Pubic Lice Or Crab Lice


What Is It?

Pubic lice or crab lice are tiny insects that infest a person’s pubic hair, although they also can be found on facial hair, armpit hair and eyelashes. The insects look like crabs, and a person with these lice often is said to have “crabs.” Their front claws enable them to grasp hairs so they can both move around and remain with their human host. Crab lice, like all lice, feed on their host’s blood. Female lice produce eggs, which are cemented to the hair shaft close to the skin. It takes about seven to 10 days for an egg to hatch. Most people who are infested with crab lice will have about a dozen active lice on them at any one time.


Crab lice usually cause intense itching. There also may be tiny red or blue marks where the insect has been biting, and the eggs, or nits, may be seen attached to the pubic hair close to the skin. Sometimes, more severe reactions occur, such as the development of pustules or intense skin reactions where the insects have been feeding.


Diagnosing a crab-lice infestation is easy, because the insects can be identified easily, and the nits can be seen attached to the base of the hair. Since most crab-lice infestations are transmitted through sexual activity, anyone who has crab lice also should be screened for other sexually transmitted diseases. Several studies have found that many people infested with crab lice also will have another sexually transmitted disease. In addition, the sexual partners of someone diagnosed with crab lice infestation should be notified.

Although most crab-lice infestations are transmitted through sexual contact, it is possible to get infested with the insects by sharing a bed with an infested person. Crab lice can live for about 24 hours off of a human host.

Expected Duration

Crab-lice infestations can persist indefinitely if they’re not treated. With treatment, the infestation is usually eliminated immediately.


To avoid getting crab lice, avoid sexual partners who are infested, and avoiding sharing a bed with an infested person.


Crab-lice infestations usually are treated by applying a créme rinse containing 1-percent permethrin to the pubic hair and leaving it in place for 10 minutes. Also effective are rinses containing 1-percent lindane or pyrethrins with piperonyl butoxide. Women who are pregnant or lactating should not use lindane. Nits can be removed using a fine-toothed comb after treatment. Clothing and bedding that the infested person used in the two to three days before treatment should be washed in hot water and dried in a clothes dryer on a high-heat setting.

When To Call A Professional

Although products to treat crab-lice infestations are available over-the-counter, it is a good idea to consult your health-care provider if you suspect you may be infested because you also may have another sexually transmitted diseases. You also should consult someone if your symptoms are especially severe, and should follow up with your health-care provider to be sure the infestation has been treated successfully.


Crab-lice infestations respond well to treatment and are not associated with any lasting symptoms.

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.