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Head Lice: Wet Combing, Treatments, and Why They Keep Coming Back

By the Lyng Pharmacy team · Based on NHS and BNF guidance · August 2026 · 3 min read
Fine-toothed detection comb being drawn through a child’s wet hair
Wet combing with conditioner and a detection comb is both the most reliable way to check and a treatment in its own right.

Head lice are miserable, mildly embarrassing and completely harmless. They do not carry disease, they are not a sign of dirty hair, and they cannot jump or fly. Almost every failed treatment comes down to one of two things: treating when there were never live lice there, or not repeating the treatment seven days later.

Check properly before treating anything

Only treat if you find a living, moving louse. Eggs and empty shells stuck to hair are not proof of an active infestation — they can stay glued there for months after the lice have gone.

The reliable method is detection combing. Wash the hair, apply plenty of conditioner without rinsing, and comb through section by section with a fine-toothed detection comb from roots to tips, wiping the comb on kitchen paper after each stroke. Check the paper as you go. Do the whole head, then rinse.

Itching is an unreliable guide. It comes from an allergic reaction and can take weeks to develop, or not appear at all.

The two things that work

Wet combing, done properly, clears lice without any chemicals. Comb as described above on days 1, 5, 9 and 13, and then check again on day 17. The schedule matters — it is designed to catch newly hatched lice before they are old enough to lay eggs.

Physical insecticides such as dimeticone and other silicone-based lotions coat and suffocate the lice. They are not affected by insecticide resistance, which is why they have largely replaced older treatments, and are generally suitable for children over six months, in pregnancy and while breastfeeding — check the individual product.

Whichever you choose, repeat after seven days. No treatment kills all the eggs, so a second application catches the lice that hatched after the first. Skipping the second treatment is the single most common reason head lice appear to come back.

What does not help

There is no evidence for treating the whole household preventively, using electronic combs, tea tree oil, mayonnaise, or leaving products on overnight when the instructions do not say to. Nor is there any need to boil bedding, bag up soft toys or fumigate the house — lice die within a day or so off the head.

Check everyone in the household on the same day and treat only those with live lice. Tell close contacts and the school so others can check too.

School and everyday life

Children do not need to stay off school for head lice. Long hair tied back reduces head-to-head contact, which is essentially the only way lice spread. Combs, brushes and hats are a very unlikely route.

If you have treated twice, seven days apart, and are still finding live lice, come and speak to us — it usually means a step in the routine has slipped rather than that the treatment has failed.

Head lice that will not shift?

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Frequently asked questions

How do I know if my child really has head lice?
Only a living, moving louse confirms it. Eggs stuck to hair can remain for months after the lice have gone. Use conditioner and a fine detection comb to check properly.
Why do head lice keep coming back?
Usually because the treatment was not repeated after seven days. No treatment kills all the eggs, so a second application is needed to catch newly hatched lice.
Does my child need to stay off school with head lice?
No. Head lice are not a reason to miss school. Tell the school so other families can check, and tie long hair back.
Do I need to wash all the bedding?
No. Lice die within about a day off the head, so there is no need to boil bedding, bag toys or treat the house.

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