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.
Unusual discharge is one of the most common symptoms of sexually transmitted infections, though it’s important to remember that discharge alone doesn’t diagnose an STI. Different infections cause different types of discharge, and some STIs cause no discharge at all. Here’s a practical guide to help you recognise when something needs investigating.
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Normal vs Abnormal Discharge
Most people have some normal discharge. It’s usually:
- Clear or slightly milky
- Minimal odour
- Varies with the menstrual cycle (in women)
- No itching, pain or burning
Changes from your usual pattern — in colour, smell, consistency or amount — can signal infection.
Discharge by Condition
| Condition | Discharge Type | Other Symptoms |
|---|---|---|
| Chlamydia | Often none; sometimes thin, watery | Burning when urinating; often silent |
| Gonorrhoea | Yellow or green, thicker | Pain on urination, bleeding |
| Trichomoniasis | Frothy, yellow-green, foul-smelling | Itching, burning |
| Bacterial vaginosis | Thin, greyish-white, fishy odour | Usually no itching |
| Yeast infection | Thick, white, clumpy | Intense itching |
| Herpes | Not typical; lesions cause other symptoms | Painful blisters and ulcers |
Discharge in Men
Men usually don’t have normal discharge from the penis. Any discharge is generally abnormal:
- Clear or milky — often chlamydia
- Yellow or green — often gonorrhoea
- Thick and white — possibly non-gonococcal urethritis
Penile discharge warrants prompt STI testing.
Discharge From the Anus
Rectal discharge can be a sign of rectal STI, particularly after receptive anal sex. It can also come from other conditions including haemorrhoids or inflammatory bowel disease. LGV (a severe form of chlamydia) often causes rectal symptoms including bloody or mucous discharge.
What to Do If You Notice Unusual Discharge
- Don’t panic — many causes are easily treated
- Contact a sexual health clinic or GP
- Avoid sex until you’ve been assessed
- Don’t douche or use products that might mask symptoms
- Be ready to answer questions about recent sexual activity
Important Reminder
Most discharge symptoms have several possible causes. Appearance alone doesn’t give a definitive diagnosis. Proper testing is needed for accurate treatment.
Read more: Vaginal infections | What is chlamydia? | What is gonorrhoea?
Frequently Asked Questions
Can I tell which STI I have from the discharge?
Not reliably. Appearance gives clues but testing is needed for a proper diagnosis.
Is discharge always a sign of an STI?
No. Many non-STI causes exist, particularly for vaginal discharge. Common causes include BV, yeast and hormonal changes.
Should men with discharge always test for STIs?
Yes. Penile discharge is unusual and almost always warrants investigation.
Related reading
- Cold Sores vs Syphilis Sores: How to Tell the Difference
- Do STIs Always Have Symptoms?
- How Different STIs Affect Vaginal Discharge
- How to Identify Syphilis Sores (Chancres)
- Is My Rash From HIV or Something Else?
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.
