What should you know about head full of lice?

Head lice are crawling insects that live close to the scalp and feed on blood. Itching may be worse at night, but some people have little or no itch at first. Nits are eggs attached firmly to hair near the scalp; loose dandruff and product residue slide along the hair more easily.

Lice are not a sign of poor hygiene. They move most often during close head-to-head contact. Brushes, hats, pillows and headphones are less common routes, but items that recently touched an affected person's hair should not be shared until treatment advice has been followed.

Confirm live lice with a fine-toothed detection comb on wet, conditioned hair or ask a clinician to inspect the scalp. If live lice are found, follow a recommended head-lice treatment exactly, including any repeat application the product instructions require. Treat household members only when live lice are found or a clinician advises it.

Wash or isolate recently used hair items as directed, clean combs, and avoid sharing headwear. Do not use several insecticidal products together or repeat doses early. A GP consultation can help when the diagnosis is uncertain, the scalp is inflamed, or treatment has failed.

Seek medical advice for a child who is very young, a scalp with open sores or spreading redness, or symptoms that continue after correctly following treatment. Prompt assessment is sensible if there is fever, pus, painful swelling or swollen glands, because scratching can damage the skin.

Ask how to distinguish a live louse from a nit, which treatment is appropriate for the person's age, when to repeat it, and whether close contacts need checking. Mention asthma, allergies, pregnancy or previous treatment reactions.