Monoterpenoids and tetralin as pediculocides.

Sir, The increasing resistance of head lice to established insecticides means that patients and parents are seeking alternative effective treatments (1). Essential oils, including tea tree oil and Biz Niz, are promoted as treatments for head lice by alternative medicine therapists. Tea tree oil is the essential oil steam distilled from the leaves and terminal branches of tea trees, in particular the Myrtle tree (Melalenca alternifolia) (2). It is a complex mixture of over 100 hydrocarbons and terpenes. Of the 15 compounds found in highest concentration, 12 are monoterpenoids. These include terpinen-4-ol (30%), 1,8 cineole (15%), p cymene, a pinene, a terpinene, a terpineol and c terpinene (3). a terpineol is also an insipient ingredient in some standard insecticide containing louse treatment lotions which are felt to be more effective (4). A 1% copper oleate shampoo (which also contains tetralin) has been shown to be an effective treatment in 1 clinical trial (5). We examined the potential pediculicidal activity of tea tree oil, copper oleate, tetralin, terpinen-4-ol, a terpeniol and c terpinene, using in vitro exposure tests with freshly collected live adult head lice.