Pubic lice (crabs)

What are pubic lice?

Pubic lice are tiny parasitic insects that live on coarse human body hair, such as pubic hair. They are around 2mm long and aren’t that easy to see. They are sometimes also known as ‘crabs’ because they have two large front legs that look similar to the claws of a crab.

As well as being found in pubic hair, they are also sometimes found in hair on:

• Armpits and legs
• The chest, belly and back
• And the face – on beards, moustaches, eyelashes and eyebrows

But, unlike head lice, they don’t live on scalp hair.

What are the symptoms?

It can take several weeks before any symptoms to appear, but these can include:

• Itching in the affected areas
• Inflammation and irritation caused by scratching
• Black powder in your underwear
• Blue spots or small spots of blood on your skin caused by lice bites

Itching is the most common symptom and is an allergic reaction to the lice’s saliva. It usually becomes worse at night because this is when the lice are most active.

How do you catch them?

People don’t get pubic lice because of poor personal hygiene. They normally spread through close bodily contact with an infected person because the lice can’t fly or jump so crawl from hair to hair. They also need human blood to survive, so will only leave the body to move from one person to another.

Sexual contact is the most common way to spread pubic lice. This includes vaginal, anal and oral sex. Other types of close bodily contact, such as hugging and kissing can spread the lice. It’s also possible – though much rarer – for pubic lice to be spread through sharing clothes, towels and bedding too.

How do you prevent them?

Unfortunately using condoms and other methods of barrier contraception won’t protect you against pubic lice. The only way to reduce your risk is by avoiding sexual or close bodily contact with an infected person.

If you get them, you can stop the lice from spreading to others by:

• Washing bedding, towels and clothes above 50°C to kill the lice and their eggs
• Making sure anyone who you have had close contact with is treated

How do you get tested?

If you think you have pubic lice, visit your GP, sexual health service or GUM clinic. Pubic lice are usually easy to diagnose by examining the affected area. The doctor or nurse may use a magnifying glass to look for signs of the lice, such as pale-coloured eggs or the lice themselves.

What treatment is available?

The lice are treated at home by applying a special insecticide cream, lotion or shampoo to the affected area. Sometimes the whole body must be treated, taking care to avoid the eyes.

The treatment usually needs to be repeated after three to seven days. To prevent re-infection, sexual partners should be examined and treated even if they do not have any symptoms.

If you do have pubic lice, you will be advised to have a full sexually transmitted infection screen. You can get a free, confidential STI screen at a sexual health clinic like those run by Virgin Care, a genitourinary medicine (GUM) clinic, most contraception clinics and some GP surgeries.

Useful links

• NHS Choices has lots of information about STIs including a specific page on pubic lice
• Brook has more information and advice on STIs written for people under 25, including pubic lice