to the seed oil.

Does neem affect fertility?

A toxicology review reported reversible effects on reproduction in male and female mammals as the main toxic effect with repeated neem exposure. We found no human data on neem bark and fertility.

Sources