GPAtlas🧭 When to suspect
Non-gonococcal urethritis (NGU) is inflammation of the urethra in which gonorrhoea has been excluded – confirmed by an excess of polymorphonuclear leucocytes in the anterior urethra without Gram-negative intracellular diplococci.
It is one of the commonest reasons men attend sexual-health services, typically presenting with:
• Urethral discharge
• Dysuria
• Penile-tip irritation
It can be asymptomatic.
Suspect it in any sexually active man (or person with a penis), particularly with:
• A new partner
• Multiple partners
• Condomless sex
• Chlamydia trachomatis is the commonest identified cause.
• Mycoplasma genitalium is increasingly important and is the dominant cause of persistent or recurrent NGU.
• In a large minority (~10–45%) no organism is found (idiopathic NGU), and some of these are non-infective.
Because gonococcal and non-gonococcal urethritis are indistinguishable on symptoms, NGU is a diagnosis made only after gonorrhoea has been excluded – so testing is essential.
The GP should:
• Recognise the syndrome
• Exclude the red flags (epididymo-orchitis, systemic illness, reactive arthritis)
• Test (including for gonorrhoea, to confirm this really is NGU)
• Route the patient into sexual-health care – where microscopy confirmation, a full STI screen, partner notification and resistance-guided treatment can all happen
Comprehensive care is the goal, not a quick prescription.
| Cause of NGU | Notes |
|---|---|
| Chlamydia trachomatis | The commonest identified cause (~20–50% of NGU). |
| Mycoplasma genitalium | • ~15–25% • The key driver of persistent/recurrent NGU • Needs resistance-guided treatment |
| Ureaplasma urealyticum | Inconsistent association – usually only at high organism load. |
| Trichomonas vaginalis | • Uncommon in the UK (< 2%) • Consider in men who have sex with women, especially where locally prevalent |
| Adenovirus or herpes simplex | • Viral – often with meatitis, conjunctivitis or ulceration • Usually self-limiting |
| Haemophilus spp. or Neisseria meningitidis | • Recognised pathogens (new in 2026) • May follow condomless oral sex |
| Organism-negative (idiopathic) | • No pathogen found in ~10–45% • Some non-infective (trauma, foreign body, stricture, chemical irritation) |
Source: BASHH NGU 2026
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