Head lice and nits: what the NHS says

What are head lice and nits?

Head lice are small insects that live in human hair. The NHS says they are up to 3mm long, which makes them hard to spot. Nits are the eggs that the lice lay, and they can be small brown or white specks attached to the hair.

Head lice are a common problem, but they are not a sign of poor hygiene. NHS 111 Wales says they are not caused by dirty hair. NHS inform adds that lice do not prefer any particular type of hair, whether dirty, clean, long or short.

Empty egg cases left on the hair can be hard to tell apart from dandruff, which is one reason careful checking matters. Sources differ a little on how nits are described, with NHS 111 Wales calling them brown or white and a West Yorkshire NHS page calling them the empty egg cases that lice hatch from.

What signs do head lice cause?

The NHS lists small brown or white eggs in the hair and an itchy scalp as signs of head lice. NHS inform also lists a rash on the back of the neck and a feeling that something is moving in the hair. Some people with head lice have no symptoms at all, although itching is the main symptom for many.

Itching can have other causes, so it does not prove that lice are present. Nits alone do not show that a person has an active infestation. The sources say the only certain sign is finding a live, moving louse.

How do head lice spread?

The sources describe head lice as spreading through close head-to-head contact. NHS Northern Ireland says they are very unlikely to be spread by objects such as hats, combs and pillows.

The NHS says there is no proven way to prevent head lice, but that regular combing helps to catch them early. Medicated lotions and sprays should not be used to prevent them, because they can irritate the scalp.

Because lice spread easily, the NHS advises checking other family members' hair regularly. They may need to wet comb too.

NHS Northern Ireland describes head lice as spread by direct head-to-head contact. For that reason, checking everyone in the household is part of the advice given by local NHS services.

How can someone tell for sure?

The NHS says the only way to be sure is to find live lice. This is done by combing the hair with a special fine-toothed comb, called a detection comb.

One NHS source notes that conditioner keeps the lice from moving, which makes wet combing more reliable than dry combing. Lice that have been seen to move confirm an infestation.

Nits on their own do not prove an active infestation, so the NHS advises looking for a live louse before treating. The comb is used on the whole head, working through the hair from the roots to the ends.

How does the NHS say head lice are treated?

The NHS describes wet combing as the first method to try. Hair is washed with ordinary shampoo, covered in plenty of conditioner, and combed from the roots to the ends with a fine-toothed detection comb, going through the whole head twice.

Combing is repeated on days 1, 5, 9 and 13 to catch newly hatched lice, and everyone is checked again on day 17.

If wet combing has not worked, the NHS says a medicated lotion or spray can be tried, and these can be bought from a pharmacy. Some treatments need to be repeated after a week to kill newly hatched lice.

The NHS says everyone in the household who has head lice should be treated on the same day. Washing bedding and towels on the day treatment starts is optional.

The NHS says the aim of these steps is to catch lice that hatch after the first combing session. For this reason the days are spread across about two weeks, ending with the day 17 check.

What does the NHS say does not work, and do children stay off school?

The NHS lists several products as unlikely to work. These include head lice repellents and electric combs for head lice.

The NHS says children do not need to stay off school because of head lice. It also says laundry does not need a hot wash.

The NHS guidance lists these as unlikely to work, so wet combing or a medicated lotion or spray from a pharmacy remains the route the NHS describes. Washing bedding and towels on the day treatment starts is optional.

When might a pharmacist help?

The NHS says a pharmacist can advise on the best lotion or spray when wet combing has not worked.

The NHS advises asking a pharmacist for advice if wet combing has been tried through day 17 and live lice are still present.

Medicated lotions and sprays are described by the NHS as the next step when combing has not worked. A pharmacist is the person the NHS names for advice on the choice of product.