Crab Lice

(Pubic Lice; Pediculosis Pubis)


Crabs, or pubic lice, are tiny, barely visible parasites. They are usually found in the pubic hair but can also be found in other body areas with short hair. This may include eyelashes, eyebrows, armpit hair, and mustache hair.
Pubic lice are commonly called crabs because they look like tiny crabs.
Pubic Louse
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Crab lice are parasites. Parasites are insects that need to live off of another animal. Crab lice are spread by personal contact, usually during sexual activity. Less often, crab lice may also spread by sharing personal items. This can include sharing bedding, towels, and clothing.

Risk Factors

Factors that increase your risk for crab lice include:


Symptoms include:


You will be asked about your symptoms and medical history. A physical exam will be done. Your doctor will be able to diagnose crab lice by the appearance of lice and lice eggs in your pubic area.
Your doctor may also check you for other sexually transmitted infections.


Over-the-counter shampoo or cream rinse containing permethrin or pyrethrins are used to treat pubic lice.
Some lice may be resistant to this treatment. For resistant cases, your doctor may advise:


To reduce the chance of getting crabs or spreading crabs:


American Academy of Dermatology

American College of Obstetrics and Gynecology


HealthLink BC

Health Canada


Centers for Disease Control and Prevention. Sexually Transmitted Diseases Treatment Guidelines, 2010. MMWR 2010;59(No. RR-12):1-110.

Lindane shampoo and lindane lotion. US Food and Drug Administration website. Available at: Updated June 18, 2009. Accessed May 28, 2015.

Medication guide lindane shampoo. US Food and Drug Administration website. Available at: Updated April 2002. Accessed May 28, 2015.

Parasites—lice. Centers for Disease Control and Prevention website. Available at: Updated September 24, 2013. Accessed May 28, 2015.

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