Diagnosis

During an examination, your doctor may use a magnifying lens to look for lice. Your doctor may also use a special light, called a Wood's light, to check for nits. This special light makes the nits easier to spot by making them look pale blue.

Head lice

A diagnosis of head lice can be made after a live young or adult louse in the hair or on the scalp is found, or after one or more nits are seen on hair shafts located within 1/4 inch (6.4 millimeters) of the scalp.

If you don't see any live lice or you see nits that are more than 1/4 inch away from the scalp, the infestation is probably no longer active. Nits should be removed to prevent a recurrence.

Body lice

A diagnosis of body lice may be made if eggs or crawling lice are found in the seams of clothing or on bedding. It's possible to see a body louse on skin if it crawls there to feed.

Pubic lice

Pubic lice are diagnosed when moving lice or nits are seen on hair in the pubic area or on other areas of coarse hair, such as chest hair, eyebrows or eyelashes.