The neem tree, whose scientific name is Azadirachta indica, has been known for thousands of years in traditional Indian, Greek and Chinese medicine, before moving in recent decades to modern research laboratories as one of the plants rich in natural compounds with potential effects on health.
Neem belongs to the Meliaceae family, and is spread in tropical and subtropical regions, especially in India, Pakistan, Bangladesh and Nepal. Scientific interest in it is due to it containing more than 400 plant chemical compounds, the most prominent of which are azadirachtin, nimbin, nimbidin, nimbolide, and limonoids.
Laboratory and animal studies indicate that these compounds may possess anti-inflammatory, anti-bacterial, and anti-fungal properties, in addition to potential roles in protecting the stomach from ulcers, regulating glucose levels, and slowing the growth of some tumors.
However, most of these results still require broader clinical trials on humans before neem can be treated as an approved treatment.
Neem as an anti-inflammatory
In 2004, researchers from India published in the journal Phytotherapy Research the results of an experiment that examined the effect of nimbidine, extracted from neem, on inflammation. The study was based on two experiments: the first in the bodies of rats that received nimbidine orally for 3 days, and the second in the laboratory by directly exposing the cells to this substance.
The researchers focused on two important types of immune cells associated with inflammation: macrophages and neutrophils. The results showed that nimbidine may inhibit the activity of these two cells, which opens the door to subsequent studies to test its effect on human cells and evaluate its potential use in inflammatory diseases.
In 2013, the journal Natural Product Research published a study by researchers from the Department of Pharmaceutical Chemistry at SRM University in India, which tested the analgesic and anti-inflammatory properties of an extract from the peel of neem fruits, along with the compound azadiradione, on animal models at a dose of 100 mg/kg. The study concluded that the two compounds showed an anti-inflammatory and pain-relieving effect, but it remained an animal experiment that alone is not sufficient to confirm effectiveness in humans.
Neem is an antibacterial, antiviral and antifungal
In the field of dentistry, scientists from the Department of Dentistry at SMBT College and Hospital in India searched for natural alternatives to sterilizing root canals, in which bacteria may grow that cause inflammation and irritation.
The study compared neem leaf extract, grape seed extract, and sodium hypochlorite at a concentration of 3%, which is one of the most commonly used materials in root canal sterilization. Fecal enterococcus bacteria (Enterococcus faecalis) were grown in Petri dishes (a shallow cylindrical container made of glass or plastic, with a lid), then the tested substances were placed in holes inside the bacterial medium, and their effect was measured through what is known as the zone of inhibition, that is, the area free from bacterial growth around the substance.
The results showed that neem leaf extract was superior to sodium hypochlorite and grape seed extract in inhibiting bacterial growth, but researchers recommended conducting clinical trials to evaluate its safety and suitability for human use.
At the level of viruses, in 2010, American researchers published in the journal Phytotherapy Research a study that tested the aqueous extract of dried neem bark against herpes simplex virus type 1 (HSV-1).
The study found that the extract may limit infection by reducing the ability of the virus to enter cells and weaken its spread between them, while calling for the precise identification of the active compound and studying its toxicity before thinking about developing treatments based on it.
As for fungal resistance, Indian researchers tested alcoholic neem leaf extract at different concentrations against three fungal strains: Aspergillus flavus, Alternaria solani, and Cladosporium. The results showed a clear ability to inhibit the growth of these fungi, especially the methanolic extracts against Aspergillus flora, but the results still require clinical studies to confirm effectiveness and safety.
Neem and hair health
The health of the hair and scalp is affected by external factors such as the sun, humidity, stress, and the use of inappropriate chemical products, and by internal factors such as nutrition, hormones, and genetic predisposition. When this balance is disturbed, dandruff may appear or hair loss may begin.
In 2024, Egyptian researchers published in the journal Scientific Reports a study that tested the effectiveness of a combination of neem and rosemary extracts against scalp fungi. The mixture was prepared in two topical forms: a hair gel and a leave-on tonic.
The study was based on measuring the zone of inhibition in Petri dishes containing the targeted fungi, and the results showed significant effectiveness against the fungus Malassezia furfur, which causes dandruff, and the fungus Trichophyton rubrum, which is associated with scalp problems, compared to ketoconazole, which is one of the most popular anti-fungal treatments for the scalp.
The researchers attributed this result to an increase in the concentration of flavonoids and phenols when combining neem and rosemary, which enhances their anti-inflammatory and antioxidant properties. However, the study recommended conducting clinical trials on humans before approving these preparations.
In a clinical study conducted by Bharati Vidyapeeth University, neem leaf paste was used topically on the scalps of 100 participants aged between 18 and 24 who were suffering from moderate to severe dandruff. After two weeks, the dandruff completely disappeared in 44% of neem users, compared to only 4% in the control group.
Although the result appears promising, the study has important limitations; It was limited to females from one geographic region, and the control group did not use a placebo, and factors such as diet, stress, and hair care habits were not controlled.
Neem and skin care
Neem extract is used in many skin care products, and its cosmetic use in India is said to go back about 5,000 years. But modern scientific studies on this use are still limited, and most of them were conducted on animals or in laboratories.
In South Korea, researchers tested the effect of topical neem leaf extract on hairless laboratory mice with skin damage caused by ultraviolet radiation. The experiment showed that the extract improved skin appearance and reduced wrinkles by stimulating the production of collagen and elastin, and reducing inflammation and oxidative stress. Researchers linked this effect to rutin found in neem leaves, emphasizing the need for human studies.
In the field of acne, the Journal of Acute Disease published in 2013 an Indian study that used nanotechnology to load neem oil into nano-lipid particles, with the aim of improving its absorption and reducing skin irritation. The results showed that this formulation may be useful in treating acne, with the advantage of slow release of the active ingredient, which prolongs its therapeutic effect.
Is neem safe?
Despite the common image of neem as a natural plant, its use is not without risks, especially when taken orally or used in uncontrolled doses.
Topically, neem oil may cause allergic contact dermatitis in some people, and its long-term effect on the skin remains to be determined. Swallowing it may lead to vomiting, diarrhea, drowsiness, and metabolic acidosis, and in severe cases, it may lead to liver or kidney poisoning.
The risk increases in children, as medical reports have documented cases of neem oil poisoning that were associated with toxic encephalopathy and a syndrome similar to Reye’s syndrome, with symptoms such as vomiting and liver complications.
In 2015, the International Journal of Nanomedicine published a study by researchers from VIT University in India that tested the effect of neem nanoemulsion on human lymphocytes.
The study found that it is safe at low concentrations, but it showed clear cellular toxicity at concentrations between 1.2 and 2 mg/ml, as it caused oxidative stress and DNA damage.
Therefore, neem can be viewed as a promising plant in the fields of inflammation, hair and skin care, and resistance to some microbes, but it still needs stronger clinical evidence, and it should not be used as an alternative to medical treatment or taken internally without consulting a specialist.
