Side Effects Of Neem You Should Be Aware Of

Azadirachta indica or neem is an extraordinary tree. Every part of the neem tree – bark, leaves, flowers, seeds, roots and fruits – has been used since ancient times for a wide range of purposes in ayurvedic, homeopathic, and unani medicine. In fact, it is known as the “Village Dispensary” in many Indian villages.

However, the very potent powers of neem, and neem oil in particular, could affect you adversely if used unwisely. A lay consumer often overlooks or is unaware of this fact. Here are some side effects of neem you should be aware of.

Neem Oil Can Irritate The Skin And Stomach Lining

Many neem-based products such as neem leaf extracts and neem teas are generally safe for ingestion. But neem oil, derived from the plant’s seeds, is potentially harmful if ingested.1 Azadirachtin, an active component of neem oil, can irritate the skin and stomach lining and cause mild to serious problems. The other components of neem oil include fatty acids, essential oils, and other constituents, all of which typically occur in other foods and can be safely consumed.2

Neem Oil Can Cause Nausea Or Diarrhea

Adults who ingest neem oil could suffer from nausea or diarrhea.3. These are the milder side effects, though. More serious effects can occur if you consume too much and the effects include kidney failure, seizures, or metabolic acidosis, which is a chemical imbalance in blood leading to a build-up of excessive acid. Many of these conditions can be managed with timely medical care, but fatalities are not uncommon.4


Neem Oil Can Cause Brain Damage

While neem oil is primarily a topical application, in some countries where it grows, there is a tradition of administering the oil in small amounts to newborns and infants. This practice carries huge risks. In children and some adults, neem oil can cause toxic encephalopathy, a neurologic disorder that causes vomiting and seizures. Other serious side effects observed include drowsiness and brain swelling. While precious lives are often saved with timely medical intervention, there are deaths too. Some babies who survive may have impaired neurological functions.5 Clearly, not all traditions are safe.

Neem May Cause Infertility

Since neem oil has been shown to have genotoxic (cell-damaging) properties in lab studies, pregnant and breastfeeding women should not ingest it. Neem may also induce abortion. Experiments on laboratory animals with neem have shown it to have spermicidal qualities and, hence, it should not be used by men or women wanting to become parents.6 On the good side, research indicates its potential as a vaginal contraceptive thanks to these same spermicidal properties.7


The Good And The Bad In Haircare And Skincare

Neem oil is excellent for both skincare and hair care. It’s rich in vitamin E and essential fatty acids (EFAs), and stimulates the production of collagen, making it an excellent antidote for dryness and aging skin. Neem oil’s antibacterial and anti-inflammatory properties can treat fungal skin infections such as athlete’s foot and ringworm. Hair loss, graying hair, dandruff, and lice are the various hair problems that can also be treated with neem oil.8

However, there have been rare cases of individuals reacting to topical applications of neem oil. For instance, when applied to the scalp to combat alopecia or hair loss, neem oil could lead to contact dermatitis or itchy rashes on the face and scalp.9 Always do a patch test before use and ensure you don’t use undiluted neem oil directly unless under medical supervision. Carrier oils like coconut and almond can be blended with it in the proportion 1:10 for sufficient effect. Neem oil is powerful enough to be effective at this concentration too.10


Effect On Vision

A study from India cites the rare instance of a woman who consumed a large quantity of neem oil and 5 days later, reported loss of vision. Fortunately, her eyes responded to treatment and she recovered her vision.11 While the report offers no details on the context surrounding her consumption of neem oil, the message is clear – indiscriminate use of neem oil can potentially harm our bodies in unforeseen ways.

Neem Oil: Should It Be Avoided At All Costs?

Not at all! Neem oil is already incorporated commercially in a range of everyday products for skincare, healthcare, dental care, and cosmetic use. In general, exposure to neem oil in such products is considered safe with no side effects, as the quantities will be balanced and safety-tested. So go right ahead if you love using herb-based toiletries and skincare products.12 Do a patch test or slowly increase quantities to ensure you are not allergic to the product.


Neem Leaf, Bark, And Seed: Do They Have Toxic Effects Too?

Neem stem bark extracts have long been used traditionally as a pesticide, a contraceptive, for dental care, rheumatism, and to treat gastrointestinal and skin problems. Scientific studies show that neem bark extract has antibacterial and antimicrobial properties, and it can treat children’s inflammatory conditions in the mouth, stimulate the immune system, and treat acidity and ulcers.

Ayurvedic medicines use neem bark extracts to treat pain and fever. It is considered to be safe with no known toxic effect on humans. It has been found to be toxic for certain snail and fish species but has not shown any toxic effect on mice during laboratory tests.13


Used under expert guidance, extracts of neem leaf, bark and seeds are considered safe for human use. In fact, like neem oil, they are already being used in various products for daily use. Traditional medicine does advise against unguided use of neem by children, women who are pregnant or trying to conceive, and all adults with a weak constitution.

Scientific studies show that aqueous extracts of neem leaves, when ingested in the right dosage, can stimulate the immune system, control blood sugar levels, prevent intestinal ulcers, inhibit fungal and viral growth, prevent oral cancer, protect the liver, and treat anxiety and depression. Neem leaf extracts can inhibit the growth and development of the malarial parasite and is an important part of malaria control programs. Neem leaf is also known to have spermicidal properties so must be avoided by pregnant women and by women, and their partners, who are trying to conceive.


Ayurvedic medicine has already been using neem leaves for centuries to treat health conditions such as skin problems, eye problems, intestinal worms, leprosy, nosebleeds, and bile problems. Animal lab tests have shown adverse effects in various degrees but no known toxic effects on humans have so far been observed.14

Neem seed use has shown mild to lethal toxicity in animal laboratory tests. On the other hand, ayurvedic medicines use seed extracts to treat intestinal worms and leprosy in humans.15Neem seed extracts are known to have spermicidal, anti-fungal, anti-microbial, and anti-viral properties. Its spermicidal properties have even been successfully used to formulate a cream.16

How Much Is A Safe Dose?

  • In traditional practice, about 2–4 grams of powdered neem leaf or 10–20 ml of neem leaf juice are safely prescribed twice or thrice a day.
  • About 1 gram of leaf extract gel or toothpaste used twice a day can effectively and safely remove dental plaque.
  • About 30-60 grams of freeze-dried neem bark extract has proven to be effective against stomach ulcers.
  • For skin and vaginal infections, creams with 5 percent or more of neem extracts or oil can be safely applied at least twice a day.
  • To effectively repel mosquitoes and other insects, a 4 percent concentration neem oil mixed with other oils such as mustard or coconut has been found safe and effective.17

As with any ingestible health product, a neem-based medication should only be taken when prescribed by qualified professionals who will also factor in possible side effects and interactions with medications for existing illnesses.18

Safety Of Neem Tea And Neem Capsules

Neem leaf extract capsules are commercially available in strengths of 250–500 mg as treatment for acne and other skin allergies and infections. The capsules can be safely taken twice a day under medical advice only. Please do not self-medicate.

Neem leaves are quite safely used to make teas or infusions to boost immunity and cleanse blood. However, more than 2 cups a day can make you nauseous, and suppress your appetite, so don’t overdo it. In many Indian homes, neem leaves are boiled in bath water to take care of skin problems. Sometimes a bandage or cloth is soaked in such a tea and bandaged over sprains, swollen glands, and bruises. This is safe and effective.