Smegma in men: what it is, why it builds up and how to clean it

Smegma is a natural white or yellowish substance that can build up under the foreskin, says Alder Hey Children's NHS Foundation Trust in its page for teenagers and young adults. The penis makes it to help keep itself lubricated and prevent dryness, the page says, and washing under the foreskin regularly will help stop any build-up. Other conditions can cause a white discharge or white patches too, so this guide also covers when to get checked.

What is smegma?

Smegma is a build-up of leaked urine, semen and dead skin cells shed from the foreskin and the head of the penis as part of normal skin wear and tear, says the British Association of Dermatologists (BAD).

For a one-line meaning or definition, the US National Library of Medicine's medical vocabulary describes smegma as a build-up of skin oil (sebum) and shed skin cells, especially the cheesy substance found under the foreskin.

The foreskin is the fold of skin covering the head of the penis (the glans), and the rim of the head is the corona, the BAD explains.

Is smegma normal, or bad for you?

Smegma is normal: Alder Hey's page for teenagers and young adults calls it a natural substance, and a Cambridge NHS hospital leaflet on smegma cysts in children says it is made up of normal secretions from the skin. If it builds up, Alder Hey's page for teenagers says, it can start to smell, become infected, or become red, swollen and painful, and you may need to see your doctor for treatment.

Is smegma dangerous? The BAD counts it as an irritant. An NHS West Yorkshire page for young people says a build-up can become a breeding ground for bacteria, which can cause balanitis (redness and swelling of the head of the penis). The NHS lists not washing your penis properly as a cause of balanitis.

What does smegma look like?

Alder Hey's page for teenagers describes smegma as white or yellowish, the US National Library of Medicine as cheesy, and the NHS West Yorkshire page as creamy.

Other causes of white stuff under the foreskin

Thrush can cause a white discharge, like cottage cheese, the NHS says; see our guide to thrush in men.

Balanitis (a swollen, sore head of the penis) can cause a thick discharge from under the foreskin, the NHS says.

Some sexually transmitted infections (STIs) can cause a discharge from the penis; with chlamydia, the NHS says, it can be white, cloudy or watery.

Lichen sclerosus can cause sore or sometimes itchy white patches on the penis, says Northern Ireland's nidirect, and the NHS says the foreskin may tighten and that the condition is not caused by poor personal hygiene.

Pearly penile papules, small shiny or skin-coloured bumps around the rim of the head, are normal, the BAD says; our guide to spots and bumps on the penis covers them and Fordyce spots.

The NHS says: "Do not try to diagnose the cause of penis lumps or spots yourself. Always get medical help." A GP or sexual health clinic can check.

What causes smegma to build up?

If the penis isn't kept clean, smegma builds up on the head of the penis and under the foreskin, says NHS West Yorkshire's page for young people. Urine plays a part too: small amounts can leak and get trapped under the foreskin, which the BAD says can lead to inflammation. The BAD calls urine the most common irritant of the skin of the penis.

A very tight foreskin that can't be pulled back can make it difficult to clean, Alder Hey's page for teenagers says; our guide to a tight foreskin (phimosis) has more.

Why do I have smegma if I wash regularly?

Washing doesn't stop your body making smegma: the penis produces it (Alder Hey's page for teenagers). A small 1986 US study of 47 uncircumcised boys and men (median age 6, so mostly children) found that how often they said they washed was not associated with smegma or inflammation; all of them reported washing at least two or three times a week. Those who pulled the foreskin back when washing were less likely to have smegma build-up or inflammation, though reported good hygiene didn't remove these problems entirely.

How do you get rid of smegma?

You can't stop your body making smegma, but you can wash it away. These steps to clean smegma from under the foreskin come from the NHS, NICE, Scotland's NHS inform and the BAD:

1. Gently pull the foreskin back, only as far as it goes (the NHS's advice for a tight foreskin, for adults only).
2. Wash with warm water, as the NHS's tight foreskin page says.
3. Gently remove any smegma when washing, as the BAD advises.
4. Dry gently. NICE's guidance on balanitis says to keep the foreskin pulled back until the head of the penis is dry, where possible; NHS inform says to dry gently with a towel before putting the foreskin back.
5. Always put the foreskin back over the head of the penis (the NHS's tight foreskin page). NHS West Yorkshire's page for young people says one that isn't put back might get stuck: this is paraphimosis, which the NHS calls a medical emergency (call 999 or go to A&E).

Soap or just water?

UK sources differ on soap. The NHS balanitis page says not to use soap or shower gel, while its tight foreskin page says warm water, or warm water and non-perfumed soap. NICE's guidance on balanitis says to avoid irritants such as soap, bubble bath or baby wipes. The BAD says soaps and bubble baths contain strong irritants, and NHS inform says not to use soap on or near the genitals, as it can be drying.

Washing under the foreskin: what UK health sources say

	Written for.	How often.	What it says about washing.
NHS: Balanitis	Men with balanitis	Every day	Gently pull back the foreskin and wash with warm water; no soap or shower gel; dry gently
NHS: Tight foreskin (phimosis)	Men with a tight foreskin	Regularly	Warm water, or warm water and non-perfumed soap; pull the foreskin back as far as you can (adults only) and always put it back; no perfumed soap, talc or deodorants
NICE CKS: Balanitis in adults (guidance for GPs)	Men with balanitis	Daily	Lukewarm water; avoid irritants such as soap, bubble bath or baby wipes; where possible, keep the foreskin pulled back until the head of the penis is dry
British Association of Dermatologists: Penile skincare	Everyone with a penis	Not given; warns that washing too much can strip natural oils and lead to dryness and irritation	Soaps and bubble baths contain strong irritants; nothing fragranced; gently remove any smegma; pat dry; no deodorant or cologne
NHS inform (Scotland): Managing genital symptoms	People with genital symptoms	Not given	Pull the foreskin back gently but fully, dry gently with a towel, then put it back; no soap on or near the genitals (it can be drying); no wet wipes
Brook (a charity for young people)	Young people	Every day	Warm water and soap; wash under the foreskin to prevent the build-up of smegma

The NHS and NICE say warm or lukewarm water. The NHS tight-foreskin page and BAD both rule out perfume and fragrance. They differ on soap. If your foreskin is tight, pull it back only as far as it goes, and never pull back a baby's or young boy's foreskin that is still attached (NHS). Sources: NHS, NICE CKS, BAD, NHS inform and Brook.

How often should you wash under your foreskin?

For men with balanitis, the NHS and NICE say every day; the NHS tight foreskin page says regularly. For men without symptoms, two pages for young people give a frequency: NHS West Yorkshire says once a day and Brook says every day. The BAD says washing too much can strip natural oils and lead to dryness and irritation.

Small habits that help

To reduce urine leakage, the BAD suggests gently pulling the foreskin back when you pee, then shaking the penis, or gently squeezing from the base of the shaft towards the head two or three times to push out the last drops of urine; the opening at the tip can then be dabbed dry with plain tissue. It also advises keeping pubic hair trimmed, as the hair can get trapped between the foreskin and the penis and cause tiny scratches and irritation; our guide to pubic hair removal for men covers trimming.

Why does my penis smell?

A build-up of smegma can cause an unpleasant smell, the BAD says. Brook, a charity for young people, says genitals in general should have a minimal smell, so a bad smell might be down to hygiene. Northern Ireland's nidirect lists a sore, itchy and smelly penis among the signs that should be checked by a GP or sexual health clinic.

A discharge that smells bad is different: NHS West Yorkshire, writing for young people, says it could be a sign of an infection or an STI, and to visit a GP or sexual health clinic. The NHS lists an unpleasant smell among the possible symptoms of balanitis and of thrush.

What does smegma smell like?

The BAD says only that a build-up can cause an unpleasant smell, and the US National Library of Medicine's definition calls smegma foul-smelling.

Does smegma cause cancer?

Smegma itself isn't thought to cause cancer: the European Association of Urology says it is not a carcinogen. Cancer Research UK calls penile cancer rare. Men with a tight foreskin have a higher risk; Cancer Research UK says the reason isn't clear and may be long-term inflammation or infection.

The NHS says penile cancer is most common in men over 50, and that roughly half of all penile cancers are caused by certain types of a virus called HPV. Other risks on its list include smoking, problems pulling back your foreskin to keep your penis clean (phimosis), PUVA light treatment for psoriasis and a weakened immune system. It says you may be able to lower your chances by getting the HPV vaccine if you can, using condoms, stopping smoking, and having a circumcision if you have phimosis and this is recommended to treat it.

Smegma in boys

This part is for parents: in boys, smegma can build up between the foreskin and the head of the penis as the two separate, says the Cambridge leaflet on smegma cysts in children. Most boys' foreskins do not pull back before the age of 5, and sometimes not until 10 or older, the NHS says; the foreskin usually separates from the head by itself, sometimes not fully until puberty. The BAD says that by 18 it should pull back easily.

Do not pull back a baby's or young boy's foreskin that is still attached to the end of the penis: the NHS says it could be painful and damage it. For babies, the NHS says to clean around the penis with cotton wool and warm water, with no need to pull back the foreskin. Lancashire Teaching Hospitals' leaflet says gently pulling it back during washing is fine only if it moves easily; if it doesn't pull back, leave it alone, and always put it back. If your child's foreskin has been pulled back and will not go back over the end of the penis, call 999 or go to A&E: the NHS calls this (paraphimosis) a medical emergency. NHS West Yorkshire's balanitis page for parents says to teach your child to wash his penis gently with warm water every day, without soap, bubble bath or baby wipes.

Alder Hey's page for parents says to see your child's GP or practice nurse about redness, irritation, swelling or pain in the penis or foreskin, and the GP if a foreskin still attached to the head of the penis is being pulled tight and causing pain or discomfort. For teenagers with a tight foreskin, NHS West Yorkshire's page for young people says to speak to a GP if it is painful or getting red and irritated. The NHS also says to see a GP if your child's foreskin is tight and swollen or painful, there's bleeding around it when peeing, a thick discharge from under it or an unpleasant smell, or your child has pain when peeing or difficulty peeing.

What are smegma pearls?

Smegma pearls are what the Cambridge leaflet calls smegma cysts or preputial pearls: small white or yellow lumps of skin cells and natural secretions trapped under the foreskin, common in uncircumcised boys. As they break down, they can look like whitish cottage cheese, sometimes seen in nappies or pants. They are usually painless, need no treatment and clear up on their own as the foreskin separates; they are not contagious and cause no long-term problems. The leaflet recommends warm baths and gentle daily washing, and says not to squeeze or pop one. Get medical advice, it says, if one becomes painful, infected or swollen, or if the foreskin becomes hard to pull back when it used to move easily.

When to see a GP or sexual health clinic

The BAD suggests checking your whole penis regularly, pulling back the foreskin if you have one, for rashes or changes in colour, new or changing lumps or bumps, warts, boils or sores, and seeing a healthcare professional if you have any concerns.

See a GP or go to a sexual health clinic if:

• you have a lump, sore or ulcer on your penis, or a rash or spots on your penis
• the tip of your penis is swollen, itchy, sore and red (redness may be less obvious on brown or black skin)
• you notice any changes to how your penis looks, or you have symptoms that are not going away
• you have symptoms of balanitis, such as the head of your penis being swollen, itchy, sore or red, or you have balanitis and treatment has not worked
• you have a discharge that smells bad (Brook and NHS West Yorkshire, for young people), or a sore, itchy and smelly penis (nidirect)
• you have a discharge from your penis, you or a sexual partner think you might have chlamydia or gonorrhoea or have symptoms of trichomoniasis, or you or a partner have had sex without a condom

See a GP if:

• your foreskin is tight and swollen or painful; there's bleeding around your foreskin when peeing, a thick discharge from under the foreskin, or an unpleasant smell; you have pain when peeing or difficulty peeing; or you're having painful erections (the NHS's tight foreskin page)
• you are unable to pull your foreskin back fully, especially if it becomes red or painful (the British Association of Urological Surgeons), or it cannot be pulled back by the age of 18 (BAD)
• you have a growth, lump or sore that does not heal within 4 weeks, discharge or bleeding from your penis, or any of the other symptoms of penile cancer (the NHS lists a rash and a change in the colour of the skin of your penis or foreskin among its most common symptoms, and says other symptoms may include a lump in your groin, feeling tired, tummy pain and losing weight without trying)
• you have an itchy white patch on your genitals, or you've been diagnosed with lichen sclerosus and either treatment is not helping or you have pain when going to the toilet or having sex
• you have symptoms of thrush for the first time, thrush keeps coming back (more than 4 times in 12 months), treatment for thrush has not worked, or you have thrush and are under 16 or over 60, or have thrush and a weakened immune system (for example, because of diabetes, HIV or chemotherapy); the NHS says a sexual health clinic may also be able to help if you think you have thrush

The NHS says some symptoms of penile cancer are very common and can be caused by other conditions; having them does not definitely mean you have penile cancer, but it's important to get them checked by a GP. Cancer Research UK calls penile cancer rare.

Ask for an urgent GP appointment or get help from NHS 111 if you have gonorrhoea, or think you might, and your eyes are red, itchy or painful, or you have pus that sticks to your eyelashes, a high temperature, joint pain or swelling, or a bumpy, spotty or blotchy rash. The NHS says these can be signs of a more serious gonorrhoea infection that needs to be treated quickly.

In Scotland, NHS inform says a discharge from the end of the penis could mean an STI, and to contact your local sexual health service for advice. It says to phone 111 if you become very ill and have severe pain, a high temperature, or nausea and/or vomiting.

The table below shows how to get urgent advice in each UK nation.

Call 999 or go to A&E if your or your child's foreskin is pulled back and cannot go back to its original position over the end of the penis. This is paraphimosis, and the NHS calls it a medical emergency.

Try not to be embarrassed: the NHS says the doctor or nurse will be used to talking about these symptoms. For penis lumps or spots, it says they will look at your penis, usually ask about your health, your symptoms and when you last had sex, and may take a blood or pee sample or wipe a cotton bud over the tip of your penis to test for infections.

Where can you get help in the UK?

Anywhere in the UK, call 999 in a life-threatening emergency. The NHS in England says A&E is for serious injuries and life-threatening emergencies, and not to drive yourself there: ask someone to drive you, or call 999 for an ambulance.

For a problem with your penis, Northern Ireland's nidirect says to go to your GP or a sexual health clinic, and the NHS in England says the same for balanitis.

• England: clinics are free and confidential unless staff think someone is at risk of harm, and even then they'll talk to you first; you don't usually need a GP referral or appointment, but contact the clinic first.
• Scotland: services are free and your GP won't be told without your permission; phone a service for an appointment, or book online where offered.
• Wales: clinics are free and confidential on the same terms as England; many offer a walk-in service, where you don't need an appointment.
• Northern Ireland: clinics are free and confidential unless you share something that indicates someone is at risk; you don't need a doctor's referral, but in most cases you need an appointment.