What It Is
Permethrin belongs to a class of medicines called pyrethroids, which are synthetic versions of natural insecticides found in chrysanthemum flowers. It is applied to the skin or hair as a cream or lotion.
What It's Used For
Permethrin is generally used to treat scabies, an itchy skin infestation caused by tiny mites, and head lice. For scabies, the cream is applied over the whole body from the neck down and washed off after several hours. Close contacts and household members are often treated at the same time.
How It Works
Permethrin acts on the nerve cells of mites and lice, keeping their sodium channels open. This causes paralysis and death of the parasite. Very little is absorbed through human skin, and what is absorbed is quickly broken down, which is why it is considered safe for most people, including children.
History and Regulatory Status
Permethrin was developed in the 1970s and came into medical use in the 1980s. It is included on the World Health Organization's list of essential medicines. Lotions for head lice are available without a prescription in many countries, while stronger creams for scabies are usually prescribed. It is also used on clothing, bed nets, and bedding as an insect repellent.