Head lice

​General information

The head louse is a human parasite a couple of millimetres in size, which feeds on human blood. Head lice live in the hair and are typically found behind the ears and on the neck. The louse itself is difficult to see, but their eggs (nits) are quite visibly attached to the hair near the scalp.

Head lice multiply fast. A female louse can lay a hundred eggs during her lifetime (one month) and the eggs hatch within 10 days from laying. The white eggshell can stay in the hair for months.

The bites can sometimes be very itchy. Scratching may lead to infection and cause burning, redness, swelling and tenderness. Sometimes there are no symptoms.

Head lice cause epidemics at schools, nurseries and care facilities. They spread easily through contact and shared combs and hairbrushes as well as bed linen and furnishings. In the autumn and winter, they spread, particularly through hats and scarfs. Head lice have nothing to do with dirty hair or poor hygiene and frequent shampooing does not prevent them from spreading.


The best treatment is to reduce the risk of spreading. Use a fine-toothed comb to find lice and eggs. Comb through the hair systematically twice over. Only those who have lice are treated, but the hair of all family members should be checked.

Pharmacies sell anti-lice treatment shampoos; follow the instructions on the package carefully. The pharmacy staff will be able to advise on the best way to use products. Comb the hair thoroughly with a fine-toothed comb before and after the shampoo treatment. Continue combing daily for two weeks. Repeat the shampoo treatments after two weeks. Take all precautionary measures: wash bedlinen and hats and scarfs.

Inform all those who are in contact with your child: the parents of their friends and the school or nursery to stop an epidemic. Keep hats and scarfs in the sleeve of the coat when left in coat racks.

When should you seek medical advice?

If the head lice don’t disappear despite your best home-care efforts, you can be prescribed medication that is taken by mouth. The medication is available on doctor’s prescription only.

This Self-care instruction has been produced in collaboration with Duodecim Terveyskirjasto

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Updated  8.6.2020