Pubic lice, commonly called “crabs,” spread primarily through sexual contact. Any intimate, skin-to-skin contact where pubic areas touch gives the lice a chance to crawl from one person to another. They don’t jump or fly. They can only move by gripping hair with their claw-like legs, which is why close physical contact is almost always required.
Sexual Contact Is the Main Route
The vast majority of pubic lice cases come from sexual or intimate person-to-person contact. During sex, the lice crawl directly from one person’s body hair to another’s. Any form of sexual activity that involves close genital contact can transmit them, including vaginal, anal, or even prolonged body-to-body contact where coarse body hair is touching. Condoms do not prevent transmission because the lice live on the skin and hair surrounding the genitals, not in bodily fluids.
Pubic lice are distinct from the head lice that affect schoolchildren. They’re a different species, smaller and wider with a crab-like shape (hence the nickname). They strongly prefer coarse body hair, so they’re most often found in the pubic region, but they can also settle on chest hair, armpit hair, leg hair, beards, mustaches, and even eyelashes or eyebrows in some cases.
Can You Get Crabs From Towels or Toilet Seats?
It’s possible but uncommon. The CDC notes that pubic lice can occasionally spread through shared clothing or bedding, and very rarely from a toilet seat that was just used by someone with an active infestation. The reason non-sexual transmission is so unusual is biological: pubic lice die within one to two days when separated from a human host. They need warmth and blood meals to survive, so they can’t live long on fabric or hard surfaces. A louse clinging to a towel or bedsheet would need to find a new host quickly, making the odds low compared to direct body contact.
That said, it’s still worth avoiding shared towels, underwear, or bedding with someone who has an active infestation. The risk is small, but it’s not zero.
What Happens After Exposure
Once a louse reaches a new host, it grips onto a hair shaft and begins feeding on blood. Female lice lay eggs (called nits) that attach firmly to hair near the skin’s surface. These eggs hatch after about a week, producing nymphs that go through three molts before becoming mature adults capable of reproducing themselves.
Many infestations are actually asymptomatic, at least initially. When symptoms do appear, the most common one is itching in the pubic area, caused by an allergic reaction to louse saliva. Some people also develop small bluish-gray spots on the skin where lice have been feeding. You may be able to see the lice themselves, which are tiny (about 1 to 2 millimeters) and tan or grayish-white, or their nits, which look like small oval dots attached to the base of hairs.
Treatment Options
Over-the-counter treatments are the standard first step. A 1% permethrin cream rinse or a pyrethrin-based product is applied to the affected area and washed off after 10 minutes. These are the same active ingredients found in many lice shampoos sold at pharmacies. You’ll typically need to repeat the treatment after 7 to 10 days to kill any newly hatched nymphs that survived the first round.
If over-the-counter products don’t work, prescription options exist. Topical ivermectin lotion is FDA-approved for pubic lice, and a prescription malathion lotion can also be effective, though it’s used off-label for this purpose. A healthcare provider can help determine the right approach if a standard treatment fails.
Cleaning Your Home After an Infestation
Because lice can survive briefly on fabric, you’ll want to wash all bedding, towels, and recently worn clothing in hot water, at least 130°F, and dry everything on a high-heat dryer cycle. Items that can’t be washed should be sealed in a plastic bag for about two weeks, long enough for any lice or eggs to die without a host. Fumigant sprays for furniture aren’t necessary and aren’t recommended.
Sexual partners from the previous month should be notified so they can check for symptoms and treat if needed. Avoid sexual contact until both you and your partner have completed treatment and confirmed the infestation is cleared.
Why Crabs Have Become Less Common
Dermatologists and sexual health clinics in several countries have reported a noticeable decline in pubic lice cases over the past two decades. The leading explanation is the rise of pubic hair grooming. Since pubic lice need coarse body hair to cling to and lay eggs on, widespread waxing, trimming, and shaving has reduced available habitat. The lice haven’t disappeared entirely, but the trend has made infestations significantly less frequent than they were in the 1990s and earlier.