Head lice are tiny wingless insects that live in human hair. They are common, particularly in children.
Head lice are grey-brown in colour, the size of a pinhead when hatched and of a sesame seed when fully grown.
They cannot fly, jump or swim and are spread by head-to-head contact, climbing from the hair of an infected person to the hair of someone else.
A head lice infestation is not the result of dirty hair or poor hygiene. Head lice can affect all types of hair irrespective of its condition and length.
Head lice only affect humans and cannot be passed on to animals or be caught from them.
Life cycle of head lice
A female head louse lays eggs by cementing them to hairs (often close to the root) where they are kept warm by the scalp. The eggs are pinhead size and difficult to see.
After 7-10 days, the baby lice hatch and the empty eggshells remain glued in place. These remains are known as nits. Nits glisten white and become more noticeable as the hair grows and carries them away from the scalp.
Head lice feed by biting the scalp and feeding on blood. They take 6-10 days to become fully grown. Once mature, a head louse can crawl from head to head.
A female head louse may start to lay eggs as early as seven days after she has hatched. So to break the cycle and stop them spreading, they need to be removed within seven days of hatching.
How to spot head lice
In most cases, itching is the main symptom of head lice. It is not caused by the lice biting the scalp but by an allergy to the lice. However, not everyone experiences itching.
It's not always easy to see head lice so detection combing is the best way of finding head lice. This involves using a special fine-toothed head lice comb (with tooth spacing of less than 0.3mm to trap the smallest lice) to comb through the hair. It works better on wet hair but can be used on dry hair.
Detection combs are available from pharmacies.
Treating head lice
Head lice can usually be effectively treated using medicated lotions or by wet combing, using a specially designed head lice comb.
Wet combing can be used without medicated lotions, but needs to be done regularly and can take a long time to do thoroughly.
Medicated lotion or spray can be used as an alternative. However, no medicated treatment is 100% effective. Your pharmacist will be able to recommend an over-the-counter lotion or spray.
Preventing head lice
It's difficult to prevent a head lice infestation. Regular detection combing - for example, on a weekly basis, is the best way to find new lice quickly.
Medicated lotions and sprays do not prevent head lice infestations and should only be used if a live louse has been found on yours or your child’s head.
Image of head lice