Pubic lice, also known as crab lice or crabs, are tiny, parasitic insects that feed on blood. They spread easily and cause itching and red spots.

Lice often live on the skin in the genital area, but they may be present in any area of the body with coarse hair, including the eyelashes, eyebrows, beard, mustache, and any hair on the back or abdomen.

Adult lice are gray-brown and about 1.1–1.8 millimeters long. A person may be able to see them with the naked eye. The eggs and immature lice are smaller, however, and they may not be visible without a magnifying glass.

Lice usually pass from person to person during sex, and healthcare professionals consider them a sexually transmitted infection (STI). However, close hugging and kissing can also allow them to spread, as can sharing towels and other personal items.

It is easy to pass lice to another person, especially an intimate partner.

pubic lice on some bed sheetsShare on Pinterest
Pubic lice may cause itching and red spots.

People can treat lice using over-the-counter (OTC) preparations. It is essential to follow the instructions precisely.

The Centers for Disease Control and Prevention (CDC) recommend either a 1% permethrin lotion or a mousse containing pyrethrins and piperonyl butoxide.

They note that lindane shampoo, which is a prescription medication, can kill lice and eggs, but it can be toxic to the brain and nervous system.

People should only use lindane if other treatments have not worked or if they cannot use other remedies. It is not suitable for infants and children, older people, those who are prone to seizures, individuals with skin problems, and people weighing less than 110 pounds. People should not use it during pregnancy or breastfeeding.

Other prescription treatments include malathion (Ovide) lotion 0.5% and ivermectin (Stromectol). The Food and Drug Administration (FDA) have not approved malathion for the treatment of pubic lice, and they have only approved the topical form of ivermectin, not the oral form.

The exact instructions for use will vary, but the overall process is as follows:

  1. Wash and towel dry the affected area.
  2. Saturate the affected hair with medication.
  3. Leave for as long as the instructions recommend, then remove according to the instructions.
  4. Remove the nits, or eggs, using the fingernails or a fine comb.
  5. Change into clean underwear.

If lice remain after 9 days, apply the treatment again.

In addition, people with lice should do the following:

  • Avoid sexual contact with others until the lice have gone.
  • Inform any partners or people who may have been in close contact.
  • Consider testing for other STIs.

Even if the lice appear to have gone, the person should continue treatment because if any eggs remain, they may hatch and start a new cycle. If OTC medications do not kill the lice, a doctor may prescribe a stronger lotion or shampoo.

It is important to ask a healthcare professional about treatments for lice, as options that are suitable for body hair may be harmful to use on the face.

The main symptom of pubic lice is itching, which may start about 5 days after the first contact.

A person may also notice:

  • small red bumps or spots on the skin
  • blue spots on the thighs or lower abdomen
  • dark brown or black powder — louse droppings — on the skin or in the underwear

Symptoms can affect the pubic region or any part of the body that has hair, including the eyelashes.

Will I see the lice?

An adult pubic louse is large enough to see. It has six legs, including large back legs that look like the claws of a crab. The lice use these back legs to cling onto the hair.

The eggs are yellowish-white, oval-shaped, and usually too small to see without a microscope. They stick firmly to the base of the hair.

The signs of lice may be visible in coarse hair in the pubic region, but also under the arms and elsewhere.

After treatment, empty eggshells may remain, but this does not necessarily mean that the infestation is still present.

Lice cannot jump, fly, or swim, but they can crawl.

They can move from one person to another in the following ways:

  • during any type of sexual activity
  • through nonsexual bodily contact, such as hugging or kissing, although this is less common
  • by sharing towels, bedding, and other personal items

They can also spread from one part of the body to another on the hands, for example, if a person touches their pubic hair and then their eyelashes.

Barrier protection does not prevent lice from spreading. It is the proximity of body hair that enables their transmission.

Risk factors for getting pubic lice include:

  • being sexually active
  • having more than one sex partner
  • having sexual relations with a person who has an infestation
  • sharing towels, bedding, or clothing

OTC treatment can usually remove lice and their eggs, as long as the person follows the instructions.

The person should seek medical advice if:

  • OTC medication does not kill the lice
  • lice occur during pregnancy, when treatment may not be suitable
  • a skin infection results from scratching
  • they are under 18 years of age

Without treatment, complications can arise. Pubic lice do not pass on diseases, but scratching the affected area of skin can lead to sores or a skin infection.

If lice are present in the eyelashes, there is a risk of inflammation and infection, such as conjunctivitis.

If a person is not sure whether the lice have gone, a healthcare professional can help them check.

Following treatment, if there are still moving lice or eggs that are not empty, the person should see a doctor. Stronger medication may be necessary.

Lice and eggs are easy to detect through a visual examination of the affected area. A magnifying glass may help. If there are moving lice, the person will need treatment.

The presence of eggs does not necessarily mean that there is an infestation, as some empty eggshells may remain after successful treatment.

A doctor may recommend screening for other STIs as a precaution.

Pubic lice on the eyelashes or eyebrows of children may sometimes be a sign of child abuse, according to the CDC.

People can avoid getting pubic lice or spreading them to others by:

  • seeking early treatment
  • refraining from sexual activity until the lice have gone
  • ensuring that any sexual partners also have treatment
  • refraining from sharing towels and other personal items with others
  • removing pubic and other bodily hair

After an infestation, a person should wash clothes, bed linen, sleeping bags, and towels in water of at least 130ºF and then dry them on a hot cycle for at least 20 minutes.

If there are items that the person cannot wash, they can put these into a plastic bag for 2 weeks or take them for dry cleaning.

It is not necessary to fumigate the home, but it may be a good idea to treat soft furnishings with a spray and vacuum them.

Pubic lice, or crabs, are a common problem that people can transmit through sexual contact and in other ways. The lice do not pass on diseases, but they spread easily to other people and can cause itching and distress.

Treatment is available, and people should make sure that they follow the instructions carefully. It may be a good idea for everyone in the household to receive treatment.

Products for removing pubic lice are available for purchase from pharmacies or online.