Health Care Professional Information

Scientific Name
Azadirachta indica
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Clinical Summary

Azadirachta indica or neem is a tree prevalent in South Asia. The bark, leaves, flowers, and seeds of which have been utilized as food and medicine for centuries. In Ayurvedic medicine, neem is used externally for skin conditions; and internally for gastrointestinal ailments and for oral hygiene. Currently, many forms of neem extracts are marketed as dietary supplements.
Neem has antimicrobial activity and is used against a wide range of pests and parasites (1). It is effective against lice (2) (3) (4) and has antiretroviral activity (5). Neem also reduces plaque and decreases oral bacterial counts (3), but data are conflicting (4).
A neem bark extract was found to exhibit anti-secretory and anti-ulcer properties (6). Neem may also be effective in the treatment of cholera and diarrhea (7) (8).

A few studies have examined the anticancer potential of neem. An ethanolic extract of neem leaves reduced the incidence of stomach tumors (9), and neem-treated monocytes induced apoptosis in cervical (10) and prostate cancer cells (11). Neem also showed chemopreventive effects in animal models (12). However, human data are lacking.

Neem oil has been reported to cause nausea, drowsiness and tachypnea in children (8).

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Purported Uses
  • Ulcers
  • Cancer Treatment
  • Antiviral
  • Antifungal
  • Oral Hygiene
  • Pesticide
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Constituents
  • Isoprenoids: Protomeliacins, limonoids, azadirone and its derivatives, gedunin and its derivatives, nimbin, salanin and azadirachtin
  • Non-isoprenoids: Amino acids, polysaccharides, sulphurous compounds, flavonoids, dihydrochalcone, coumarin and tannins
    (14)
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Mechanism of Action

The anti-secretory effects of neem are via the inhibition of the proton pump, H+- K+- ATPase, to control the secretion of hydrochloric acid. The anti-ulcer effects are believed to be through inhibition of gastric mucus depletion and prevention of oxidative mucosal damage. Neem also scavenges hydroxyl radicals, which are known to contribute to the formation of gastric lesions (6).
Neem induces cell death in prostate cancer cells by decreasing the levels of Bcl-2, an anti-apoptotic protein. Neem-treated monocytes induce apoptosis in cervical cancer cells by increasing levels of caspases 3, 8, and 9, interferon (IFN-gamma), and by decreasing tumor necrosis factor (TNF-alpha) (10). 
Neem also acts as an antiretroviral agent via inhibition of viral invasion of host cells (5).

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Warnings

Oral administration of neem oil resulted in severe poisoning in children. Vomiting, drowsiness and diarrhea have also been reported. In most serious cases, seizures associated with coma have occurred (8).

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Adverse Reactions

Reported: Vomiting, drowsiness, diarrhea, tachypnea with acidotic respiration, polymorphonuclear leukocytosis, encephalopathy, and seizures associated with coma have been reported following oral administration of neem (8).

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Herb-Drug Interactions

Some studies show that neem extracts have antioxidant activities. Theoretically, antioxidants can decrease the efficacy of certain chemotherapy drugs that rely on the generation of free radicals for their cytotoxic effects. Supplements with antioxidant properties are not recommended during chemotherapy.

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Literature Summary and Critique

Udeinya IJ, Mbah AU, Chijioke CP, Shu EN. An antimalarial extract from neem leaves is antiretroviral. Transactions of the Royal Society of Tropical Medicine and Hygiene. Jul 2004;98(7):435-437.
Ten ambulatory HIV-positve volunteers were included in this study. All received oral gelatin capsules containing neem extract (1000 mg), once daily for 30 days. They were not given any other antiretroviral drugs. Bodyweight, blood cell count, and CD4+ cell count were measured before and after the study period. The increases in body weight and blood cell count after 30 days was significant among all participants. No adverse effects were reported. Larger studies are required to determine the efficacy and long-term effects of neem.

Bandyopadhyay U, Biswas K, Sengupta A, et al. Clinical studies on the effect of Neem (Azadirachta indica) bark extract on gastric secretion and gastroduodenal ulcer. Life sciences. Oct 29 2004;75(24):2867-2878.
Twenty patients, aged 18 — 45 years, were selected on the basis of gastro-acidity symptoms and/or ulcer diagnosis. Capsules (30 mg) containing filtered and lyophilized extract from neem tree bark were orally administered, twice daily, 30 minutes before lunch and dinner, for ten days. For a month before the onset of the treatment, patients received no other drugs. Administration of neem extract resulted in a 63% reduction in volume of gastric secretion, and a 77% inhibition of total acid secretion. Though the results were significant and no adverse effects were recorded,  larger studies must be conducted to fully assess the value of neem as an anti-secretory drug.

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Dosage (Inside MSKCC Only)
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References
  1. Schmahl G, Al-Rasheid KA, Abdel-Ghaffar F, Klimpel S, Mehlhorn H. The efficacy of neem seed extracts (Tre-san, MiteStop on a broad spectrum of pests and parasites. Parasitology research. Jul 2010;107(2):261-269.
  2. Abdel-Ghaffar F, Semmler M. Efficacy of neem seed extract shampoo on head lice of naturally infected humans in Egypt. Parasitology research. Jan 2007;100(2):329-332.
  3. Pai MR, Acharya LD, Udupa N. Evaluation of antiplaque activity of Azadirachta indica leaf extract gel—a 6-week clinical study. Journal of ethnopharmacology. Jan 2004;90(1):99-103.
  4. Sharma S, Saimbi CS, Koirala B, Shukla R. Effect of various mouthwashes on the levels of interleukin-2 and interferon-gamma in chronic gingivitis. The Journal of clinical pediatric dentistry. Winter 2008;32(2):111-114.
  5. Udeinya IJ, Mbah AU, Chijioke CP, Shu EN. An antimalarial extract from neem leaves is antiretroviral. Transactions of the Royal Society of Tropical Medicine and Hygiene. Jul 2004;98(7):435-437. 6.
  6. Bandyopadhyay U, Biswas K, Sengupta A, et al. Clinical studies on the effect of Neem (Azadirachta indica) bark extract on gastric secretion and gastroduodenal ulcer. Life sciences. Oct 29 2004;75(24):2867-2878.
  7. Thakurta P, Bhowmik P, Mukherjee S, et al. Antibacterial, antisecretory and antihemorrhagic activity of Azadirachta indica used to treat cholera and diarrhea in India. Journal of ethnopharmacology. May 22 2007;111(3):607-612.
  8. Krieger R. Human Health Effects. 2001. http://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+7372. Accessed July 27, 2012.
  9. Gangar SC, Koul A. Azadirachta indica modulates carcinogen biotransformation and reduced glutathione at peri-initiation phase of benzo(a)pyrene induced murine forestomach tumorigenesis. Phytotherapy research : PTR. Sep 2008;22(9):1229-1238.
  10. Vasenwala SM, Seth R, Haider N, et al. A study on antioxidant and apoptotic effect of Azadirachta Indica (neem) in cases of cervical cancer. Archives of gynecology and obstetrics. Jun 21 2012.
  11. Kumar S, Suresh PK, Vijayababu MR, Arunkumar A, Arunakaran J. Anticancer effects of ethanolic neem leaf extract on prostate cancer cell line (PC-3). Journal of ethnopharmacology. Apr 21 2006;105(1-2):246-250.
  12. Dasgupta T, Banerjee S, Yadava PK, Rao AR. Chemopreventive potential of Azadirachta indica (Neem) leaf extract in murine carcinogenesis model systems. Journal of ethnopharmacology. May 2004;92(1):23-36.
  13. Mbah AU, Udeinya IJ, Shu EN, et al. Fractionated neem leaf extract is safe and increases CD4+ cell levels in HIV/AIDS patients. American journal of therapeutics. Jul-Aug 2007;14(4):369-374.
  14. Brahmachari G. Neem—an omnipotent plant: a retrospection. Chembiochem. 2004 Apr 2;5(4):408-21.
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Consumer Information

How It Works

Bottom Line: Neem has anticancer effects. More studies are needed to test its effects in humans.

Neem is an herb that is used as food, and in traditional medicine for skin conditions and for stomach ailments. It is also used as a disinfectant against pests and parasites. Some lab studies show that neem extracts have anticancer activities by inhibiting cancer cell growth. However, there are no human studies showing it to be an effective cancer treatment. Adverse reactions caused by neem oil have been reported in children.

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Purported Uses
  • Ulcers
    A small study found neem bark extract effective in reducing stomach acid secretion without any adverse effects. More studies are needed in humans.
  • Cancer
    In vitro studies show neem can inhibit cancer cell growth. It has not been studied as a treatment for cancer.
  • Antiviral
    Neem extract has been shown to increase CD4+ cell count and bodyweight in a small number of HIV+ volunteers.
  • Oral Hygiene
    Neem can reduce oral plaque and bacterial count. It is used as mouth rinse in traditional medicine.
  • Pesticide/fungicide
    Neem oil has been used externally against pests and lice.
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Patient Warnings

Swallowing neem oil can cause severe adverse effects in children.

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Side Effects

Vomiting, drowsiness, diarrhea, and seizures associated with coma have been reported.

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Last updated: August 31, 2012
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