Lack of response to treatment of head lice

The resistance of head lice to neurotoxic insecticides is increasing, and can cause treatment failure. However, incorrectly applied treatment or re-infestation are also causes of treatment failure. Consider the possibility of re-infestation from other family members or close contacts—examine household members and close contacts, and treat if live lice are found.

For head lice that are resistant to an initial trial of a recommended topical insecticide, use a different topical treatment (see Treatment of head lice). Wet combing can also be trialled.

If head lice are refractory to all topical treatments, use:

ivermectin (adult and child 15 kg or more) 200 micrograms/kg orally with fatty food, as a single dose. Repeat dose in 7 days¹. ivermectin ivermectin ivermectin

¹ At the time of writing, ivermectin is not approved by the Australian Therapeutic Goods Administration (TGA) for this indication. See the TGA website for current information.Return