NGU and NSU – non-gonococcal and non-specific urethritis

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Key points

  • NGU and NSU can be caused by several STIs.
  • NGU/NSU is diagnosed by a swab test and/or checking a urine sample.
  • NGU and NSU are treated with a course of antibiotics.

Urethritis is an inflammation of the urethra, the tube through which urine (and, in men, semen) passes. This inflammation can be caused by several sexually transmitted infections.

Non-gonococcal urethritis (NGU) refers to urethritis that is not caused by gonorrhoea (Neisseria gonorrhoeae). Most commonly, NGU is caused by chlamydia (Chlamydia trachomatis) and can affect both men and women. Another term, non-specific urethritis (NSU) means that urethritis is neither caused by gonorrhoea nor chlamydia. NSU can have some non-sexual causes, such as irritation from a catheter or soap.

The terms NGU and NSU are often used interchangeably, although they have slightly different meanings. If left untreated, NGU/NSU can cause inflammation of the eyes and joints, and can increase the likelihood of passing on HIV. In very rare cases NGU/NSU can lead to reduced fertility.


NGU and NSU are usually caused by an infection which has been passed on during unprotected anal, oral and vaginal sex. Very rarely NSU can be caused by excessive friction during masturbation or sex, or an allergic reaction to soap or detergent.

In a person with HIV who is not taking HIV treatment, untreated NGU/NSU may make them more infectious. This is because untreated sexually transmitted infections can increase HIV viral load in genital fluids. However, if the person with HIV is taking effective HIV treatment and has an undetectable viral load, they will not pass HIV on. NGU/NSU will not make a difference to this.

In an HIV-negative person, having NGU/NSU can make it more likely that they will be infected with HIV if they are exposed to the virus.


Using a condom for anal, oral or vaginal sex is an effective way of avoiding the infections which cause NGU/NSU or passing NGU/NSU on to somebody else. You are also advised to avoid sharing sex toys. If you do share them, wash them or cover them with a new condom before anyone else uses them.

People who are sexually active are advised to have regular check-ups where they will be tested for NGU/NSU and other sexually transmitted infections. Most HIV treatment centres have an associated sexual health clinic where free and confidential treatment can be obtained without referral from your GP or your HIV doctor.


Symptoms of NGU/NSU may take weeks to develop, although some irritants, such as soap, can cause symptoms to occur almost immediately. However, some people’s symptoms may be so mild that they are not noticed by themselves or by their sexual partners.

"Using a condom is an effective way of avoiding the infections that cause urethritis."

When symptoms do occur, they normally consist of pain or a burning sensation when passing urine, a white or cloudy discharge which may be particularly noticeable first thing in the morning, and/or irritation at the tip or opening of the penis. Needing to pass urine more often can also be a symptom.


A general sexual health check-up at a genitourinary medicine (GUM) or a sexual health clinic, will include a test for NGU/NSU. GUM clinics are free, confidential and open access. Some HIV clinics also offer sexual health screening.

For men with symptoms, NGU/NSU is diagnosed by either a swab test on the tip of the penis or by checking a urine sample, or often both. In many cases it will be possible to tell instantly if NGU is present, but it can take up to a week for tests to show if chlamydia is present.

Women are only tested when their partner has NGU. A chlamydia test can be done on a vaginal swab taken by the woman herself, or a swab from the cervix (neck of the womb) taken by a doctor or nurse.


NGU/NSU is treated with antibiotics. Normally this consists of a seven-day course of doxycycline. However, a five-day course of azithromycin or a seven-day course of ofloxacin may also be prescribed.

It is important to take all your tablets to ensure that the infection has been cleared from your body.

Symptoms may last for a few days after taking azithromycin as the antibiotic takes time to work.



Any perceptible, subjective change in the body or its functions that signals the presence of a disease or condition, as reported by the patient.



Chlamydia is a common sexually transmitted infection, caused by bacteria called Chlamydia trachomatis. Women can get chlamydia in the cervix, rectum, or throat. Men can get chlamydia in the urethra (inside the penis), rectum, or throat. Chlamydia is treated with antibiotics.

sexually transmitted infections (STIs)

Although HIV can be sexually transmitted, the term is most often used to refer to chlamydia, gonorrhoea, syphilis, herpes, scabies, trichomonas vaginalis, etc.


How well something works (in real life conditions). See also 'efficacy'.


Antibiotics, also known as antibacterials, are medications that destroy or slow down the growth of bacteria. They are used to treat diseases caused by bacteria.

When NGU/NSU is diagnosed, you may be given an opportunity to speak to a health adviser who can give you information about safer sex and how to avoid acquiring or passing on sexually transmitted infections. Health advisers may also ask you to help them, where possible, to contact your sexual partners so they can be tested and treated too. This in turn, is intended to prevent you from becoming re-infected through continuing to have sex with someone who is themselves infected.

You may be asked to return two or three weeks later for a test to see that you have been cured, and sometimes there may be a follow-up over the phone. You are likely to be advised not to have sex (even with a condom) until your treatment period has finished and you are free of symptoms. This is to prevent re-infection.

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