Penis discharge: do I have an STI?

It can be. Unusual discharge is a common symptom of STIs such as Chlamydia and Gonorrhoea. But it can also be caused by other conditions, such as balanitis or thrush, and sometimes no cause is found.

You can’t tell the cause from the discharge alone, so the best thing to do is get tested rather than guess.

Some fluid from the penis is normal. Pre-ejaculate (pre-cum) is released when you’re aroused, and semen when you ejaculate. Smegma, a yellowish-white creamy substance, can build up under the foreskin if you don’t wash there every day.

Discharge that’s white, cloudy, yellow or green, thick, or smells bad isn’t normal, especially if you also have pain when you pee, itching or soreness.

• Chlamydia: white, cloudy or watery discharge from the tip of the penis, a burning feeling when you pee, and pain and swelling in the testicles. Most people with Chlamydia have no symptoms.
• Gonorrhoea: white, yellow or green discharge, burning pain when you pee, and sore testicles.
• Mycoplasma genitalium: discharge, pain when you pee, and redness or irritation of the penis. Most men with it are thought to have no symptoms.
• Trichomonas: discharge, pain when you pee or ejaculate, and needing to pee often. It’s an uncommon cause of discharge in UK men.
• Herpes: can sometimes cause inflammation inside the penis, with pain when you pee and sometimes sores.

Read more in “Why do I have green discharge coming out of my genitals?”

Urethritis is inflammation of the urethra, the tube that carries pee out of your body. Symptoms include pain or burning when you pee, white or cloudy discharge, and an irritated or sore tip of the penis, but it doesn’t always cause symptoms.

It’s usually caused by an STI. When it isn’t caused by Gonorrhoea, it’s called non-gonococcal urethritis (NGU), and the most common causes are Chlamydia and Mycoplasma genitalium. In 10% to 45% of cases, no cause is found. Urethritis is usually treated with antibiotics. Without treatment, it can lead to an infection in the testicles or reactive arthritis.

Balanitis

Balanitis is when the head of the penis is swollen, itchy and sore. It can cause a thick discharge from under the foreskin, bleeding around the foreskin, an unpleasant smell and pain when you pee. Causes include not washing properly, thrush, STIs such as Gonorrhoea or Chlamydia, and soaps, shower gels or condoms irritating the skin.

Thrush

Thrush can cause a white discharge like cottage cheese, irritation and redness around the head of the penis and under the foreskin, and an unpleasant smell. It isn’t classed as an STI. Read more in “Thrush or STI: how to know the difference”

UTIs

UTIs cause pain when you pee, needing to pee more often, and cloudy or smelly pee, but discharge isn’t a usual symptom. UTIs are less common in men, and a man with UTI symptoms should get urgent medical advice. Read more in “Is a UTI an STI? How to tell the difference”

• Call 999 if you have sudden, severe pain in a testicle, testicle pain with feeling sick, being sick or pain in your tummy, or testicle pain that has lasted more than an hour or continues when you’re resting. It could be a twisted testicle, which needs treating quickly.
• Get urgent medical advice if you have swollen testicles or a lump, symptoms of a UTI, or you can’t pee.

Men are usually tested for Chlamydia, Gonorrhoea, Mycoplasma and Trichomonas with a urine sample, using the first part of your pee. You’ll usually be asked not to pee for at least 2 hours beforehand. Tests for Chlamydia and Gonorrhoea are reliable from 2 weeks after sex. If you have symptoms, you don’t need to wait to get tested, but if you test within 2 weeks of sex, you may need a repeat test. Better2Know offers:

• Comfort Screen: tests a urine sample for 8 infections, including Chlamydia, Gonorrhoea, Mycoplasma, Trichomonas and Herpes 1 and 2, from 14 days after sex, with results in 2 days (3 days for the home test). You can book it at one of our clinics.
• Chlamydia and Gonorrhoea home test: a urine test from 14 days after sex, with results in 2 days.
• Urine Analysis: Culture and Microscopy: checks a urine sample for bacteria and blood cells if you think you might have a UTI, with results in 2 days.

Not sure which test you need? Our Patient Care Team is available 24/7 on 020 7099 0955.

Can you have an STI without any discharge?

Yes. Most people with Chlamydia have no symptoms, and up to 1 in 10 men with Gonorrhoea don’t notice any, so a test is the only way to know.

Should I avoid sex if I have discharge?

Yes, until you know the cause. If it’s an STI, don’t have sex, including oral sex, until you and your partner have finished treatment.

Can I treat discharge myself?

Not until you know the cause. Different infections need different treatments, and some, such as Gonorrhoea, need an antibiotic injection.

Discharge from the penis isn’t always an STI, but it often is, and you can’t tell by looking. A simple urine test can find the most common causes, so you can get the right treatment quickly.

Book a Comfort Screen at a clinic near you or order a home test kit. Our Patient Care Team is available 24/7 on 020 7099 0955.

Not in the UK? Choose your country from the selector at the top of the page for local tests and prices.

This article originally appeared on 22 November 2019 and was last updated on 1 October 2026.

This article is general information and not a substitute for personal medical advice.

Sources

1. NHS, Chlamydia, reviewed 24 October 2024. https://www.nhs.uk/conditions/chlamydia/
2. NHS, Gonorrhoea, reviewed 16 December 2024. https://www.nhs.uk/conditions/gonorrhoea/
3. Brook, Gonorrhoea. https://www.brook.org.uk/your-life/gonorrhoea/
4. British Association for Sexual Health and HIV, National guideline for the management of infection with Mycoplasma genitalium, 2025. https://www.bashh.org/_userfiles/pages/files/sonietal2025britishassociationofsexualhealthandhivnationalguidelineforthemanagementofinfectionwith.pdf
5. Brook, Mycoplasma genitalium (MG). https://www.brook.org.uk/your-life/mycoplasma-genitalium-mg/
6. NHS, Trichomoniasis, reviewed 16 July 2025. https://www.nhs.uk/conditions/trichomoniasis/
7. NHS, Urethritis, reviewed 10 May 2023. https://www.nhs.uk/conditions/urethritis/
8. British Association for Sexual Health and HIV, National guideline on the management of non-gonococcal urethritis (NGU), 2026. https://www.bashh.org/_userfiles/pages/files/resources/ngu_2026.pdf
9. NHS, Balanitis, reviewed 30 May 2023. https://www.nhs.uk/conditions/balanitis/
10. NHS, Thrush in men and women, reviewed 28 July 2023. https://www.nhs.uk/conditions/thrush-in-men-and-women/
11. NHS, Urinary tract infections (UTIs), reviewed 11 July 2025. https://www.nhs.uk/conditions/urinary-tract-infections-utis/
12. NHS, Epididymitis, reviewed 6 August 2024. https://www.nhs.uk/conditions/epididymitis/
13. NHS, Testicle pain, reviewed 26 June 2025. https://www.nhs.uk/symptoms/testicle-pain/
14. Brook, Penises and testicles, updated 9 February 2023. https://www.brook.org.uk/your-life/penises-and-testicles/
15. Brook, Penis and testicles common questions. https://www.brook.org.uk/your-life/penis-and-testicle-faqs/
16. Brook, How to complete your STI test at home. https://www.brook.org.uk/your-life/how-to-complete-your-sti-test-at-home/
17. NHS, Sexually transmitted infections (STIs), reviewed 13 May 2024. https://www.nhs.uk/conditions/sexually-transmitted-infections-stis/