How to tell if you have head lice
Only 1 in 3 people with head lice experiences itching. It is worse behind the ears and at the back of the neck. Itching is caused by an allergy to the saliva of the louse, and it may be several weeks before it occurs.
Seeing the lice
A better method uses a ‘lice comb’ (a special comb with narrow-spaced teeth), which you can buy from a pharmacy. Wash the hair, leave it damp and comb out tangles with an ordinary comb. Rub some ordinary conditioner into the hair. Then divide the hair into sections and carefully comb each section with the lice comb, starting at the scalp. Every now and again, wipe the comb on a tissue and look closely for live lice. This works better than the dry hair method, because lice stay very still when hair is wet, so they can be combed out.
If you have Afro-Caribbean hair, do not bother with a lice comb – it will be too uncomfortable. Instead, use lots of conditioner and an ordinary comb.
Look for nits
Look for black specks
Look for bites
For more information, see our sections on how head lice can be caught and how to treat head lice, or read Dr Phil Hammond's light-hearted poem on head lice. If your scalp is itching but you cannot find any head lice, see our pages on itching and dandruff.
Written by: Dr Margaret Stearn
Edited by: Dr Margaret Stearn
Last updated: Monday, March 7th 2011
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In the UK, each month 20% of hairdressing salons see head lice in a client's hair
An estimated 5% of the UK population has head lice
Each year in the UK, the NHS and the general public together spend £29 million on head lice treatments
'Lousy', 'nitwit', 'nit-picking', 'nitty-gritty', 'go through something with a fine-tooth comb' - all these phrases come from lice
The average person with head lice has about 20 lice. During their 30-day life, 20 lice will lay 2652 eggs (Lancet 2003;361:99-100)
After mating, a female head louse keeps spare sperm in a special container in her body (spermatotheca), so that she does not have to bother with mating again, but can use the sperm she has kept (Lancet 2003;361:99-100)
Head lice are fairly speedy. They can move at 23 cm per minute (Lancet 2003;361:99-100)
Head lice have probably been annoying humans for at least 72 000 years (New Scientist 2003;23 Aug)