Pubic lice

  • Definition
    • Pubic lice are tiny insects that infect the pubic hair area and lay eggs there. 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 found mostly in teenagers. The lice are often spread during sexual activity.

      Rarely, pubic lice can spread through contact with objects such as toilet seats, sheets, blankets, or bathing suits (that you may try on 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 cause 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 to 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
    • Your health care provider will do an exam to look for:

      • Small gray-white oval eggs (nits) attached to the hair shafts in the outer genital area. Adult lice may also be present.
      • Scratch marks or signs of a skin infection.

      Because pubic lice may cause an eye infection in young children, eyelashes should be looked at with a high-powered magnifying glass.

      Adult lice are easy to identify under a 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

      Pubic lice are often treated with medicines that contain a substance called permethrin. To use this medicine:

      • Thoroughly work the medicine into your pubic hair and surrounding area. Leave it on for at least 5 to 10 minutes, or as directed by your health care provider.
      • Rinse well.
      • Comb your pubic hair with a fine-toothed comb to remove eggs (nits). Applying vinegar to pubic hair before combing may help loosen the 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.


      While you are treating pubic lice:

      • Wash all clothing and bedding in hot water.
      • Spray items that cannot be washed with a medicated spray that you can buy at the store. You can also seal items in plastic bags for 10 to 14 days to smother the lice.
      • Makes sure anyone with whom you have had sexual contact or shared a bed is 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: Elsevier Mosby; 2012:chap 84.

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