What Are Pubic Lice (Crabs) and How Do They Spread?

Pubic lice usually affect the genital area, but may also appear in other areas such as the abdomen or armpits. How do they spread? We'll tell you all about them in this article.
What Are Pubic Lice (Crabs) and How Do They Spread?

Written by Carmen Martín

Last update: 27 May, 2022

“Crabs” are the common slang name for pubic lice. They’re small insects that live in the pubic hair of humans. This condition is considered a sexually transmitted disease, although that isn’t the only way they can be transmitted.

Experts estimate that approximately one million people catch pubic lice every year. It’s very common. The insect that causes it is called Pthirus pubis. It feeds on blood and its bites produce a very intense and bothersome itching in the genital area.

Interestingly, throughout history, some texts have mentioned the existence of pubic lice, even the Bible itself. Although they’re similar to head lice, the main difference is that these lice tend not to transmit any other disease. However, it’s a very uncomfortable infection that can also affect the social life of those who suffer from it. Therefore, in this article, we’ll explain everything you need to know about pubic lice and how they spread.

How do public lice act?

A woman with a crabs infection.

In most cases, pubic lice are spread sexually. However, the infection can spread in other ways.

As we mentioned above, pubic lice are small insects that live exclusively in humans, specifically in the genital area. Pubic lice have some resemblance to the shape of marine crabs. They adhere to the hair thanks to a substance that acts as cement. Once there, they bite the skin. The bite is so intense that it causes itching due to certain components of their saliva and feces.

Typically, symptoms manifest about a week after the infection. In addition to itching, it’s common for lumps and bumps on the skin to appear, as well as scratching-related injuries.

Although they often only affect the pubic area, pubic lice can spread to other areas. For example, it’s important to know that it can affect a person’s chest hair, armpits, or abdomen.

An important fact is that they can even appear in the eyelashes. This is common in children who have been sexually abused. Therefore, the presence of this type of lice in children sometimes guides pediatricians to cases of rape and sexual abuse.

How pubic lice spread

Experts tend to consider pubic lice a sexually transmitted disease. This condition is most commonly due to sexual contact with a person who’s already infected. However, this isn’t the only way they can spread.

Although less frequent, pubic lice can also spread by the use of certain clothing, sheets, or towels of an infected person. However, it’s almost impossible to contract the infection in areas such as bathrooms or toilets.

This is because this insect can’t live away from the human body for long periods. They need a temperature of approximately 82°F or higher to be able to survive. Still, anyone who has this infection should make sure to properly clean all nearby objects and clothing.

You may like this article: Fight Lice Successfully with These 5 Home Remedies

How a pubic lice infection is diagnosed and treated

A woman at the doctor's office.

A physical examination is usually enough to diagnose pubic lice. Usually, they can be observed with the naked eye.

The diagnosis of pubic lice is very simple because it’s usually enough to observe the genital area. They’re usually visible to the naked eye. Also, the clinical picture is very characteristic. Thus, the doctor doesn’t usually need any other additional evidence.

Certain creams, shampoos, and lotions that kill the insects can treat the condition. Most people often require more than one use to kill all the lice. Also, it’s essential to properly clean all clothing, towels, and sheets.

However, the most important thing is to be aware of the need to warn nearby people, especially sexual partners, since this is a highly contagious infection.

This article may interest you: Seven Natural Ways to Get Rid of Lice and Nits


Pubic lice are tiny insects that cause itching in areas where there’s hair, especially on the genitals. They’re usually transmitted through sexual intercourse but can also spread by clothing or other fabrics such as sheets.

If you have any questions about the infection, you need to consult your doctor. They’ll indicate the most appropriate treatment and some recommendations to eliminate the disease.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.