What is non-specific urethritis (NSU)?

NSU is inflammation of the urethra, the tube that carries pee out of your body, when the cause isn’t Gonorrhoea. Urethritis caused by Gonorrhoea is called gonococcal urethritis. Everything else is non-gonococcal urethritis (NGU), the name UK guidelines now use.

“Non-specific” describes the cause, not the symptoms. It used to mean doctors couldn’t name the germ, but today a cause is found in most cases.

NSU isn’t a mystery illness: in most cases, it’s caught through sex.

UK guidelines say urethritis is caught through sex in most cases. Causes include:

• Chlamydia: found in roughly a quarter to a half of men with NSU
• Mycoplasma genitalium: found in roughly 1 in 10 to 1 in 3
• Trichomonas: rare in the UK, causing under 2% of cases
• viruses: such as Herpes and adenovirus, a common virus that can be passed on through oral and anal sex

Other bacteria cause some cases. In 10% to 45% of men, no germ is found, and some cases may not be caused by an infection at all. Ureaplasma is common in men without NSU too, and UK guidelines don’t recommend testing for it.

Chlamydia and Mycoplasma genitalium are the most common causes, and both can be passed on. Read more in “4 infections you’ve never heard of: symptoms and risks”

Symptoms of NSU can include:

• pain or a burning feeling when you pee
• a white or cloudy discharge from the tip of the penis
• an irritated or sore tip of the penis
• itching or discomfort inside the penis

If NSU is caused by an STI, symptoms can take a few days or weeks to appear after sex. Some men have no symptoms at all, and many people with Chlamydia or Mycoplasma genitalium never notice anything. Needing to pee more often is more typical of a urine infection (UTI).

Pain when you pee and a discharge are the classic signs, but you can have NSU without them. Read more in “Penis discharge: do I have an STI?”

NSU is a diagnosis doctors make in people with a penis, based on symptoms from the penis. But the infections that cause it, such as Chlamydia and Mycoplasma genitalium, affect women too.

In women, these infections often cause no symptoms. When they do, they can cause bleeding after sex, and Chlamydia can also cause unusual discharge or pain when you pee. If they aren’t treated, they can spread to the womb and fallopian tubes, causing pelvic inflammatory disease (PID).

If your partner has NSU, get tested, even if you feel well.

A doctor confirms urethritis by looking for signs of inflammation:

• a swab from the urethra: the sample is checked under a microscope for white blood cells
• a lab urine test: some labs count the white blood cells in the first part of your pee instead

Your urine is also tested for Chlamydia, Gonorrhoea and Mycoplasma genitalium. If your symptoms carry on, you may be tested for Trichomonas too. For the most reliable results, try not to pee for 2 hours before you give a sample.

Finding the infection behind NSU is what decides your treatment. Read more in “How to test for Chlamydia: which sample you need and when”

UK guidelines recommend doxycycline, an antibiotic, taken twice a day for 7 days. A single dose of azithromycin is no longer recommended, because it can leave Mycoplasma genitalium resistant to treatment.

While you’re being treated:

• don’t have sex, including oral sex, until you and your partners have finished treatment and your symptoms have gone
• take every tablet, even if you feel better
• get checked again if your symptoms last 2 weeks or more after you start treatment

Symptoms usually go within a week or two. In 5% to 25% of men they don’t clear, or they come back, often because of Mycoplasma genitalium. In England in 2025, about two thirds of Mycoplasma genitalium samples tested were resistant to azithromycin.

Finish the course, and wait until your partners have been treated too.

Untreated NSU can lead to:

• epididymo-orchitis: painful swelling of the tube behind the testicle, and sometimes the testicle itself
• reactive arthritis: painful, swollen joints, sometimes with sore eyes. Reactive arthritis after an STI is more than 10 times as common in men as in women
• infections in partners: untreated Chlamydia leads to PID in about 1 in 6 women, which can affect fertility

Sudden, severe pain in a testicle is an emergency, so call 999 straight away. Do the same if testicle pain comes with feeling sick, being sick or tummy pain. Sudden pain can mean the testicle has twisted, which needs surgery quickly.

Yes. Because NSU is usually caught through sex, your current partners should be tested, and treated if an infection is found. If a specific infection such as Chlamydia is found, partners from further back may need testing too.

Telling a partner can feel awkward, but it protects their health and stops the infection being passed back to you.

If your partner isn’t treated, you can catch it again. Read more in “Can an STI come back after treatment?”

Better2Know offers:

• Comfort Screen: tests a urine sample for 8 infections, including Chlamydia, Gonorrhoea, Mycoplasma and Trichomonas, from 14 days after sex, with results in 2 days (3 days for the home test).
• Chlamydia and Gonorrhoea home test: a urine test for both infections, from 14 days after sex, with results in 2 days.
• Mycoplasma: a urine test, from 14 days after sex, with results in 5 days.
• Urine Analysis: Culture and Microscopy: checks a urine sample for bacteria and blood cells if you think you might have a urine infection, with results in 2 days.

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. You can book at one of our clinics. Not sure which test you need? Our Patient Care Team is available 24/7 on 020 7099 0955.

Is NSU an STI?

Usually, yes. UK guidelines say urethritis is caught through sex in most cases, most often from Chlamydia or Mycoplasma genitalium. That’s why partners are tested too.

How long does NSU take to clear up?

With antibiotics, symptoms usually go within a week or two. If they last 2 weeks or more after you start treatment, get checked again.

Can NSU come back?

Yes. You can catch an infection again from a partner who hasn’t been treated, and Mycoplasma genitalium sometimes survives the first antibiotic. Symptoms that don’t clear, or come back within 3 months, need another check.

NSU means urethritis that isn’t caused by Gonorrhoea. Despite the name, it’s usually caught through sex, most often from Chlamydia or Mycoplasma genitalium, and it’s usually treated with a week of antibiotics. Testing finds the cause, and treating your partners stops it being passed back to you.

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 25 September 2012 and was last updated on 1 October 2026.

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

Sources

1. NHS, Urethritis, reviewed 10 May 2023. https://www.nhs.uk/conditions/urethritis/
2. NHS, Chlamydia, reviewed 24 October 2024. https://www.nhs.uk/conditions/chlamydia/
3. NHS, Urinary tract infections (UTIs), reviewed 11 July 2025. https://www.nhs.uk/conditions/urinary-tract-infections-utis/
4. NHS, Epididymitis, reviewed 6 August 2024. https://www.nhs.uk/conditions/epididymitis/
5. NHS, Reactive arthritis, reviewed 16 December 2024. https://www.nhs.uk/conditions/reactive-arthritis/
6. NHS, Testicle pain, reviewed 26 June 2025. https://www.nhs.uk/symptoms/testicle-pain/
7. British Association for Sexual Health and HIV, National guideline on the management of non-gonococcal urethritis, 2026. https://www.bashh.org/_userfiles/pages/files/resources/ngu_2026.pdf
8. 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
9. British Association for Sexual Health and HIV, UK national guideline for the management of infection with Chlamydia trachomatis, 2026. https://www.bashh.org/_userfiles/pages/files/national_guideline_for_the_management_of_infection_chlamydia_trachomatis_2026.pdf
10. British Association for Sexual Health and HIV, Summary guidance on testing for sexually transmitted infections, 2023. https://www.bashh.org/_userfiles/pages/files/resources/bashh_summary_guidance_on_stis_testing_2023.pdf
11. British Association for Sexual Health and HIV, National guideline for the management of epididymo-orchitis, 2020. https://www.bashh.org/_userfiles/pages/files/resources/eo2020.pdf
12. British Association for Sexual Health and HIV, National guideline on the management of sexually acquired reactive arthritis, 2021. https://www.bashh.org/_userfiles/pages/files/resources/sara2021.pdf
13. UK Health Security Agency, Mycoplasma genitalium antimicrobial resistance surveillance (MARS) report 2025, 30 July 2026. https://www.gov.uk/government/publications/mycoplasma-genitalium-antimicrobial-resistance-surveillance-mars/mars-report-2025