Pediculicides

Pediculicides are substances used to kill lice, primarily Pediculus humanus capitis (head louse) and, less commonly, Pediculus pubis (pubic louse) infestations. They include topical preparations, oral medications, and, in some cases, non-chemical products that physically disrupt or suffocate the lice.

Common chemical pediculicides include pyrethroids such as permethrin and pyrethrins (often combined with piperonyl butoxide), and organophosphates such as malathion. Ivermectin can be taken orally or applied topically in some formulations. Spinosad and benzyl alcohol are other registered options. In addition, physical agents such as dimethicone or mineral oil–based products suffocate lice and are widely used as non-neurotoxic alternatives.

Application typically involves applying the product to dry hair or scalp for a specified period, then rinsing. A second treatment after 7–10 days is often recommended to kill newly hatched nymphs. Nits on the hair shafts may persist after treatment and should be removed with a comb. Avoid contact with eyes and mucous membranes; wash hands after use.

Safety and resistance: Most products are safe when used as directed but can cause skin irritation or rare allergic reactions. Populations of lice with resistance to pyrethroids have been reported, reducing effectiveness; alternative agents or combination regimens may be advised by a clinician.

Regulatory status: In many countries, pediculicides are available over the counter; some agents such as oral ivermectin require a prescription. Pregnant or breastfeeding individuals and young children should seek medical guidance before use.