When recommending a head lice treatment, bear in mind that multiple family members may need to use it, so check all ages, especially of younger children. Remember to enquire about pregnancy and asthma as some products contain solvents that may not be suitable. Ask the WWHAM questions and refer to your pharmacist when necessary.

Check that customers buy sufficient product (a small bottle for short or shoulder length hair or a larger bottle for longer or thicker hair) for every infected person to use at the same time and make sure that they understand how to use the product correctly. Are they, for instance, aware of how long the treatment should be left on the hair, and if they should reapply it?

1. Physical insecticides

These contain ingredients such as cyclomethicone, isopropyl myristate and dimeticone, which kill lice by physical means (e.g. by blocking the tubes that lice use to breathe or by causing dehydration). Lice cannot become resistant to these products.

Physical insecticides are effective against live lice, but while some also target unhatched eggs, others require a second application after seven days to kill any lice that may have hatched since the first application. They are available in a range of formulations – lotion, mousse, solution, shampoo or spray gel. These products need to be applied thoroughly to cover all of the hair. Point out to customers any cautions relating to slippery surfaces or whether they may be flammable. OTC brands include Hedrin, Lyclear, Full Marks Solution and Vamousse.

2. Chemical insecticides

These products contain chemicals that kill head lice, such as malathion (the active ingredient in Derbac-M). However, head lice have been known to develop resistance to them. As with all head lice treatments, customers should follow the manufacturer’s instructions carefully and repeat the application after seven days if indicated.