Pubic “Crab” Lice


Pubic “Crab” Lice

Pubic or “crab” lice are parasitic insects that survive by feeding on human blood. Pubic lice are different parasites than head or body lice and are usually found in the pubic hair, but can also be found in other course body hair like eyebrows, beard, chest or armpit hair. Pubic lice have forms: the egg (also called a nit), the nymph, and the adult.

Nit: Nits are lice eggs. They can be hard to see and are found firmly attached to the hair shaft. They are oval and usually yellow to white. Pubic lice nits take about 6-10 days to hatch.


Nymph: The nymph is an immature louse that hatches from the nit (egg). A nymph looks like an adult pubic louse but it is smaller. Pubic lice nymphs take about 2-3 weeks after hatching to mature into adults capable of reproducing. To live, a nymph must feed on blood.

Adult: The adult pubic louse resembles a miniature crab when viewed through a strong magnifying glass. Pubic lice have six legs; their two front legs are very large and look like the pincher claws of a crab. This is how they got the nickname “crabs.” Pubic lice are tan to greyish-white in color. Females lay nits and are usually larger than males. To live, lice must feed on blood. If the louse falls off a person, it dies within 1-2 days.

Adult pubic lice are 1.1-1.8 mm in length. Pubic lice typically are found attached to hair in the pubic area but sometimes are found on coarse hair elsewhere on the body (for example, eyebrows, eyelashes, beard, mustache, chest, armpits, etc.).

Pubic lice infestations (pthiriasis) are usually spread through sexual contact. Dogs, cats, and other pets do not play a role in the transmission of human lice.

Where Are Pubic Lice Found?

Pubic lice usually are found in the genital area on pubic hair; but they may occasionally be found on other coarse body hair, such as hair on the legs, armpits, moustache, beard, eyebrows, or eyelashes.

Pubic lice on the eyebrows or eyelashes of children may be a sign of sexual exposure or abuse. Lice found on the head is generally head lice, not pubic lice.

Note: Animals do not get or spread pubic lice.

Symptom Overview

Pubic lice can cause itching, blue spots and sores in the infected area. It may also be possible to see grey-white lice or hair nits (the egg form of pubic lice).

Get help


Prescription or over-the-counter shampoos or solutions can be used to treat pubic lice.

Warning: Do not use lice medications to get rid of lice in eyebrows and eyelashes.*
1. Wash & towel dry the infested area.
2. Carefully follow the instructions in the package or on the label. Thoroughly saturate the pubic hair and other infested areas with lice medication. Leave medication on hair for the time recommended in the instructions. After waiting the recommended time, remove the medication by following carefully the instructions on the label or in the box.
3. Following treatment, most nits will still be attached to hair shafts. Nits may be removed with fingernails, tweezers or by using a fine-toothed comb.
4. Put on clean underwear and clothing after treatment.
5. Clothing, towels & bedding: machine-wash and machine-dry those items that the infested person used during the 2-3 days before treatment. Use hot water (at least 130°F) and the hot dryer cycle.
6. Items that cannot be laundered can be dry-cleaned or stored in a sealed plastic bag for 2 weeks.
7. Inform all sex partners from within the previous month that they are at risk for infestation and should be treated.
8. Avoid sexual contact with sex partner(s) until you and your partners have been successfully treated and re-evaluated to rule out persistent infestation.
9. Repeat treatment in 9-10 days if live lice are still found.
10. Persons with pubic lice should be evaluated for other sexually transmitted diseases (STDs).

*Special instructions for treatment of lice and nits found on eyebrows or eyelashes:

1. If only a few live lice and nits are present, it may be possible to remove these with fingernails or a nit comb.
2. If additional treatment is needed for lice or nits on the eyelashes, careful application of ophthalmic-grade petrolatum ointment (only available by prescription) to the eyelid margins 2-4 times a day for 10 days is effective. Regular Vaseline* should not be used because it can irritate the eyes if applied.

Prevention of crabs

• Sexual partners should be treated at the same time as the case.
• wash bedding, all clothing including night clothes and bath towels used while infestation was present in hot, soapy water, or dry clean
• testing to exclude other sexually transmitted infections (STIs) is advisable as people infested with pubic lice will have another sexually transmitted infection.

If you suspect you might have contracted a STD, you can do a self-test quiz, the STD Quiz.

You may also chat to a facilitator on LIVE CHAT if you have more questions. The service is free and you may stay anonymous.



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