Lice, also known as Pediculosis capitis, live on human hair, feeding on tiny amounts of blood they draw from the scalp. Getting rid of lice is often difficult. Treatments with over-the-count insecticides are often toxic and may prove ineffective, especially if the lice have developed resistance. Neem oil is an alternative treatment to harsh chemicals.
Lice cannot jump, fly, or swim, but they easily transfer from one human to another by crawling, by direct head-to-head contact or by direct contact with fabrics harboring live lice. Once a louse drops off a human hair, it dies fairly quickly, in about two to three days, as they have difficulty crawling back onto a host, particularly if injured or weak from lack of a blood meal. Lice infestations occur more often in girls than in boys, though the reason is unclear.
During the lice life cycle, a female louse will feed on human blood and mate. After one or two days, she lays eggs on hair follicles close to the scalp, attaching them with a waterproof glue-like substance that cannot be washed out or blown out, as with a hairdryer. A single female louse can lay from 50 to 150 eggs. These eggs, called nits, hatch, producing nymphs. Within 10 days of hatching, the nymphs are ready to mate. Adults live approximately 9 to 10 days after mating. Thus, the entire lifespan of the louse is at least 20 days.
Standard insecticide treatments kill lice by attacking their nervous system. Nits do not have nervous systems and therefore are unaffected by insecticide treatments. Removing adherent nits with a fine-toothed comb helps prevent reinfestation but is often difficult, especially for people with very thick, long hair. Even one missed nit will result in a new louse born that can then lay another 50 to 150 eggs.
Neem oil is a vegetable oil obtained from Azadirachta indica, an evergreen tree native to India. Extracts from the fruits and seeds of the plant yield a light orange to dark brown, thick oily substance that has a very pungent odor. It is not soluble in water. The active ingredient of neem oil against lice appears to be azadirachtin, an organic tetranortriterpenoid molecule similar to an insect molting hormone, which disrupts the insect life cycle. Other components such as steroids and triterpenoids are also part of neem oil composition.
Treating an infestation with neem oil requires the removal of all lice--live, dead and nits. To begin the process, wash the hair with a shampoo to which a small amount of pure neem oil has been added. Work the shampoo into the hair and leave it on the head to incubate for at least 10 minutes. Rinse off the shampoo, and use a conditioner to make subsequent combing easier. Towel-dry the hair.
Apply undiluted neem oil to the hair and comb it through, removing any lice or nits in the process. Seal up the lice or nits in a bag and dispose of it in the trash to prevent resinfestation. To further suffocate any remaining lice, wrap the hair in plastic wrap and put on a plastic disposable shower cap overnight. Repeat this procedure daily for up to two weeks to ensure that all lice have been removed.
Neem oil effectively kills lice in all stages of their life cycle. While the mechanism appears to be through the action of the azadirachtin, there are other theories as well. Neem oil appears to inhibit the effect of the eating and biting behavior of the lice, essentially decreasing their appetite to the point of starvation. Neem oil's pungent odor may repel lice, thus acting as a prophylactic agent.
- Medical Entomology Centre: FAQ Lice
- Springerlink: Parasitology Research: Efficacy of neem seed extract shampoo on head lice of naturally infected humans in Egypt
- The Lifcycle of Lice
- Beyond Pesticides: Head Lice Control
- Springerlink: Effects of two different neem products on different stages of Nezara viridula (L.) (Heteroptera, Pentatomidae)