Pubic lice

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at February 8, 2016
StartDiseasesPubic lice

Pubic lice are tiny insects that are commonly found in the genitalia of a person. These tiny insects have bodies that resemble crabs and thus a nickname for pubic lice is crabs. Their infestation in the genitalia is considered a sexually transmitted disease (STD).


Definition & Facts

Pubic lice are small insects that actually look like tiny crabs. In fact, they measure 1/16 of an inch or less in size. They are different from the head lice and can be identified by their round shape and the fact that they appear to have claws as their back legs. They infest the hair on the human body, most commonly in the genital area.

These tiny insects live by feeding on human blood, feeding four to five times per day. The lice lay eggs and multiply rapidly. They take between 16-25 days to cycle from egg to adult and then the adults can live another 30 days. Humans are the only known host for this parasite and transmission occurs primarily through sexual contact.

Symptoms & Complaints

The main symptom of pubic lice is severe itching, especially in the genital area. This itching occurs because humans are sensitive to the louse saliva that gets on their skin. The itching may not happen immediately. In fact, there may be no symptoms that you have pubic lice at first. It may take up to two weeks to four weeks after becoming infested until symptoms begin and become severe. Itching is often worse at night.

Additionally, the area around the feeding sites of the lice may turn a blue-gray color that may last for several days. One may also have sores in the infected skin. These are caused by the bites or by scratching.

Other areas with sparse, course hair may also be affected by pubic lice though it is less common. These areas can include the legs, the chest, the armpits, a beard or mustache, or eyebrows and eye lashes. It is unlikely to find pubic lice in the finer hair of the scalp.

Pubic lice are most commonly found in the eyebrows and eye lashes of children and may indicate sexual abuse. Children can, however, catch pubic lice in their facial hair from clothing, linens, or towels that have been shared with an infected person.


Pubic lice are caused when the lice come in contact with your skin or hair. Since the lice cannot jump or fly, there must be close contact. These pubic lice are most often spread by the intimate contact of sexual intercourse. It is possible, however to become infected from sharing clothing, beds or bed linens, towels, or closets with another person.

Occasionally, it is spread when trying on close fitting clothing at a store, like underwear or bathing suits. Animals cannot spread pubic lice to humans since the pubic lice do not use animals as their hosts.

Diagnosis & Tests

One can usually diagnose pubic lice on their own. If one thinks they have them, carefully checking the pubic hair to find an insect is key. If one cannot see the lice, a magnifying glass may help. The lice are usually a pale blue color though sometimes they turn darker after drinking blood. The presence of moving lice confirms diagnosis. Lice eggs are another indicator of a lice infestation. The eggs are tiny and white. They are usually found by the root of the pubic hair.

Lice eggs can be present but dead, especially after treatment. They can be removed with a fine toothed comb or with fingernails. A doctor may be needed for diagnosis if you cannot see any lice but still have itching.

Additionally, discolored skin or skin infected by insect bites or by scratching may need to be treated by a doctor. If you are unsure of the diagnosis, see a doctor for confirmation and treatment instructions. If one has tried treatment and still finds live lice, a doctor may also be necessary to provide further treatment.

Treatment & Therapy

Pubic lice is most often treated by a louse killing lotion or gel. These can be obtained over the counter or by prescription from your doctor. An over the counter product containing 1% permethrin or a mousse containing pyrethrins and piperonyl butoxide is recommended for initial treatments. It can be found at most drug stores. This product is safe if it is used exactly according to the package instructions. Treatment can be reapplied in about 10 days if live lice still appear on the body.

Another product, lindane, is a prescription medication shampoo that can be obtained from a pharmacy. It can kill the lice and the lice eggs. It can be toxic to the brain and nervous system, however, and it should not be used as a first choice medication. It also should not be used by children or certain other groups of people such as those with seizure conditions, pregnant women, or in people with certain other conditions. Your doctor will determine if it is necessary for you to use this medication and discuss the potential risks with you.

To treat pubic lice that are in the eyebrows or eye lashes, one can often simply remove them with a fingernail or nit comb. If that is not possible, an ophthalmic grade petrolatum, available only by prescription, should be applied several times daily for 10 days until no live lice are seen.

Prevention & Prophylaxis

The best way to prevent pubic lice is to be sure that one’s sexual partner is not infested with pubic lice. If one does have pubic lice, one can prevent the further spread of the infection by informing all recent sexual partners of the condition, advising them to get checked and treated, if necessary. One should also avoid all further sexual contact with any partner until one is sure that the lice are gone.

Additionally, all clothing, bed linens, and towels should be washed in hot water (130F) in the washing machine and dried on hot in a clothes dryer. If one cannot wash certain items, they can be dry cleaned. Yet another alternative is to seal the items in a plastic bag for two weeks. Then be careful not share clothing, bedding or towels with people who have a pubic lice infestation.