8 Side Effects Of Neem You Should Be Aware Of

Written by Ravi Teja Tadimalla

Neem is an evergreen tree native to the Indian subcontinent. It has been used extensively in ancient Ayurvedic medicine. However, excess use of its leaves has been linked to side effects. Some of these adverse effects could be fatal. In this post, we have discussed the possible side effects of neem leaves and the possible right dosage.

What Is Neem?

Neem is a tree whose different parts are used for different medicinal purposes.

  • Neem leaves are used to treat leprosy, eye ailments, upset stomach, and liver problems.
  • The bark is primarily used for malaria, ulcers, and fever.
  • The flower is used for reducing bile, controlling phlegm, and treating intestinal worms.
  • The fruit is used for treating hemorrhoids, phlegm, wounds, and diabetes.
  • Neem twigs are used for cough, urinary disorders, and intestinal worms. They are also used as a replacement for a toothbrush helping maintain oral health.
  • The juice of the leaf is one of the most effective toners and astringents. It can also be used to treat lice.

Despite the benefits, neem comes with a number of side effects as well. They are discussed in the next section.

What Are The Side Effects Of Neem Leaves?

  1. May Cause Allergic Reactions
  2. May Lead To Reduced Fertility
  3. May Cause Miscarriage
  4. May Cause Kidney Damage
  5. May Lower Blood Sugar Way Too Much
  6. May Lead To Infant Deaths
  7. May Cause Stomach Irritation
  8. May Over-Stimulate Your Immune System

1. 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 (1).

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.

2. 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 (2).

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 (3).

Neem had caused 90% deaths at the end of six weeks in rabbits (3).

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. They are known to disrupt the direction of the sperms and take a toll on the immune system. However, research is lacking in this aspect.

3. May Cause Miscarriage

In animal studies, extracts of neem 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 (4).

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.

4. 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 (5).

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 (5). 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.

5. 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 hypotensive properties (6).

Though the hypotensive 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 diabetic patients as it controls blood sugar levels. But, when taken in excess, the drop may become extreme. Hypoglycemia may cause dizziness and weakness (fatigue) (7).

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 present 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, experts advise against the use of heavy doses of neem (especially in patients with ailments). In such patients, neem may overstimulate their 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.

There is less information to state the ideal dosage of neem. Anecdotal evidence suggests that one to two leaves a day could be fine. But we recommend you consult your doctor before consuming neem.

Expert’s Answers For Readers’ Questions

Can you eat neem leaves daily?

Yes, you may. But if you have any health condition, please talk to your doctor.

Is neem safe your eyes?

Neem may cause eye irritation. Intake of neem may be safe for your eyes. However, a study states a case of optic neuropathy in an individual after consuming neem oil (12).

12 sources

Articles on StyleCraze are backed by verified information from peer-reviewed and academic research papers, reputed organizations, research institutions, and medical associations to ensure accuracy and relevance. Check out our editorial policy for further details.

Recommended Articles

Was this article helpful?
The following two tabs change content below.
Ravi Teja Tadimalla is an editor and a published author. He graduated from SRM University, Chennai, and has been in the digital media field for over six years. He has a Professional Certificate in Food, Nutrition & Research from Wageningen University. He considers himself a sculptor born to chip away at content and reveal its dormant splendor. He started his career as a research writer, primarily focusing on health and wellness, and has over 250 articles to his credit. Ravi believes in the great possibilities of abundant health with natural foods and organic supplements. Reading and theater are his other interests.