Lice never willingly leave the head; they stay close to the scalp for food, shelter, warmth and moisture. They are most often found behind the ears and at the back of the neck. Hatched eggshells (nits) may be confused with dandruff.

The mature louse is the size of a sesame seed and has six legs and hook-like claws that grasp the strand of hair tightly, making it difficult to dislodge. It feeds on the host's blood every three to six hours, which can cause scalp itching, though most cases are asymptomatic. The diagnosis of lice infestation can be made definitively only if living lice are present.

Here's how to remove lice by combing:

• First comb through wet hair with an ordinary comb to get rid of knots and tangles.
• Apply conditioner to make it easier to comb the hair with the fine-toothed comb. Alternatively, one can use olive oil, or better yet essential oils that have been shown to treat head lice.
• Comb through every bit of hair, pulling the comb from the scalp to the hair ends. If you find lice, rinse them off the comb and down the sink. Work through the hair until you've gone through it at least twice, flushing away any lice you find. Afterward, rinse the conditioner out (or shampoo out any oil).
• Do this every three or four days to make sure that you catch any new lice that have hatched since you last combed the hair.
• Keep doing the combing until you no longer find any lice for at least two treatments in a row.

Common Misconceptions

• There is no evidence to support the cleaning of sheets and clothing, or the treating of earphones, baseball helmets, and furniture with insecticide sprays.
• Infection is spread between people only by relatively prolonged head to head contact; thus it is typically spread between people who know each other well. Lice seen on chairs, pillows, and hats are dead, sick, or elderly or are cast skins of lice--these cannot infect a person.
• School-based "no-nits" policies (banning children with nits until all nits are removed) do not make sense--less than 20 percent of school children with nits will go on to develop infestation within 14 days. About half of children sent home for head lice don't have them. Many public health experts believe that "no-nits" policies should be abandoned.
• Treatment should not be started unless live lice are found. Nits are not a sign of active infestation with head lice.
• Cutting hair, or tying it back, is not helpful and may increase the incidence of infestation by making it easier for lice to move off of and on to the scalp.
• Head lice are probably more common in girls because girls are more likely to have close contacts during play--not because they have longer hair.
• Head lice are harmless. If detached from their host they are vulnerable and effectively dead.

British Medical Journal June 7, 2003;326:1256-1257 (Free Full Text Article)