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Pubic lice

Introduction

Pubic lice (Phthirus pubis) are tiny parasitic insects that live in coarse human body hair, such as pubic hair.

They spread through close body contact, most commonly sexual contact. 

After you get pubic lice, it can take five days to several weeks before symptoms appear. The symptoms include:

  • itching in the affected areas
  • inflammation or irritation in the affected areas caused by scratching
  • black powder in your underwear
  • blue-coloured spots on your skin where the lice are living, such as on your thighs or lower abdomen (these are caused by lice bites)
  • tiny blood spots on your underwear or skin

Read more about the symptoms of pubic lice.

As well as being found in pubic hair, the lice are also sometimes found in:

  • underarm and leg hair
  • hair on the chest, abdomen and back
  • facial hair, such as beards and moustaches
  • eyelashes and eyebrows (very occasionally)

Pubic lice are sometimes called crab lice because they look similar to crabs. Adult lice are about 2mm long and are yellow-grey or dusky red in colour. The lice attach their eggs to the base of hairs. The white cases left after the eggs have hatched are called nits.

The lice do not transmit HIV or other sexually transmitted infections (STIs), but a sexual health check-up is always recommended if you have pubic lice.

Pubic lice are not the same as head lice and do not live in the hair on your scalp.

How do you get pubic lice?

Pubic lice are not linked to poor personal hygiene. They are spread through close body contact with someone who has them.

The lice crawl from hair to hair but cannot fly or jump. They need human blood to survive, so generally only leave the body to move from one person to another.

Pubic lice are most commonly passed on during sexual contact. Condoms will not prevent them from being passed to another person.

It is also possible for pubic lice to be spread through sharing clothes, towels and bedding.

When to seek medical advice

If you think you may have pubic lice, go to your GP or your nearest sexual health clinic, also known as a genitourinary medicine (GUM) clinic, for a check-up as soon as possible.

Is is usually easy to diagnose pubic lice by examining the affected area. The doctor or nurse may use a magnifying glass to look for signs of the lice, such as the pale-coloured eggs or the lice themselves.

If you have pubic lice as a result of sexual contact, you should be tested for other sexually transmitted infections (STIs).

Treating pubic lice

You can treat pubic lice yourself at home by using a special type of lotion, cream or shampoo. Your doctor or pharmacist can advise you on which treatment to use and how to use it. It's important to follow this advice.

The treatment is applied to all the hairy areas on your body, except for the hair on your head, eyebrows and eyelashes. It usually needs to be repeated after three to seven days.

If the treatment doesn't work, you may need to use another type. This is because pubic lice can sometimes develop resistance to certain treatments. Your doctor or pharmacist can advise you on suitable alternatives.

It's also important to treat anyone you have had close body contact with, including current sexual partners and household members.

Read more about treating pubic lice.

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Symptoms

After you come into contact with public lice, it can take five days to several weeks before you notice any symptoms.

The symptoms of pubic lice are the same for both men and women, and include:

  • itching in the affected areas
  • inflammation and irritation in the affected areas caused by scratching
  • black powder in your underwear
  • blue-coloured spots on your skin where the lice are living, such as on your thighs or lower abdomen (these are caused by lice bites)
  • small spots of blood on your skin that are also caused by lice bites

Itching

Itching is the most common symptom of pubic lice. However, it can take several weeks after the first infestation for you to notice any itching.

The itching is not caused by the lice biting you. It is due to an allergy (hypersensitivity) to the louse saliva.

The itching is usually worse during the night when the lice are more active.

Pubic lice and eggs

Adult pubic lice are very small (about 2mm long) and are difficult to see. The lice are yellow-grey or dusky red in colour and have six legs.

Two of the legs are larger than the others and look like the claws of a crab. The lice use these to grasp onto hairs.

The lice lay their eggs in sacs that are firmly stuck to hairs and are a pale brownish colour. When the eggs hatch, the empty sacs are white.

Although pubic lice and lice eggs are very small and not easy to see, they may be visible in coarse hair anywhere on your body (apart from the hair on your head).

You may also find empty white eggshells (nits) on your hairs, although this does not necessarily mean that you still have an infestation of pubic lice.

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Causes

Pubic lice are not related to poor personal hygiene. They are usually caught through close bodily contact with someone who is infected.

The lice crawl from the hair of one person to the hair of another person. They cannot jump, fly or swim.

Sexual contact

Pubic lice are most commonly passed on through sexual contact. This includes vaginal, anal and oral sex.

Using condoms and other methods of barrier contraception does not protect you against pubic lice.

Other types of close bodily contact, such as hugging and kissing, can also spread the lice.

Other ways of spreading public lice 

It is also thought that you can get pubic lice from infected items such as:

  • clothing
  • bed linen
  • towels
  • toilet seats

However, it's much rarer for lice to be spread in this way.  

The life cycle of pubic lice

Pubic lice live for one to three months. During this time, the female louse can lay up to 300 eggs. The eggs hatch after 6 to 10 days, and two to three weeks later the lice reach maturity and can start reproducing.

When not on a human body, pubic lice can live for up to 24 hours. However, the lice depend on human blood to survive so they rarely leave the body other than to move to another person. Pubic lice do not live on other animals.

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Diagnosis

If you think you may have pubic lice, get checked by a healthcare professional as soon as possible. You can go to your GP or visit a sexual health clinic. Sexual health clinics are sometimes called genito-urinary medicine (GUM) clinics.

Your GP or the healthcare professional treating you will look for evidence of pubic lice, including:

  • itchy red spots,
  • dark brown or black powder or specks (louse droppings),
  • blue spots on the skin, or
  • nits (empty egg shells).

Your diagnosis can only be confirmed by finding a live louse or eggs capable of hatching.

Some people will not develop visible signs or symptoms straight away, and you may be asked to come back for another appointment later.

Infestations through sexual contact

As part of the diagnosis, your GP or healthcare professional will ask you whether the infestation has been transferred through close body contact or sexual contact. If the pubic lice were transferred through sexual contact, your GP will recommend that you are screened for other sexually transmitted infections (STIs) as a precaution.

Do I have to pay for tests at sexual health clinics?

Sexual health services are free and available to everyone, regardless of age. 

If you go to your GP, you will probably have to pay a prescription charge for the treatment.

What happens at a sexual health (GUM) clinic?

  • Some clinics are drop-in clinics, while others require you to book an appointment. Phone the clinic to find out.
  • When you attend a clinic, you will be asked to fill in a form with your name and contact details. You do not have to give your real name or tell staff who your GP is if you do not want to. Any details you give will be confidential. 
  • You will be asked why you have attended the clinic. Do not be embarrassed. Say that you think you may have a sexually transmitted infection (STI). 
  • You will be asked about your sexual history, for example when you last had sex, whether you used condoms and whether you have had an STI before.
  • If you are attending the clinic for pubic lice, you may be offered tests for other STIs. You do not have to agree, though it is recommended. Tests can only be done with your consent.
  • You may need to give a urine or blood sample for other STI tests.
  • Results from tests for STIs are usually available straight away.
  • If you need any treatment, this will be discussed with you.
  • If you have an STI, your partner (and previous partners) will need to be tested and, if necessary, treated to prevent the infection being passed on to anyone else. 
  • Staff at the sexual health clinic will be able to advise you about the sexual partners who will need to be contacted, and may be able to contact them on your behalf. If you wish, your anonymity will be protected when contacting your previous sexual partners.

 

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Treatment

Pubic lice can be treated at home with insecticide cream, lotion or shampoo. It will usually need to be applied once and repeated after three to seven days.

Most treatments need to be applied to the affected area and the whole body, apart from your scalp, face, eyebrows and eyelashes (but including your beard or moustache if you have one). Your doctor, nurse or pharmacist can give you more advice about this.

Everyone you have had close bodily contact with should also be treated at the same time. This includes any sexual partners you have had in the past three months and all members of your household.  

Sometimes, pubic lice can be difficult to get rid of because they can develop resistance to insecticide treatments. If this is the case, you may need to try more than one type of treatment. Your doctor or pharmacist can advise you on suitable alternatives.

Treating yourself

You can treat yourself at home with an insecticide cream, lotion or shampoo. They are available on prescription from your doctor or you can buy them over the counter from your pharmacy.

Before using the treatment, speak to your doctor or pharmacist about the correct way to use it. Follow their instructions, even if they are different to those on the packaging. 

Always ask for advice if the treatment is for:

  • a child under 18 years of age
  • someone who is pregnant or breastfeeding

These people may require a specific type of treatment. 

Lotions and cream

The two most commonly used insecticides are:

  • malathion 0.5% aqueous lotion
  • permethrin 5% dermal cream

In most cases, the instructions for using malathion lotion or permethrin cream will be as follows:

  • Apply the lotion to your whole body, particularly any hairy areas, when you are clean, dry and cool. Do not apply the lotion to your face, the hair on your head, your eyebrows or eyelashes.
  • Apply the lotion to your beard and moustache, if you have one.
  • Apply the lotion to your pubic area, including any pubic hair, hair between your legs and hair around your anus.
  • Be careful not to get the lotion in your eyes. If you do, rinse your eyes thoroughly with water.
  • As an approximate guide, an adult will need around 100ml of lotion or 30–60g of cream for one application.
  • Leave malathion lotion on for 12 hours or overnight. Leave permethrin cream on for 24 hours.
  • Reapply the treatment if you wash any part of your body during the treatment time.
  • After the correct treatment time has passed, wash the lotion or cream off. 
  • Repeat the treatment after three to seven days as instructed.

Do not use medication more than twice.

Treating an eyelash infestation

If your eyelashes are infested, seek specialist advice and help from your doctor.

You cannot use the same insecticide lotion or cream as you use on your body because it will irritate your eyes. Your doctor will be able to recommend an alternative treatment for you.

Eye ointment

An eye ointment with a white or yellow soft paraffin base may be recommended. This works by coating the lice in the greasy ointment and suffocating them. You should:

  • Apply the ointment to your eyelashes twice a day, ensuring that all your eyelashes are well covered.
  • Each time you reapply the ointment, first gently wipe your eyelashes and eyelids clean with a tissue. Throw the tissue away afterwards. 
  • Continue the treatment for at least eight days.
  • If you can still see lice or unhatched eggs (not empty eggshells, which are called nits), continue the treatment for 10 days because the eggs can take this long to hatch.

Side effects

Insecticides that are used to treat pubic lice may cause skin or eye irritation, such as itchiness, redness, stinging or burning.

If you have these side effects, wash the insecticide off the irritated area. If the insecticide gets into your eyes, rinse them thoroughly using plenty of water.

Some aqueous and alcoholic-based medications may discolour permed, coloured or bleached hair. Check the patient information leaflet for more details.

Follow-up treatment

The first treatment application will probably kill the lice, but the eggs may not have been destroyed. This means that more lice could hatch and the cycle will start again. Reapplying the treatment after seven days ensures that any lice are killed before they are old enough to lay more eggs.

Check for lice a week after your second treatment, or return to your doctor, sexual health clinic, or genitourinary medicine (GUM) clinic so that they can check for you.

If you find empty eggshells (nits), it does not necessarily mean that you are still infested. They can remain stuck to the hairs even after treatment. However, if you find lice or eggs that could still hatch, your treatment has not been successful and you should speak to your doctor.  

The lice may be resistant to the treatment you have used and your doctor may recommend a different treatment.

Treating other people

To prevent re-infestation, anyone that you are in close contact with should also be treated at the same time as you. This includes your sexual partners and all members of your household, even if they do not have symptoms.

Infestations from sexual contact

If your pubic lice were caught through sexual contact, your GP may refer you to a GUM clinic so that you can be screened for other sexually transmitted infections (STIs), such as chlamydia. 

Staff at the clinic will recommend that you inform any sexual partners you have had in the past three months so that they can also be examined for pubic lice and treated if necessary.

Some people feel angry, upset or embarrassed about talking to their current or former sexual partners about pubic lice. Do not be afraid to discuss your concerns with clinic staff. They can help you decide the best way to make contact. They can also contact a partner without releasing your details, if you prefer.

When can I have sex again?

Avoid having sex (vaginal, anal or oral) or close bodily contact until both you and your partner have finished the course of treatment, including any follow-up treatment.

This is to avoid re-infection or passing the infection on to someone else.

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Complications

A pubic lice infestation can sometimes lead to minor complications, including skin and eye problems.

Skin problems

If you have pubic lice, your skin may become irritated from scratching.

Scratching can cause scratch marks on your skin, or it could lead to an infection such as impetigo (a contagious bacterial skin infection) or furunculosis (boils on the skin). 

Eye problems

Eye infections, such as conjunctivitis, and eye inflammation, such as blepharitis, can sometimes develop if your eyelashes have been infested with pubic lice.

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