Neem

Common name: Nim, nimmi, vepa, tamarkha, kohomba, margosa tree, Indian lilac

Botanical names: Azadirachta indica, Melia azadirachta

Parts used and where grown

The neem tree, a member of the Meliaceae family, appears to have originated in India and Southeast Asia and been spread throughout drier lowland tropical and subtropical regions of Africa, the Middle East, the Americas, Australia, and South Pacific islands. The leaves, used as medicine, are generally available all the year round as the tree is evergreen except during severe droughts or if exposed to frost.

Neem has been used in connection with the following conditions (refer to the individual health concern for complete information):

Science Ratings	Health Concerns
	Gingivitis (periodontal disease) Peptic ulcer Tooth decay Vaginitis
Reliable and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit. For a herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

Science Ratings

Health Concerns

Gingivitis (periodontal disease)

Peptic ulcer

Tooth decay

Vaginitis

Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars

Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star

For a herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

Historical or traditional use (may or may not be supported by scientific studies)

Neem has a long history of use in the traditional medical systems of India (Ayurvedic, Unani-Tibb).¹ Neem leaf and bark extracts are most consistently recommended in ancient medical texts and by herbal practitioners for gastro-intestinal upsets, diarrhoea and intestinal infections, skin ulcers and infections, and malaria.² Neem twigs are the most regularly used toothbrush for a large portion of the population of India and other countries where the tree is common.³ The effectiveness of many of these uses has been confirmed in modern research studies, showing, for example, that neem bark extracts are effective for people with stomach ulcers, that leaf gel can effectively fight periodontal disease, and that leaf extracts can combat scabies infections.⁴ ⁵ ⁶ The claimed contraceptive effects of neem have been confirmed in some animal studies showing that seed extracts of neem are spermicidal.⁷

Active constituents

The major active constituents in neem are terpenoids such as azadirachtin, which are considered to be antimicrobial and insect repellant among many other actions, and fatty acids and possibly other compounds in neem oil.⁸ ⁹

How much is usually taken?

Traditionally, neem has been administered as roughly 10 to 20 ml (2 to 4 teaspoons) of leaf juice or 2 to 4 grams (1/7 to 1/10 of an ounce) of powdered leaf two or three times per day.¹⁰ Leaf extract gel or toothpaste, 1 gram (1/5 of a teaspoon) in the morning and at bedtime brushed all over the mouth, has been used effectively for dental plaque.¹¹ Freeze-dried neem bark extract (30 to 60 mg twice a day) has been shown helpful for people with stomach ulcers.¹² Creams containing 5% or more of neem oil or neem extracts are typically applied at least twice per day for skin or vaginal infections. Neem oil (in a concentration of 1 to 4%) mixed in coconut, mustard, or other oil bases is used for repelling insects.¹³

Are there any side effects or interactions?

Neem leaf extracts and teas appear to be very safe at recommended intake levels with no significant reports of problems. Neem seed oil is more problematic and should be kept out of reach of children because of a report of Reye's syndrome–like symptoms in a few babies who consumed 5 ml of the oil and ultimately died.¹⁴ No deaths have been reported in adults, but because of the potential for severe adverse effects, the amount of neem used should not exceed the amount that has been safely used in research studies. Adults may sometimes have diarrhoea, nausea, or stomach upset when taking neem oil.¹⁵ Neem should be avoided in pregnancy until its safety is demonstrated. Water extracts of neem leaf have been shown to decrease blood levels of chloroquine in rabbits, so these should not be combined until their safety can be demonstrated in humans.¹⁶

At the time of writing, there were no well-known drug interactions with neem.

References

1. Schmutterer H, Ascher KRS, Isman MB, et al, eds. The Neem Tree: Azadirachta indica A Juss and Other Meliaceous Plants. Weinheim, Germany: VCH, 1995.

2. Schmutterer H, Ascher KRS, Isman MB, et al, eds. The Neem Tree: Azadirachta indica A Juss and Other Meliaceous Plants. Weinheim, Germany: VCH, 1995.

3. Ad Hoc Panel of the Board on Science and Technology for International Development, National Research Council. Neem: A Tree for Solving Global Problems. Washington, DC: National Academy Press, 1992.

4. 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 Sci 2004;75:2867–78.

5. Pai MR, Acharya LD, Udupa N. The effect of two different dental gels and a mouthwash on plaque and gingival scores: a six-week clinical study. Int Dent J 2004;54:219–23.

6. Charles V, Charles SX. The use and efficacy of Azadirachta indica ADR ('Neem') and Curcuma longa ('Turmeric') in scabies. A pilot study. Trop Geogr Med 1992;44:178–81.

7. Garg S, Taluja V, Upadhyay SN, Talwar GP. Studies on the contraceptive efficacy of Praneem polyherbal cream. Contraception 1993;48:591–6.

8. Rembold H. The azadirachtins—their potential for insect control. Econ Med Plant Res 1989;3:57–72.

9. Schmutterer H, Ascher KRS, Isman MB, et al, eds. The Neem Tree: Azadirachta indica A Juss and Other Meliaceous Plants. Weinheim, Germany: VCH, 1995.

10. Khare CP. Indian Herbal Remedies. Berlin: Springer, 2004.

11. Pai MR, Acharya LD, Udupa N. Evaluation of antiplaque activity of Azadirachta indica leaf extract gel—a 6-week clinical study. J Ethnopharmacol 2004;90:99–103.

12. 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 Sci 2004;75:2867–78.

13. Mishra AK, Singh N, Sharma VP. Use of neem oil as a mosquito repellent in tribal villages of Mandla district, Madhya Pradesh. Indian J Malariol 1995;32:99–103.

14. Sinniah D, Baskara G, Looi LM, Leong KL. Reye-like syndrome due to margosa oil poisoning: Report of a case with postmortem findings. Am J Gastroenterol 1982;77:158–61.

15. Caius JF, Mhaskar KS. The correlation between the chemical composition of anthelminthics and their therapeutic values in connection with the hookworm inquiry in the Madras Presidency. Indian J Med Res 1923;11:353–70.

16. Nwafor SV, Akah PA, Okoli CO, et al. Interaction between chloroquine sulphate and aqueous extract of Azadirachta indica A. Juss (Meliaceae) in rabbits. Acta Pharm 2003;53:305–11.

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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires August 2007.