References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
Non-gonococcal urethritis (NGU) is inflammation of the urethra in men caused by something other than gonorrhoea. It’s one of the most common reasons men visit sexual health clinics, typically presenting as discharge from the penis and pain when urinating. Chlamydia is the most common cause, but mycoplasma genitalium, ureaplasma, and other organisms can also be responsible.
If you’ve been told you have NGU, or you have discharge and burning that isn’t gonorrhoea, this guide explains the causes, testing, and treatment.
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What Causes NGU?
| Cause | How Common | Test Available? |
|---|---|---|
| Chlamydia trachomatis | 30-50% of NGU cases | Yes (NAAT urine test) |
| Mycoplasma genitalium | 10-25% | Yes (specific NAAT) |
| Ureaplasma urealyticum | 5-15% | Yes (PCR) |
| Trichomonas vaginalis | 1-5% | Yes (NAAT) |
| Herpes simplex virus | 2-3% | Yes (swab) |
| Adenovirus | 2-4% | Sometimes |
| Unknown / idiopathic | 20-30% | No identifiable cause |
In 20-30% of NGU cases, no specific organism is identified despite testing. These cases usually still respond to antibiotic treatment.
Symptoms
- Clear, white, or slightly cloudy discharge from the penis (often most noticeable first thing in the morning)
- Burning or stinging when urinating
- Irritation or itching at the tip of the penis
- Increased frequency of urination
- Mild pain or discomfort in the urethra
Symptoms are typically milder than gonorrhoea. Gonorrhoea tends to cause thicker, more profuse, yellow-green discharge with more significant pain.
How Is NGU Diagnosed?
- Urine test (NAAT): Checks for chlamydia, gonorrhoea, and sometimes Mgen and trichomoniasis
- Urethral swab: A thin swab inserted into the urethra to collect cells. Used when urine test is inconclusive or to check for specific organisms
- Microscopy: Examining urethral fluid under a microscope can confirm inflammation (white blood cells) even before the organism is identified
NGU is diagnosed when urethritis is confirmed but gonorrhoea is ruled out. Further testing then identifies the specific cause.
Treatment
Treatment depends on the identified cause:
If chlamydia is the cause
Doxycycline 100mg twice daily for 7 days (now preferred over single-dose azithromycin)
If the cause is unknown (empirical treatment)
Doxycycline 100mg twice daily for 7 days is the standard first-line treatment for NGU, as it covers chlamydia and many other possible causes.
If symptoms persist after doxycycline
Test specifically for Mycoplasma genitalium (with macrolide resistance testing). Treatment may require azithromycin (extended course) or moxifloxacin.
If trichomoniasis is identified
Metronidazole 400mg twice daily for 5-7 days
Avoid sex for 7 days after starting treatment and until your partner has been treated. Sexual partners should be tested and treated simultaneously.
Can NGU Come Back?
Recurrent NGU (symptoms returning after treatment) affects 10-20% of men. Common reasons:
- Reinfection from an untreated partner
- Mycoplasma genitalium not covered by initial treatment
- Antibiotic resistance (especially in Mgen)
- Non-infectious causes (irritation from soaps, catheterisation)
If NGU recurs, your clinic will typically test for Mgen and ureaplasma specifically and may try a different antibiotic regimen.
Read more: What is chlamydia? | Mycoplasma genitalium | Penile discharge guide
Frequently Asked Questions
Is NGU an STI?
Usually yes. The most common causes (chlamydia, Mgen) are sexually transmitted. However, some cases of NGU have non-sexual causes (chemical irritation, catheter use). It’s treated as an STI for partner notification purposes.
Can women get NGU?
The term NGU specifically refers to male urethritis. Women can get the same infections (chlamydia, Mgen) but they cause cervicitis or PID rather than urethritis. Partners of men with NGU should be tested.
How long does NGU take to clear?
Symptoms usually improve within 2-3 days of starting antibiotics. Complete the full course even if you feel better. If symptoms haven’t resolved after 2 weeks, return to your clinic.
Related reading
- Multi-Site STI Testing: Genital, Rectal and Throat
- What Is Gonococcal Arthritis?
- What Is Mycoplasma Genitalium?
- What Is Super Gonorrhoea?
- Can You Get Chlamydia From Kissing?
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
