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Non-specific urethritis (NSU) is one of the most common sexually transmitted infections (STIs) in men. If it’s left untreated it can cause arthritis. 

It’s also known as non-gonococcal urethritis (NGU) when not caused by gonorrhoea.

Urethritis means inflammation of the urethra. That's the tube inside the penis that urine comes down.

Non-specific means the exact cause of the inflammation isn’t known, but it's caused by bacteria (often chlamydia) picked up from a partner’s mouth, vagina, rectum or penis during sex.

This page only covers NSU in men.

Women can also contract NSU but it can be harder to diagnose in women as it does not cause many symptoms.

NSU symptoms

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There may be no symptoms, but up to three weeks after becoming infected a man might experience the following:

  • a whitish discharge from his penis 
  • peeing frequently 
  • pain or burning when peeing
  • irritation and soreness at the tip of his penis.

How NSU is passed on

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NSU is usually caused by bacteria.

They live inside a partner’s mouth, vagina, penis or rectum and get into a man’s penis when he has unprotected oral, vaginal or anal sex.

He might also carry the bacteria on his fingers to his penis after touching an infected part of his own or someone else’s body.

Using condoms cuts the risk of NSU, which can also be caused by unprotected oral sex. Sometimes NSU is inflammation caused by friction from masturbation and sex, or even a reaction to things like soap.

If a man has HIV, untreated NSU could make it more likely he will pass on HIV during unprotected sex. But if HIV drugs have made his viral load undetectable then NSU and other infections don’t appear to make him more likely to pass on HIV.

NSU tests and treatment

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There’s a urine test for NSU, or a sample can be taken from the opening of the penis using a swab (a small cotton bud). This might be uncomfortable for a second or two.

A course of antibiotics will cure NSU. Sex should be avoided until the treatment is finished to avoid passing it on. Sexual partners also need to be checked and treated – a clinic can contact them anonymously.

Untreated NSU sometimes causes serious problems such as arthritis.

Most people get tested and treated for infections like NSU at sexual health (GUM) clinics. It's free and confidential and no-one else, including your GP, will be told about your visit. Some GP surgeries also test for and treat these infections.

The more people you have sex with (especially unprotected sex), the more chance you have of getting infections like NSU. You can have them without knowing, so regular check-ups are a good idea, especially if you're starting a new relationship and/or you want to stop using condoms with your partner.