Mayo Clinic Health Library

Pubic lice (crabs)

Updated: 12-14-2012

Definition

Pubic lice, commonly called crabs, are tiny insects found in your genital area. They are a different type of louse from head lice and body lice. Measuring 1/16 inch (1.6 millimeters) or less, pubic lice received their nickname because their bodies resemble sea crabs.

The most common way to acquire pubic lice is through sexual intercourse. In children, pubic lice may be found in the eyebrows or eyelashes and can be a sign of sexual abuse. However, children can sometimes catch pubic lice from heavily infested parents simply by sharing a communal bed.

Pubic lice feed on your blood, and their bites can cause severe itching. Treatment includes applying over-the-counter creams and lotions that kill the parasites and their eggs.

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Symptoms

If you have pubic lice (crabs), you may experience intense itching in your genital region. Pubic lice don't infest the scalp, but they can spread to other areas with coarse body hair, including the:

  • Legs
  • Chest
  • Armpits
  • Beard or mustache
  • Eyelashes or eyebrows, more commonly in children

When to see a doctor
Seek medical advice about pubic lice treatment if:

  • Over-the-counter products don't kill the lice
  • You're pregnant
  • You have any infected skin abrasions from scratching
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Causes

Pubic lice are most commonly transmitted during sexual activity. Although it's unusual, you may also acquire pubic lice from contaminated sheets, blankets, towels or clothes.

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Risk factors

People who have other sexually transmitted infections are more likely to also have pubic lice.

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Complications

Pubic lice infestations can usually be treated with a louse-killing lotion or gel. However, a pubic lice infestation sometimes leads to complications such as:

  • Discolored skin. Pale blue spots may develop where pubic lice have been feeding continually.
  • Secondary infections. If itchy lice bites cause you to scratch yourself raw, these wounds can become infected.
  • Eye irritations. Children who have pubic lice on their eyelashes may develop a type of pink eye (conjunctivitis).
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Preparing for your appointment

If you can't get rid of pubic lice on your own, you may need to talk to your family doctor.

What you can do
Before the appointment, you may want to write a list that answers the following questions:

  • How long have you had pubic lice?
  • What symptoms are you experiencing?
  • How did you become infested?
  • Have you spread the infestation to others?
  • What treatments have you tried?
  • Do you have any chronic health problems?
  • What types of medications or supplements do you take?

What to expect from your doctor
During the physical exam, your doctor will check your genital area for signs of live lice or viable lice eggs (nits).

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Tests and diagnosis

You or your doctor can usually confirm a pubic lice infestation through a visual examination of your pubic area. The presence of moving lice confirms infestation.

Lice eggs (nits) also may indicate an infestation. However, nits can cling to hairs and be present, although no longer alive, even after successful treatment.

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Treatments and drugs

If over-the-counter lotions or shampoos (Nix, Rid, others) don't kill your pubic lice, your doctor may prescribe stronger treatments, such as:

  • Malathion (Ovide). You apply this prescription lotion to the affected area and wash it off after eight to 12 hours.
  • Ivermectin (Stromectol). This medication is taken as a single dose of two pills, with an option to take another dose in 10 days if the treatment isn't initially successful.
  • Lindane. Because of its toxicity, lindane is usually prescribed only when other treatments fail. You apply lindane to the affected area and wash it off after four minutes. It's not recommend for women who are pregnant or breast-feeding, or for children younger than age 2.
  • Eye treatments. If pubic lice are found in eyelashes, you can treat them by applying petroleum jelly to your eyelid and lashes three times a day for several days. In addition, or as an alternative, the lice and nits can be gently removed from eyelashes using tweezers, a nit comb or your fingernails. Your doctor may also prescribe a medicine to apply to the eyelids.
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Lifestyle and home remedies

You can get rid of pubic lice with a patient, thorough approach that involves cleaning yourself and any personal belongings that may be contaminated.

These steps may help you eliminate lice infestations:

  • Use lotions and shampoos. Choose from among several over-the-counter lotions and shampoos (Nix, Rid, others) designed to kill lice. Apply the product according to instructions. You may need to repeat treatment in seven to 10 days.
  • Wash contaminated items. Wash bedding, clothing and towels used in the two days prior to treatment with hot, soapy water — at least 130 F (54 C) — and dry them at high heat for at least 20 minutes.
  • Dry-clean or seal unwashable items. If you can't wash an item, have it dry-cleaned or place it in an airtight bag for two weeks.
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Prevention

To prevent pubic lice infestation, avoid having sexual contact or sharing bedding or clothing with anyone who has an infestation. If you are being treated for pubic lice, all sexual partners must also be treated.

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