Pubic lice

Pubic lice are tiny parasitic insects that live in coarse human body hair. The medical name for the louse is Pthirus pubis. They are often called “crabs” because their short, broad bodies and large front claws resemble a crab.

Pubic lice most often live in pubic hair around the genitals. They can also affect hair around the anus, underarms, chest, abdomen, beard or moustache. Occasionally, they infest eyebrows or eyelashes. They do not usually live in scalp hair.

The lice feed on small amounts of blood from the skin. Their bites and saliva can cause itching and irritation. They do not burrow under the skin.

Pubic lice are usually spread through close body contact, most often sexual contact. They are considered a sexually transmitted infestation, although sexual intercourse is not required for them to spread. Less commonly, they may spread through recently shared clothing, bedding or towels.

Having pubic lice is not a sign of poor hygiene. Washing more often does not prevent them, and anyone with close exposure can become infested.

Pubic lice are treatable and do not usually cause serious health problems. Treatment also needs to address recent sexual partners and potentially contaminated clothing or bedding. Otherwise, the lice can return.

Itching in the affected area is the most common symptom. It may become more noticeable at night. Some people have little or no itching, especially early in the infestation.

Other possible signs include:

• Tiny tan or grey-brown lice moving among coarse hairs
• Pale eggs, called nits, firmly attached near the base of hairs
• Red bumps, scratch marks or irritated skin
• Small blue-grey spots where lice have fed
• Dark specks in underwear from louse droppings or small spots of blood

Adult pubic lice are about the size of a sesame seed and can be difficult to see. Nits are smaller. Unlike loose flakes of skin, nits are stuck to the hair shaft and do not brush away easily.

Symptoms may not begin immediately after exposure. This means you may pass lice to someone else before realizing they are present.

Lice on the eyelashes can cause itching, crusting and red or swollen eyelids. This is called blepharitis, meaning inflammation of the eyelid edges. Children with lice around the eyelashes or eyebrows need medical assessment because the source of exposure must be carefully considered.

Pubic lice cannot fly or jump. They crawl from one person’s hair to another during close contact. Sexual contact is the most common way they spread because pubic hair and nearby skin remain in close contact.

Risk is higher if you:

• Have close physical or sexual contact with someone who has pubic lice
• Share a bed, clothing or towels with an affected person
• Have sexual partners who have not yet been treated
• Resume close contact before treatment has worked

Pubic lice only live on humans. Pets do not carry or spread them.

Transmission from toilet seats is considered very unlikely. Lice do not survive well away from a human host, and they cannot grip smooth surfaces easily.

Condoms help prevent many sexually transmitted infections, but they do not fully protect against pubic lice. Lice can spread between areas of hair or skin that a condom does not cover.

Pubic lice are confirmed by finding a live louse or viable-looking eggs attached to coarse body hair. A healthcare professional may inspect the area under a bright light and use a magnifying lens or dermatoscope, which is a handheld tool for examining skin and hair.

Empty eggs can remain attached after treatment. Finding nits alone does not always mean there is an active infestation. Live moving lice provide clearer evidence.

Other conditions can cause similar itching, including eczema, fungal infections, scabies and irritation from skin products. Loose flakes from dandruff or dried skin may also be mistaken for eggs.

Because pubic lice commonly spread during sexual contact, testing for other sexually transmitted infections may be offered. Pubic lice do not cause these infections, but the same contact may have created an opportunity for exposure.

Pubic lice are treated with insect-killing products designed for use on human skin. Common options include products containing permethrin or pyrethrins with piperonyl butoxide. Which product is suitable depends on factors such as pregnancy, breastfeeding, age, allergies, the area affected and whether earlier treatment worked.

Follow the product instructions exactly. Using more product or leaving it on longer than directed does not make it safer or more effective. Do not use household insecticides, garden pesticides, kerosene or veterinary flea treatments on your body.

Apply treatment to every affected hair-bearing area specified in the instructions, not only the spot that itches most. Some products do not kill every egg, so another treatment may be needed if live lice are found later. A pharmacist or healthcare professional can advise if the first treatment does not work.

A fine-toothed comb or fingernails can be used to remove attached nits after treatment. Removing every empty egg is not always necessary for cure, but it can make checking for new lice easier.

Pubic lice on eyelashes need clinician-guided, eye-safe treatment. Ordinary lice products must not be applied near the eyes. Seek medical advice rather than trying to remove lice from the eyelids with chemicals or sharp tools.

Clothing, towels and bedding used during the infestation should be machine-washed and dried using hot settings appropriate for the fabric. Items that cannot be washed can be dry-cleaned or sealed in a closed plastic bag for two weeks.

Tell current sexual partners and partners from the previous month so they can be checked and treated. Avoid sexual or close body contact until you and your partner or partners have completed treatment and no live lice remain.

Shaving pubic hair may remove some lice or eggs, but it is not a reliable treatment. Lice may remain on other coarse body hair.

Complications are uncommon. Repeated scratching can break the skin and allow bacteria to cause an infection. Signs include increasing pain, warmth, swelling, pus or redness that continues to spread.

Lice around the eyelashes may cause ongoing eyelid inflammation or irritation of the eye’s surface. Severe eye pain or changes in vision are not typical and need prompt assessment.

Some people develop skin irritation from a lice treatment. Mild temporary stinging may occur, but marked swelling, blistering or breathing difficulty needs medical attention.

Treatment can fail if it is not used as directed, if some affected areas are missed, or if close contacts remain untreated. In some places, lice may also be resistant to certain products. This means the product no longer kills them reliably. Persistent live lice should be assessed rather than repeatedly treated with the same product.

Pubic lice are not known to transmit infections through their bites.

There is no medicine or skin product that prevents pubic lice before exposure.

The most effective prevention is avoiding close physical or sexual contact with someone who has an active infestation until treatment is complete. Do not share bedding, towels or clothing with an affected person until those items have been cleaned.

Condoms remain important for reducing the risk of many sexually transmitted infections and pregnancy, but they cannot fully prevent pubic lice because uncovered hair and skin can touch.

If you are diagnosed, prompt treatment and notifying recent partners can reduce further spread and reinfestation. Routine insecticide spraying of furniture or the home is not needed.

Most infestations clear after correct treatment and management of close contacts. Itching may continue for several days even when the lice have been killed because the skin remains irritated. Continuing itch alone does not prove that treatment failed.

Check the affected hair during the week after treatment. The important sign is whether live, moving lice remain. Eggs or empty shells may stay attached to hairs for longer.

If live lice are still present, treatment may need to be repeated or changed with advice from a pharmacist or healthcare professional. Repeated exposure from an untreated partner can also cause the infestation to return.

Pubic lice do not become a chronic condition once the lice and eggs are cleared. They do not remain dormant inside the body. However, you can become infested again after a new exposure.

The diagnosis can feel embarrassing or create tension with a partner. Pubic lice do not show when exposure occurred, and symptoms may take time to appear. Their presence does not by itself prove that a partner has recently been unfaithful.

Arrange routine medical or pharmacy advice if:

• You are unsure whether you have pubic lice
• Treatment has not removed the live lice
• You are pregnant, breastfeeding or treating a young child
• Lice or eggs are present on eyebrows or eyelashes
• The skin is becoming increasingly sore, swollen or discharging pus
• You want testing for other sexually transmitted infections
• You may have reacted to a treatment product

A child with pubic lice, particularly on the eyelashes or eyebrows, should be medically assessed. Pubic lice can occasionally spread through shared household items, but healthcare professionals must also consider whether inappropriate sexual contact could have occurred.

Seek urgent medical help for severe eye pain, marked eye swelling or a change in vision.

Call emergency services for signs of a severe allergic reaction after treatment, such as difficulty breathing, swelling of the tongue or throat, collapse or severe dizziness.

Are pubic lice the same as head lice?

No. Pubic lice and head lice are different insects. Pubic lice are adapted to coarse body hair and do not usually infest the scalp. Head-lice products may also have different instructions, so use a treatment specifically recommended for the affected area.

Can pubic lice jump or fly?

No. They can only crawl. Spread usually requires close contact between affected hair and another person’s hair or skin.

Can I catch pubic lice from a toilet seat?

This is very unlikely. Pubic lice do not survive well away from the body and cannot grip a smooth toilet seat easily. Close body contact is a much more common cause.

Will shaving get rid of pubic lice?

Not reliably. Shaving may remove some affected hairs, but lice or eggs can remain elsewhere, including the underarms, chest, abdomen or anal area. An appropriate lice treatment is still needed.

How do I know whether treatment worked?

Look for live, moving lice during the following week. Itching and attached empty eggs may continue after successful treatment. If live lice remain, ask a pharmacist or healthcare professional about retreatment or another option.

Can I have sex after treatment?

Wait until you and any affected partners have completed treatment and no live lice remain. Otherwise, the lice may pass back and forth. Consider testing for other sexually transmitted infections as well.