For over 4,000 years, the neem tree has been used in traditional medicine. Abundant in bioactive compounds, neem is a natural antiseptic that can be used on the skin, hair, in cosmetics, on pets, and in the garden. The oil may even work as a cheap, natural contraceptive. If you’re as intrigued as we were, read on to learn more about this plant.
It’s been used in Ayurvedic medicine, a system of traditional medicine that originated in India, for over 4,000 years [3+].
Virtually every part of the tree, including the bark, seeds, leaves, flowers, and roots, have traditional medicinal uses. For example, chewing neem twigs is a common method for keeping the teeth clean in some rural Indian populations [4, 5, 6].
Neem oil usually refers to the oil obtained from neem seeds, although extracts from other parts of the tree, like the leaves, are also sometimes called ‘neem oil’. The oil has a yellow color and reportedly smells like garlic [7+, 8+].
- May improve oral health
- A natural pesticide
- May improve skin and hair health
- Potential as a birth control method
- Extracts might be useful for HIV and diabetes
- May be used for skin problems in pets
- Research on all potential benefits is limited and some studies are flawed
- Can cause ‘neem oil poisoning’ and allergic reactions
- Wide variety of formulations with different effects
Over 300 compounds have been identified in neem .
Neem oil also contains a group of compounds called limonoids, the most well-known of which is azadirachtin. The plant makes these compounds to deter predators, and they are likely responsible for many of its bacteria- and pest-killing properties [12, 13].
Many of these compounds are found in some amount in all parts of the tree, although their levels can differ between the leaves, seeds, and other plant parts. Neem oil is made from the plant seeds .
Pure neem oil can be applied directly to the skin or hair. It is also added to beauty products, often in combination with other oils, herbs, or active compounds. Additionally, pills with neem extracts may be more effective for some skin conditions than the oil. This section covers the health benefits of both the oil and the extracts.
Studies including over 130 healthy people found that neem-based mouthwashes improved oral health. Neem-based mouthwashes reduced plaque, decreased gum inflammation, and killed mouth bacteria just as much as, or more than, a standard mouthwash [16, 17, 18, 19].
A study including 45 people with gum disease (gingivitis) found that a neem-based mouthwash reduced symptoms such as gum bleeding and the buildup of plaque just as well as a standard of care mouthwash .
Additionally, one study including 50 healthy people reported that chewing neem sticks was equally as effective at keeping the mouth clean as using a toothbrush. Stick chewers even had a greater reduction in plaque than tooth brushers .
The following purported benefits are only supported by limited, low-quality clinical studies. There is insufficient evidence to support the use of neem oil for any of the below-listed uses. Remember to speak with a doctor before taking neem oil and never use it as a replacement for approved medical therapies.
Aside from herbal combinations, taking extracts from neem alone may improve skin diseases. In a study of 50 people with psoriasis, an extract from its leaves in addition to standard treatment reduced symptoms after 3 months better than standard treatment alone [29+].
Neem oil is anecdotally lauded for its ability to keep the skin healthy and looking young, but there isn’t much solid science to back up these claims.
One study did find that an extract of neem leaves prevented UVB-induced wrinkling in mice. In this study, neem reduced free radicals, which blocked enzymes that break down collagen. As a result, it boosted the production of both collagen and elastin – two key skin-protecting compounds needed to maintain youthful, healthy skin .
Additionally, neem may help skin wounds heal faster. In a study of nine people, oil from neem and St. John’s wort applied as a skin dressing safely enhanced the healing of scalp wounds following surgery when. However, this study lacked a control group .
To sum up, the effects of neem oil on acne have been investigated in low-quality studies with multiple flaws, only one study attests to its effectiveness at improving psoriasis, its effects on skin appearance have only been tested in animals, and the only clinical trial using it to heal wounds was small and flawed. Larger, higher-quality clinical trials are needed to validate these preliminary results.
One study including 60 children with lice reported that a treatment including a neem extract-containing shampoo was effective, but due to the lack of a control group, it’s impossible to say whether the plant extracts themselves were beneficial .
Although there are numerous claims that neem oil can help with dandruff, there haven’t been rigorous studies in humans to back these claims up. However, neem oil can prevent the growth of dandruff-causing bacteria and fungi in dishes [39, 40, 41+, 42+].
Similarly, whether neem oil can promote hair growth or prevent baldness in humans hasn’t been thoroughly tested, though there is an abundance of anecdotal evidence. Neem oil did speed up hair growth in rabbits [8+, 43+, 44+].
All in all, only a few clinical trials with mixed results and some animal research have investigated the role of neem oil in fighting off head lice and promoting hair health. Further clinical research is needed to shed some light on these potential benefits.
Neem oil is used as a contraceptive in some parts of India. It’s been suggested as a natural and cheap means of population control. It would be especially beneficial for rural populations that don’t have access to other types of birth control. Some consider this may be neem’s greatest untapped potential. But whether or not neem oil is an effective contraceptive is still far from certain .
In a study of 242 women, over 95% of those who applied neem oil vaginally as a contraceptive did not become pregnant for at least one year. These women also had fewer urinary tract infections [46+].
Another older study claimed that applying neem oil to the vagina before sex was 100% effective at preventing pregnancy in humans. However, the data from this study – including details like how many people were included – isn’t available, so there’s not much backing up this claim .
In monkeys, neem oil applied to the vagina significantly reduced the likelihood of conception. Although studies agree that neem oil applied before mating is effective for preventing pregnancy in monkeys, there is disagreement about its effectiveness when applied after mating [48, 49, 50].
An injection of neem oil into the uterus of female rats decreased conception rates for several months, and this effect eventually wore off. An injection into male rats also rendered them infertile, which lasted for the duration of the 8-month study [51, 52].
In rodents and primates, neem extracts given early in pregnancy ended it .
Until high-quality clinical trials are available, neem oil should not be used as a means of birth control; its efficacy and safety are still unclear.
One study used a paste containing neem and turmeric to treat 814 people with scabies, and 97% of cases were cured within 2 weeks. However, this study lacked a control group .
An uncontrolled clinical trial and some animal research cannot be considered sufficient evidence that neem oil helps with scabies. Further, better-designed clinical trials are required.
In a small study of 28 people with head and neck cancer, a treatment including neem oil and St John’s wort reduced skin irritation from radiation therapy. However, this study didn’t have a control group, making it impossible to rule out the placebo effect .
In mice and rats given cancer-causing chemicals, neem extracts prevented the development of tumors and pre-tumor lesions; the tumors that did develop were generally smaller than those in controls [1+, 58, 59, 60].
Again, an uncontrolled trial and some animal research are insufficient to back up this potential health benefit of neem oil.
No clinical evidence supports the use of neem oil for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies should not be interpreted as supportive of any health benefit.
Directly tied to many of its benefits – including those for skin, hair, and oral health – neem oil is a potent antiseptic. In numerous studies, the oil could kill or prevent the growth of disease-causing bacteria and fungi. These include bacteria that can cause foodborne illness and that can be life-threatening for HIV patients or those with weakened immune systems [65, 12, 66, 67, 68, 69].
Neem Oil Repels Insects and Pests
As An Insecticide
Neem oil applied to the skin can repel mosquitoes for up to 12 hours. It can also be burned to repel mosquitoes. However, its effectiveness varies somewhat based on the species of mosquito [70, 71, 72, 73].
Neem is also used as a natural pesticide to protect plants and seeds from pests feeding on them. In labs, neem oil is lethal against multiple pest species, including crop-eating moths and mosquitoes [78, 79, 80, 81, 82].
Neem oil may be safe to use in dogs. It has also been marketed in products for cats and may be safe at low doses; however, there are reports of neem oil causing dangerous side effects in some cats [83+, 84+].
A combination of neem oil applied to the skin and eating neem leaves was as effective as a standard treatment at removing mites from dogs. A neem-containing shampoo was similarly effective at removing mites causing scabies [87, 88].
A neem-containing cream was effective at treating a fungal infection in horses .
Potential Benefits of Neem Extract
Neem extracts may have a wider spectrum of benefits than the oil (which should not be ingested). The following potential health benefits do not apply to neem oil but only to the extracts prepared from neem leaves. Only extracts can deliver active compounds from neem to the bloodstream.
The following purported benefits are only supported by limited, low-quality clinical studies. There is insufficient evidence to support the use of neem extracts for any of the below-listed uses. Remember to speak with a doctor before taking neem extract supplements and never use them as a replacement for approved medical therapies.
Similarly, 10 people with HIV were given a neem leaf extract in another study. The extract increased their white blood cell count after one month .
Two small clinical trials and some cell-based research cannot be considered sufficient evidence that neem extracts help fight HIV. Larger, more robust clinical trials are needed to confirm these preliminary results.
In a study of 90 men with diabetes, pills with neem leaf powder reduced diabetes symptoms like tiredness, hunger, and headache. However, the study lacked a control group, making it difficult to rule out a placebo effect .
An uncontrolled clinical trial and some animal research are clearly insufficient to support the use of neem extracts in diabetics. Further, unflawed clinical trials are needed.
No clinical evidence supports the use of neem extracts for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies should not be interpreted as supportive of any health benefit.
Neem improved coordination in rats with nerve damage. Extracts from neem leaves could also protect rat brain cells from damage caused by chemotherapy; neem-treated rats had less brain cell death and showed fewer signs of tissue damage in the brain [102, 103].
Data on neem in humans is limited, and many of the available studies have serious flaws, including lacking control groups and failing to report important details about treatments. Most human studies were also very small, so it’s hard to generalize their results [47, 26, 94].
A number of studies in humans used relatively subjective measurements – like the appearance of acne. Although not necessarily disqualifying, such studies are more susceptible to bias, especially when proper controls aren’t included [26, 27+, 28+].
Several studies used combinations of herbs including neem. Although herbal treatments were often reported to be effective, it’s impossible to say whether any single ingredient, like neem, would be effective on its own [26, 27+, 28+].
Neem oil can be used to improve the appearance of skin and hair and enhance oral health, although the scientific evidence is limited. Scientists think it might also be a cheap and safe spermicide, but more research is needed before its birth control use can be recommended.
While neem oil is usually made from the seeds, extracts are typically prepared from the leaves. Both have some similar active compounds, but the extract is likely more concentrated.
Preliminary research suggests neem extracts may be beneficial for people with diabetes and might protect the heart, kidneys, and brain from toxins. Although extracts may have a wider spectrum of health benefits than the oil, they are also much more likely to cause side effects.
Beyond its health applications, neem may be useful as a natural insecticide and pesticide.