TABLE 1.

Topical insecticides for treatment of head lice infestations

	Trade name	Active ingredient	Method of use in brief	Areas of concern
Pyrethrins
- resistance documented in Czech Republic, Argentina, France, Israel and United Kingdom (5)	- R&C Shampoo/Conditioner†	- pyrethrin plus piperonyl butoxide - made from natural extracts from chrysanthemums - neurotoxic to lice but very low toxicity to humans	- apply to dry hair that does not have conditioner, gels, creams, etc, on it - soak with minimum of 25 mL - let sit 10 min - add small amount of water to form lather and work into hair - rinse well with cool water over a sink, rather than in a shower or bath, to minimize body exposure - repeat treatment 7 to 10 days later	- true allergic reactions are rare - possible allergic reactions if allergic to ragweed - may cause itching or mild burning sensation of scalp*
Permethrin
- resistance documented in Czech Republic, Argentina, France, Israel, United Kingdom and United States (5,18)	- Kwellada-P Creme Rinse† - Nix Creme Rinse‡	- 1% permethrin (synthetic pyrethroid) - neurotoxic to lice, very low human toxicity	- after washing hair with conditioner-free shampoo, rinse, towel dry - apply enough permethrin creme rinse to saturate hair and scalp - leave on for 10 min - rinse well with cool water over a sink, rather than in a shower or bath, to minimize body exposure - towel dry - repeat in 7 days*	- does not cause allergic reactions - may cause itching or mild burning sensation of scalp*
Lindane
- resistance documented in England, Netherlands and Panama (5,19)	- Hexit Shampoo§ - PMS-Lindane Shampoo¶	- 1% lindane (gamma benzene hexachloride) - an organochloride with properties similar to DDT - very neurotoxic to lice but also to humans	- apply to dry hair that does not have conditioner, gels, creams, etc, on it - apply this shampoo over a sink, not in the shower or bath, to minimize body exposure - apply minimum amount to thoroughly wet hair and scalp - rub shampoo into hair and scalp, allow to remain in place for 4 min, use just enough water to form a good lather - rinse thoroughly with cool water and dry with a clean towel	- possible neurotoxicity, including seizures - possible anemia - contraindicated if there is a history of seizures - occasional irritation of scalp* - not recommended for infants

^*Itching and burning sensation of the scalp, which occurs following treatment, does not necessarily indicate reinfestation and need for retreatment. If bothersome, topical steroids and antihistamines may be helpful (9);

^†GlaxoSmithKline Consumer Healthcare, Canada;

^‡Insight Pharmaceuticals, Canada;

^§Odan Laboratories Ltd, Canada;

^¶Pharmascience Inc, Canada (according to the Compendium of Pharmaceuticals and Specialties 2000. Ottawa: Canadian Pharmacists Association, 2000). DDT Dichlorodiphenyltrichloroethane