Pubic Lice: Symptoms, Diagnosis, and Treatment

Similar to both head lice and body lice, pubic lice (also known as crabs or crab lice) are flat, wingless, parasitic insects that feed of off blood to survive. Pubic lice (Pthirus pubis) don’t fly or hop, and are primarily found in the pubic or genital area of humans. But at times, pubic lice have also taken up residence in other areas of coarse body hair, such as mustaches, beards, armpits, and eyebrows.

It’s important to note that pubic lice on the eyebrows or eyelashes of children may indicate sexual exposure or abuse. (1)

Although a nuisance, pubic lice are not known to transmit any diseases. (2)

Like other lice, pubic lice come in three stages: the egg (or nit), the nymph, and the adult louse. Pubic lice nits are oval and yellow to white in color. They’re very small and can be difficult to see, especially since they firmly attach to the shaft of pubic hair.

Pubic lice nits hatch into nymphs after about 6 to 10 days of gestation. The nymph is simply an immature louse, and while it looks like an adult pubic louse, it’s smaller and will take another two to three weeks to mature into adulthood.

Once fully grown, pubic lice are either tan or grayish-white in color, have six legs, and feed off of human blood. (1) Pubic lice grow to be about 1/16 inch (1.6 millimeters) or less, which is about the size of a pinhead. They’re often dubbed “crabs” because their two front legs have pincher claws that resemble the crustacean. (3)

It’s possible to have pubic lice and experience no symptoms, especially if the initial infestation only involves a few lice and a few lice eggs. It may take up to four weeks until the lice nits hatch for symptoms to begin.

Some other indications that you could be dealing with a pubic lice infestation include:

• Visible Lice Eggs or Lice One way to home in on a diagnosis is to see lice nits or crawling lice in the genital area. The lice eggs may appear to simply be small, white dots in the pubic hair that are difficult to remove. (4)
• Itchiness Many people with pubic lice struggle with itchiness in the genital region. This sensation can get worse at night when lice become more active, burying their heads inside the pubic hair follicles to access blood. (5)
• Blood in Underpants Tiny specks of blood in the underwear can indicate that pubic lice are present. (4)
• Inflammation At times, an allergic reaction to the proteins in the pubic lice saliva can cause the pubic area to become inflamed and even develop hives and wheals. This can bring about even more intense itching, which can then domino into a secondary bacterial infection. (Scratching can also spur the spread of pubic lice.) (5)
• Discoloration Pale bluish spots may appear on the thighs, buttocks, or lower abdomen. (4)
• Eyebrow Irritation When young children are exposed to pubic lice, they may experience an irritation or infection of the eyelids called blepharitis. (5)

You may suspect a case of pubic lice if you have itching in the pubic area — or possibly by seeing lice eggs or adult lice with the help of a magnifying glass. But a physician can confirm an active pubic lice infestation through a physical examination of the pubic and genital area. (6)

Some physicians may also use an ultraviolet light or a microscope for help making an accurate diagnosis. (7) While at the doctor’s office, all individuals with pubic lice should also be evaluated for other sexually transmitted diseases. (2) If pubic lice is suspected in a child, the child’s eyelashes should be examined with a high-powered magnifying glass. (5)

Anyone can get pubic lice, and getting a diagnosis has nothing to do with your cleanliness or hygiene. (8) Infestations of pubic lice are found worldwide and occur in all races, ethnicities, and socioeconomic levels. (1)

It’s estimated that 3 million cases of pubic lice are diagnosed in the United States every year. The vast majority of these cases arise through sexual contact, when lice move from the pubic hair of one person to the pubic hair of another. It’s important to note that sexual intercourse is not the only way to transmit or become infested by pubic lice — transmission can happen through contact alone.

In addition, it’s rare but possible to acquire pubic lice from sharing clothing, bed linens, or towels with a person who has an active pubic lice infestation. (8) But it’s a myth that you can get pubic lice by sitting on a toilet seat. (Pubic lice require a warm human body to survive and have no feet to walk on a toilet seat.) (1) 

Dogs, cats, and other animals play no role in the transmission of pubic lice. (9)

There are a few different over-the-counter (OTC) pubic lice treatment options. These treatments are often the same as what you would choose to eradicate a case of head lice, and include products like Nix and Rid. But if these OTC options don’t work, a prescription may be in order. (6)

Regardless, sex partners should also be treated. (7) When using a topical treatment — OTC or otherwise — it will need to be applied to all areas of the body that may be involved, including near the rectum, thighs, lower abdomen, and underarms. (4) 

Finally, know that shaving won't get rid of pubic lice. (6)

Some treatments for pubic lice include:

• Over-the-Counter Lotions and Mousses These pubic lice–killing options contain either permethrin or a mix of pyrethrins and piperonyl butoxide. To use, wash and dry the pubic area, apply the medicine as directed, leave on for 10 minutes, then rinse out. (9)
• Prescription Shampoo Even though lindane shampoos, such as Kwell and Thionex, kill both lice and nits, this is not considered a first-line treatment because it can be toxic — especially for those with a seizure disorder and for pregnant or breastfeeding women. Lindane is generally reserved for people who’ve experienced failure with, or cannot tolerate, another treatment. (10)
• Petroleum Ointment If eyelashes or eyebrows are infested with pubic lice, use a cotton swab to apply prescription-grade petroleum jelly to them at night — and wash it off each morning — for 8 to 10 days. (OTC petrolatum jelly, like Vaseline, can irritate the eyes.) (10)

After the initial lice treatment, there are still important steps to take to take to keep pubic lice at bay — and to relieve the itch:

• Nit pick. After treatment, many nits will remain attached to the pubic hair shafts. These can be removed with fingernails or with a fine-toothed lice comb. (9)
• Apply hydrocortisone cream. Itching may persist even after a successful eradication of pubic lice. If so, a hydrocortisone cream will help quell the itch. (8)
• Wash clothing and bedding. Machine wash (at 130 degrees F or higher) any clothes, towels, and bed linens that the infested person used two to three days prior to treatment. Machine dry them at the hottest setting. (10)
• Dry-clean or seal other items. Clothing and bedding that cannot be machine washed should either be taken to the dry cleaner or tightly sealed in a plastic bag for two weeks. (10)
• Notify sex partners. Anyone who has had sexual contact (oral, anal, or vaginal) with the infested person within the previous month should be notified that they’re at risk for pubic lice. (5)
• Avoid sexual contact. Do not engage in oral, anal, or vaginal sexual contact until the infestation has been successfully treated. (10)
• Repeat treatment. If, within 9 to 10 days, live lice are still found, treat again. (10)