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Pubic lice

Pubic lice are tiny insects that infect the pubic hair area and lay eggs. These lice can also be found in armpit hair and eyebrows.

Crab louse, femalePubic louse-male

Alternative Names

Pediculosis - pubic lice; Lice - pubic; Crabs

Causes

Pubic lice are known as Phthirus pubis. They are found mostly in teenagers. Pubic lice are often spread during sexual activity.

Rarely, pubic lice can passed through contact with objects such as toilet seats, sheets, blankets, or bathing suits at a store.

Animals cannot spread lice to humans.

Other types of lice include:

You are at greater risk for pubic lice if you:

  • Have many sexual partners
  • Have sexual contact with an infected person
  • Share bedding or clothing with an infected person

Symptoms

Pubic lice causes itching in the area covered by pubic hair. Itching often gets worse at night. The itching may start soon after getting infected with lice, or it may not start for up to 2 - 4 weeks after contact.

Other symptoms can include:

  • Skin reaction that causes skin to turn bluish-gray in color
  • Sores in the genital area due to bites and scratching
Crab lice

Exams and Tests

The health care provider will do an exam to look for:

  • Small gray-white oval eggs (nits) attached to the hart shafts in the outer genital area. Adult lice may also be present.
  • Scratch marks or signs of an infection, such as impetigo .

Because pubic lice may cause an eye infection (blepharitis ) in young children, eyelashes should be viewed with a high-powered magnifying glass.

Adult lice may be easily identified under the microscope. Pubic lice are often referred to as "the crabs" because of their appearance.

Teenagers with pubic lice may need to be tested for other sexually transmitted infections (STIs).

Treatment

MEDICINES

Pubic lice are best treated with a prescription wash containing permethrin, such as Elimite or Kwell:

  • Thoroughly work the shampoo into dry pubic hair and surrounding area for at least 5 minutes.
  • Rinse well.
  • Comb the pubic hair with a fine-toothed comb to remove eggs (nits). Applying vinegar to pubic hair before combing may help loosen nits.

Most people need only 1 treatment. If a second treatment is needed, it should be done 4 days to 1 week later.

Over-the-counter medicines to treat lice include Rid and Nix. Malathione lotion is another option.

OTHER CARE

While you are treating pubic lice:

  • Wash all clothing and bedding in hot water.
  • Spray items that cannot be washed may be sprayed with a medicated spray that you can buy at the store. You can also seal items in plastic bags for 10 - 14 days to smother lice.
  • Makes sure anyone with whom you have had sexual contact or shared a bed be treated at the same time.

People with pubic lice should be checked for other sexually-transmitted infections when lice are discovered. 

Outlook (Prognosis)

The proper treatment, including thorough cleaning, should get rid of the lice.

Scratching can make the skin become raw, or even cause a skin infection.

When to Contact a Medical Professional

Call for an appointment with your health care provider if:

  • You or your sexual partner has symptoms of pubic lice
  • You try over-the-counter lice treatments and they are not effective
  • Your symptoms continue after treatment

Prevention

Avoid sexual or intimate contact with people you know have pubic lice until they have been treated.

Bathe or shower often and keep your bedding clean. Avoid trying on bathing suits while you are shopping. If you must try on swimwear, be sure to wear your underwear. This may prevent you from getting or spreading pubic lice.

References

Burkhart CN, Burkhart CG, Morrell DS. Infestations. In: Bolognia JL, Jorizzo JL, Schaffer JV, et al, eds. Dermatology. 3rd ed. Philadelphia, Pa: Mosby Elsevier; 2012:chap 84.

Diaz JH. Lice (pediculosis). In: Mandell GL, Bennett JE, Dolin R. Mendell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Churchill Livingstone Elsevier; 2009:chap 293.

Updated: 11/20/2012

Kevin Berman, MD, PhD, Atlanta Center for Dermatologic Disease, Atlanta, GA. Review provided by VeriMed Healthcare Network. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.


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