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Pubic lice: Crabs

Pubic lice are commonly known as 'crabs' or crab lice. They are tiny parasites that live in coarse human body hair, such as pubic hair.

Pubic lice spread via close contact with another person's body, often during sex. However, public lice can spread through sharing clothes, towels or bedding.

Pubic lice do not spread sexually transmitted infections (STIs), but if a person has crabs, they may be advised to be tested for STIs as well.

Symptoms of pubic lice

Adult public lice are around 2mm long and yellowy-grey or dusky red. They lay eggs which they attach to the base of hairs.

After being infected with pubic lice, symptoms may not appear for around five days to several weeks.

The symptoms include:

  • Itching, inflammation or irritation in affected areas often made worse by scratching
  • Black powder or tiny blood spots on underwear or skin
  • Blue spots around affected areas from lice bites

Home treatment for pubic lice

The following treatments are most often used to treat public lice:

  • Malathion 0.5% aqueous lotion
  • Permethrin 5% dermal cream

Guidelines recommend applying the treatment to the whole body, including beard and moustache, pubic hair and hair near the anus because the lice can spread. Do not apply to the face, hair on the scalp, eyebrows or eyelashes. Avoid contact with the eyes - if contact occurs, thoroughly rinse the eyes with water.

Make sure the skin is clean and dry before applying the treatment

Follow the packet recommendations for how long to leave the treatment on before washing it off (malathion - 12 hours or overnight, permethrin - 24 hours). If you need to wash any part of the body being treated, reapply the treatment afterwards.

Repeat the treatment after three to seven days as per instructions.

Those under the age of 18, and pregnant and breast-feeding women should seek medical advice before using over the counter treatment for pubic lice.

Use over-the-counter antihistamines for itching.

If symptoms persist

If you think you have lice in your eyelashes, see your doctor, who can recommend an eye ointment.

If symptoms persist after a second treatment, seek medical advice as lice can build up a resistance to a particular treatment. Not all people who have lice have symptoms, so it's important that you let others that have been in close contact with you know that they should examine themselves for lice.

To prevent re-infestation all close contacts, including household and sexual contacts, should be treated at the same time even if they do not have symptoms.

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WebMD Medical Reference

Medically Reviewed by Dr Rob Hicks on November 20, 2012

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