Can neem oil be used to treat head lice?
BACKGROUND
The neem tree is a fast-growing tree, native to India and other tropical parts of Southeast Asia. Its local names translate as “heal all” and “village pharmacy”. The traditional Indian medical system, Ayurveda, has recommended its use for thousands of years. It is most frequently used as a topical pesticide for use on the skin. Farmers also mix it with seeds before storing them to prevent infestation by fungi or insects.
Interest in natural pesticides has grown recently for a number of reasons. Concerns exist about the adverse effects of synthetic chemicals. Resistance has been developing to these chemicals, particularly with head lice treatments. The prevalence of head lice has been growing worldwide, especially in areas such as Europe, the US and Australia. Up to 80 per cent of the head lice removed from children in the UK have been found to be resistant to chemicals commonly used to eradicate them.
Contrary to popular belief, head lice infestations are not related to poverty or personal hygiene. They are most common in primary school children. The lice themselves rarely cause direct harm, and are not known to transmit infectious agents. However, they are irritating, can cause children to lose sleep, and excessive scratching can lead to infections. One of the biggest sources of harm is from inappropriate agents used in attempts to eradicate lice.
Natural treatments for head lice have been sought for years. Extracts and oils made from neem seeds have generated much interest – and some controversy. In 1995, a US company and the US Department of Agriculture were awarded a patent for a neem product by the European Patent Office. A 10-year legal battle ensued, with Indian authorities claiming that the patent denied the value of traditional knowledge and amounted to bio-piracy.
The case was settled in 2005, with the patent withdrawn. This set an important precedent supporting traditional knowledge over commercial interests. Since then, numerous neem products have entered the market, including several shampoos marketed for head lice.
EVIDENCE FROM STUDIES
Beginning in the 1940s, numerous chemicals were isolated from neem extracts. Many were shown to be active against a wide variety of microbes and insects. Head lice were collected from Australian children and placed in petri dishes containing either neem shampoo, permethrin (a chemical agent used to treat lice) or a control solution.
The neem shampoo was the most effective, with lice killed within five minutes. Neem extracts were also found to be active against various types of lice infesting horses and dogs.
A very small number of studies have been carried out with children infested with lice. In one study, 60 children who were heavily infested were treated with neem shampoo.
Their hair was combed out after five, 10, 15 and 30 minutes and the scalp inspected. The vast majority of the lice were dead within 10 minutes, with no evidence of skin irritation, burning sensations or other adverse effects.
PROBLEMATIC ASPECTS
Neem oil has been the source of concerns since two Indian children died after consuming it. They were mistakenly given relatively large amounts. However, the oil may have been contaminated, and numerous other studies have found neem extracts to be safe. A review of all the neem toxicological data concluded that neem products were safe so long as due care was taken with them. Neem shampoo should be kept out of the reach of young children.
RECOMMENDATIONS
Extracts and oils made from neem have a long history of use against microbes and insects. The products have been shown to kill lice rapidly and to be safe. Although very few studies have been carried out with humans, they confirm laboratory findings. Its safety profile is good, especially as the shampoo is recommended for short application (10 minutes) and to require only one or two applications. As a natural treatment for head lice, neem products show much promise.
Dónal OMathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University.
