What Are Crabs On Humans?

“Crabs” is the common slang name for pubic lice, tiny parasitic insects that live in coarse body hair and feed on human blood. The medical name is Pthirus pubis. They are not the same as head lice, and they are not a sign of poor hygiene. Anyone who has close physical contact with an infected person can get them. The name comes from their crab-like appearance under a microscope — they have wide bodies and large front claws.

These insects are small, about the size of a pinhead, but they cause real discomfort. The main symptom is itching in the genital area, which happens because the lice bite the skin to feed. The bites cause an allergic reaction in most people, and that reaction is what produces the itch. Pubic lice are treatable, and the treatment is straightforward when you follow the right steps.

What Do Crabs Look Like On The Skin?

Pubic lice are visible to the naked eye, though they are small. Adults are about 1.1 to 1.8 millimeters long — roughly the size of a sesame seed. They are grayish-white or tan in color. They may look darker after feeding because they have ingested blood.

The lice attach their eggs, called nits, to the base of hair shafts. The nits are tiny, oval-shaped, and usually pale yellow or white. They can look like dandruff, but unlike dandruff, they do not flake off easily when you brush or shake the hair. The nits are firmly cemented to the hair.

You may also see small red or blue spots on the skin. These are bite marks or areas where the lice have fed. In some cases, the bites cause a bluish-gray discoloration called maculae caeruleae. This is not a bruise from injury — it is a reaction to the louse saliva.

How Do People Get Pubic Lice?

Pubic lice spread through close physical contact, most commonly sexual contact. The lice crawl from one person’s hair to another’s during skin-to-skin contact. They cannot jump or fly. They move by crawling, which means transmission requires direct contact with infested hair.

Less commonly, lice can spread through shared items. Towels, bedding, clothing, or toilet seats can carry lice for a short time if an infested person used them right before. But this is not the main way they spread. The lice need a human host to survive — they cannot live away from the body for more than about 24 to 48 hours.

Pubic lice are not spread by shaking hands, hugging, or casual contact. You cannot get them from a swimming pool. The idea that you can catch crabs from a public toilet seat is mostly a myth; the conditions would have to be exactly right, and it is extremely unlikely.

What Are The Symptoms Of Crabs On Humans?

The most common symptom is itching in the genital area. The itching usually becomes noticeable about five days to several weeks after exposure. That delay happens because the itching is an allergic reaction to the louse bites, and it takes time for the body to develop that sensitivity.

Other symptoms include:

• Visible lice or nits in pubic hair
• Red or irritated skin from scratching
• Small blue-gray spots on the skin
• A feeling that something is moving in the hair
• Irritation in the armpits, chest hair, or eyelashes in severe cases

Pubic lice can also live in other coarse body hair. This includes armpit hair, chest hair, leg hair, beards, and eyelashes. Eyelash infestation is uncommon and usually happens in children, which can be a sign of a different type of exposure that needs medical attention.

How Are Pubic Lice Diagnosed?

A doctor can usually diagnose pubic lice with a simple visual exam. They look for live lice moving in the hair or for nits attached to the hair shafts. In some cases, they may use a magnifying glass or a special light called a Wood’s lamp, which can make the nits easier to see.

You can also check yourself at home. Use a bright light and a magnifying glass if you have one. Part the hair in small sections and look for movement or for small oval eggs attached near the base of the hairs. The lice move quickly, so you may need to look carefully.

If you find lice or nits, you do not need to see a doctor for diagnosis — you can start treatment. But you should see a doctor if you are pregnant, if the infestation is in your eyelashes, or if over-the-counter treatment does not work after two full courses.

What Is The Treatment For Crabs?

Treatment for pubic lice involves using a medicated lotion or cream that kills the lice. The most common over-the-counter options contain permethrin or pyrethrin. These are the same active ingredients used in many head lice treatments, but the products are applied to the pubic area instead of the scalp.

Follow the product instructions exactly. Most treatments require you to apply the product to clean, dry hair and leave it on for a specific amount of time — usually about 10 minutes — before washing it off. Do not leave the product on longer than directed. Do not use more than directed. These are pesticides, and overuse can irritate the skin.

After treatment, you need to remove the nits. The medication kills the live lice, but the eggs may survive. Use a fine-toothed comb to remove nits from the hair. This step is essential — if you leave the nits in place, they can hatch and start the infestation again.

A single treatment is often not enough. Most guidelines recommend a second treatment after 7 to 10 days to kill any lice that hatched from eggs that survived the first round. Check yourself carefully after treatment and repeat if you still see live lice.

What About Prescription Treatments?

If over-the-counter treatments do not work, a doctor can prescribe stronger options. Prescription treatments include malathion lotion or ivermectin pills. These are used when resistance to permethrin is suspected or when the infestation is severe.

Ivermectin is taken as a pill, usually two doses about a week apart. It is effective but requires a prescription. Malathion is a lotion applied to the affected area, but it is flammable, so you must let it dry completely before using a hair dryer or getting near an open flame.

Do not use these prescription treatments without a doctor’s guidance. They are stronger than over-the-counter options and carry different risks. A doctor will decide which treatment fits your situation based on your health history and the severity of the infestation.

How Do You Get Rid Of Crabs In Your Home?

You do not need to fumigate your house. Pubic lice cannot survive long away from a human host, so the risk of reinfestation from your environment is low. But you should take some basic steps to be safe.

Wash all bedding, towels, and clothing that came into contact with the infested person in the past few days. Use hot water — at least 130°F (54°C) — and dry on high heat. Items that cannot be washed, like heavy blankets or pillows, can be dry-cleaned or sealed in a plastic bag for 72 hours. By that time, any lice or nits will have died.

Do not share towels, bedding, or clothing until the infestation is fully treated. Vacuuming furniture and carpets is reasonable but not strictly necessary. The main risk of reinfestation is close contact with an untreated person, not your furniture.

Should Your Partner Be Treated Too?

Yes. If you have pubic lice, anyone you have had close physical or sexual contact with in the past month should be checked and treated if needed. Treating only one person in a couple leads to reinfestation — the lice simply crawl back and forth.

This includes current sexual partners, even if they have no symptoms. Not everyone develops itching right away, and some people carry lice without noticing. Treating both partners at the same time breaks the cycle.

You do not necessarily need to treat past partners from months ago, but you should inform anyone you were intimate with recently so they can check themselves. It is not a comfortable conversation, but it is the responsible one. Pubic lice are not a sign of infidelity — anyone can get them from any close contact.

How Do You Prevent Crabs?

The only reliable way to prevent pubic lice is to avoid close physical contact with someone who has them. Condoms do not prevent pubic lice because the lice live in the pubic hair, not on the penis or in the vagina. Condoms reduce the risk of sexually transmitted infections, but they do nothing for lice.

Do not share towels, underwear, or bedding with someone you do not know well. This is a low-risk but real route of transmission. If you stay in a hotel or hostel, the sheets should be clean — commercial laundry processes kill lice.

If you have been exposed to someone with pubic lice, check yourself carefully for a few weeks. The lice may not be visible immediately, and the itching may take time to appear. Early detection makes treatment easier and reduces the chance of spreading it to others.