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.
Blood in urine (haematuria) can be caused by some STIs, but it’s more commonly caused by urinary tract infections, kidney stones, or other non-sexual conditions. If you’ve noticed pink, red, or brown-tinged urine and you’re wondering whether it could be an STI, this guide covers which infections can cause it and what else might be responsible.
Any blood in your urine should be checked by a doctor, regardless of the cause. Don’t assume it’s harmless.
Concerned about an STI? Get a discreet home test kit
STIs That Can Cause Blood in Urine
Most STIs don’t directly cause blood in the urine, but a few can when they infect the urinary tract:
Chlamydia
Chlamydia can infect the urethra (the tube urine passes through), causing urethritis. This can occasionally lead to blood in the urine, though it’s more common to see blood-tinged discharge or burning without visible blood. Chlamydia is a more likely cause of blood in urine in men than women.
Gonorrhoea
Gonorrhoea causes more pronounced urethral inflammation than chlamydia. Blood in urine or blood-streaked discharge is more common with gonorrhoea, particularly in men. It’s often accompanied by thick yellow-green discharge and significant pain when urinating.
Trichomoniasis
In women, trichomoniasis can cause inflammation of the urethra and bladder, occasionally leading to blood-tinged urine. It’s more likely to cause other symptoms first: frothy discharge, itching, and pain during urination.
Genital herpes
During a herpes outbreak, sores near the urethral opening can bleed, causing blood to mix with urine. This is more a case of blood contaminating the urine rather than blood originating from the urinary tract itself.
More Common Causes of Blood in Urine
| Cause | Other Symptoms | How Common |
|---|---|---|
| Urinary tract infection (UTI) | Burning, frequency, cloudy urine, pelvic pain | Very common |
| Kidney stones | Severe flank pain, nausea, blood in urine | Common |
| Vigorous exercise | Blood after intense activity, resolves with rest | Common (especially runners) |
| Kidney infection (pyelonephritis) | Fever, back pain, nausea, smelly urine | Moderate |
| Menstruation contamination | Blood during period mixed with urine sample | Common (women) |
| Prostate problems (men) | Difficulty urinating, weak stream, frequency | Common in older men |
| Bladder cancer | Painless blood, often in older adults | Uncommon but serious |
UTIs are by far the most common cause of blood in urine, especially in women. If you have blood in your urine with burning and frequency but no discharge, a UTI is the most likely explanation.
When Blood in Urine Might Be an STI
Consider an STI as a possible cause if:
- You’ve had unprotected sex with a new partner recently
- Blood in urine is accompanied by unusual discharge
- You have pain when urinating AND discharge (the combination is key)
- A partner has told you they have an STI
- Standard UTI treatment hasn’t resolved your symptoms
If none of these apply, a non-STI cause is much more likely.
What to Do If You Notice Blood in Your Urine
- Don’t panic but don’t ignore it. Most causes are treatable
- See your GP for a urine test. They’ll check for infection, blood cells, and protein
- Get an STI test if you have any risk factors (new partner, unprotected sex, discharge)
- Note other symptoms: Is there pain? Discharge? Fever? When did it start? This helps your doctor narrow down the cause
Order a home STI test for peace of mind alongside a GP visit.
Read more: UTI vs STI | Pain when urinating | What is chlamydia?
Frequently Asked Questions
Can chlamydia cause visible blood in urine?
Occasionally, but it’s uncommon. Chlamydia more commonly causes mild urethral irritation without visible blood. If chlamydia has progressed to cause significant inflammation, blood-tinged urine or discharge is possible. A urine test can check for both chlamydia and blood.
Is blood in urine always serious?
Not always, but it should always be investigated. Common causes like UTIs and exercise-related haematuria are easily treated. Rarer causes like bladder cancer are serious but uncommon. The only way to know the cause is to see a doctor and get tested.
Can period blood be mistaken for blood in urine?
Yes. During menstruation, blood can mix with urine and look like haematuria. If you notice blood in your urine during your period, wait until your period ends and check again. If blood persists, see your GP.
Should I go to A&E for blood in my urine?
Go to A&E if you have blood in your urine with severe pain (possible kidney stone or torsion), high fever (possible kidney infection), or inability to urinate. Otherwise, a GP appointment within a few days is appropriate.
Related reading
- A to Z of Sex: Sexual Health Terms Explained
- Alcohol and HIV: What You Need to Know
- Anxiety and HIV: Coping and Getting Support
- Are All STIs Curable?
- Blood Problems and HIV: Anaemia, Low Platelets and More
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.
