The head louse is a tiny greyish-brown insect, about 2.5mm long. Head lice cling to hair and are usually found on the scalp. They live on blood from the host, which they get by biting through the scalp
You can part the hair and look for nits, but the lice will move quickly into hiding. The best way to search for head lice and nits is to buy a specially designed detection (nit) comb from a pharmacy. This is a fine-toothed plastic comb with spacing of less than 0.3mm.
Check every other member of the family, including any adults who have close contact with the child. You can work out when the lice first moved in by judging how many centimeters from the scalp you find the nits. Hair grows at about 1cm a month; so a nit 2cm from the scalp was laid about two months ago.
The three main treatments for head lice are listed below, but no method is 100 per cent effective.
Insecticides that kill head lice are available in lotion, mousse and shampoo form. You can buy them from the pharmacy or get them on prescription.
These are relatively new products that work in a different way to conventional insecticides for head lice. There are currently three available:
Hedrin lotion (containing dimeticone)
Itax lotion (containing cyclomethicone)
NYDA pump spray (containing dimeticone).
Instead of poisoning the parasites by chemical means, these products kill the lice by physically coating their surfaces and smothering them. As these products work in this physical way, head lice cannot become resistant to them.
Wet combing removes lice without using chemicals. It involves wetting the hair, applying conditioner, then combing it with a fine-toothed comb for at least 30 minutes every third or fourth day over a two-week period.
http://www.netdoctor.co.uk/diseases/facts/lice.htm
http://www.bbc.co.uk/health/physical_health/conditions/heartburn1.shtml