8 Side Effects Of Neem You Should Be Aware Of

Written by Ravi Teja Tadimalla , Professional Certificate In Food, Nutrition & Health

Neem is especially known for the benefits it offers in treating various ailments. But do you know that it may also cause side effects if taken in excess? A dosage of 1 to 2 leaves per day or 4 ml of neem juice for a period of 10 weeks is usually considered safe. Anything more than that, unless medically advised, may cause potential negative effects.

Here, we discuss the major side effects of neem and the precautions you must take for the same. Read on.

What Are The Side Effects Of Neem Leaves?

1. May Cause Kidney Damage

A study reports of a case of acute renal failure in an individual after taking a Chinese herbal medication. The medication, as per the report, contained neem as one of the primary ingredients (1). Though no direct link had been established between neem intake and kidney damage, it is important to be careful. The trend of toxic renal injuries with respect to herbal medicines is likely to continue (1). Hence, exercise caution.

Some believe that excess intake of neem may also damage the liver. There is no research to support this. But to be on the safe side, if you have liver issues, please consult your doctor before consuming neem.

2. May Lower Blood Sugar Way Too Much

In a study, a combination of neem and longevity spinach (a type of spinach found in China) was found to have hypoglycemic properties (2).

Though the hypoglycemic effects of neem seem desirable, if you are on medications for lowering blood sugar, please check with your doctor before ingesting neem.

Doctors recommend small amounts of neem oil for individuals with diabetes as it controls blood sugar levels. But, when taken in excess, the drop may become extreme. Hypoglycemia may cause dizziness and weakness (fatigue) (3).

3. May Lead To Reduced Fertility

In rat studies, the administration of neem flower extracts blocked ovulation partially. Though neem could be used as an antifertility agent when required, it may also reduce fertility even when not desired (4).

In studies done on rats, mice, rabbits, and guinea pigs, neem was found to reduce male fertility. In male rats, this reduction was as much as 67% in just six weeks. However, neem didn’t seem to stop sperm production (5).

Some experts theorize that farmers use neem pesticides to cause infertility in the pests so that they do not multiply, resulting the same in individuals who expose themselves to these pesticides. These pesticides are known to disrupt the direction of the sperms and take a toll on the immune system. However, research is lacking in this aspect.

4. May Cause Miscarriage

In animal studies, neem extracts were found to induce pregnancy. The extracts could terminate a pregnancy with no visible side effects in both rodents and monkeys. Though this could be desirable for someone looking to abort the child, for those who are expecting to conceive, neem intake may not be recommended (6).

Some theories state that overexposure to neem may cause the immune system to become hyperactive. This could lead the body to reject the sperm cells and eject them from the conceived embryo. However, there is insufficient information to substantiate this.

5. May Cause Allergic Reactions

A study discusses a case of allergic contact stomatitis (inflammation of the mouth) after the intake of neem leaves once every week for three consecutive weeks (7).

Though neem is most commonly used for treating allergies and rashes, its excessive use may lead to allergies. We need more research to further understand the other allergies the use of neem may cause.

6. May Lead To Infant Deaths

Studies have shown that neem could be toxic to infants. Doses of neem oil (as small as 5 ml) had resulted in infant deaths (8).

Animal studies also showed the toxicity of neem oil at doses as low as 12 to 24 ml per kilogram of body weight (9).

Though the contaminants in neem oil could be responsible for these effects (and not neem itself), more research is warranted. Neem leaves or their extracts must not be consumed for longer periods. Anecdotal reports state kidney failure in patients who consumed neem leaf teas as a treatment for malaria (10).

The substances in neem are known to cause symptoms of Reye’s syndrome in infants when exposed to neem oil. The consumption of the smallest dosage can be fatal for infants (11).

Insufficient Evidence For The Following

There is less information and research about the following side effects. These have only been validated by anecdotal evidence. However, if you experience any of these side effects after ingesting neem, please stop use and consult your doctor.

7. May Cause Stomach Irritation

Excess inhalation or consumption of neem may cause indigestion or stomach irritation. More research is needed to understand how this happens.

8. May Overstimulate Your Immune System

Consumption of neem or neem-based products can boost the immune system. However, heavy doses of neem (especially in patients with ailments) may overstimulate the immune system and cause complications.

Patients who have undergone organ transplants may also need to stay away from neem. The leaves are believed to interact with immunosuppressant medications during surgeries.

However, there is insufficient information in this regard.


Neem is among the more important plants used in Ayurvedic medicine. Most of its benefits have been extensively researched. However, excess intake seems to cause undesirable effects. This is especially true in the case of infants and children.

Anecdotal evidence suggests that one to two leaves a day could be fine. But we recommend you consult your doctor before consuming neem.

Frequently Asked Questions

Is neem safe for your eyes?

Neem may cause eye irritation. In a study, an individual who had consumed neem oil had developed optic neuropathy (12). Hence, do not use neem directly on your eyes. If you have any eye ailments, consult your doctor before consuming neem oil.

What happens if we eat neem leaves daily?

Regular consumption of neem leaves may reduce the severity of skin diseases, decrease gastric acid secretion, and help reduce ulcers (13). However, prolonged consumption beyond the recommended dosage is linked to side effects.

Does neem make skin dark?

No. There is no scientific evidence that says neem can make skin dark. In fact, extracts of neem bark and heartwood have phenolic properties, which can be attributed to skin whitening (14).


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  1. Acute Renal Failure Induced by Chinese Herbal Medication in Nigeria
  2. Hypoglycemic Effect of Combination of Azadirachta indica A. Juss. and Gynura procumbens (Lour.) Merr. Ethanolic Extracts Standardized by Rutin and Quercetin in Alloxan-induced Hyperglycemic Rats
  3. RSSDI clinical practice recommendations for the management of type 2 diabetes mellitus 2017
  4. Antifertility potential of Neem flower extract on adult female Sprague-Dawley rats
  6. nduced termination of pregnancy by purified extracts of Azadirachta Indica (Neem): mechanisms involved
  7. Allergic contact stomatitis caused by neem leaves (Azadirachta indica)
  8. Neem Oil Poisoning as a Cause of Toxic Encephalopathy in an Infant
  9. Acute toxicity study of the oil from Azadirachta indica seed (neem oil)
  10. Medicinals
  11. Margosa oil poisoning as a cause of Reye’s syndrome
  12. A rare case of toxic optic neuropathy secondary to consumption of neem oil
  13. Therapeutics Role of Azadirachta indica (Neem) and Their Active Constituents in Diseases Prevention and Treatment
  14. Critical review of Ayurvedic Varṇya herbs and their tyrosinase inhibition effect

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