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.
Testicular pain can be caused by several things, including STIs. Chlamydia and gonorrhoea can cause epididymitis (inflammation of the tube behind the testicle), which leads to pain, swelling and discomfort. But testicular pain has other causes too, some of which are medical emergencies. Sudden severe testicular pain should always be assessed urgently.
Here’s what to know.
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Causes of Testicular Pain
| Cause | Features | Urgency |
|---|---|---|
| Testicular torsion | Sudden severe pain, often with nausea; usually in adolescents/young men | Medical emergency — minutes matter |
| Epididymitis (STI-related) | Gradual pain and swelling, often one side, sometimes discharge | Same-day assessment |
| Orchitis | Testicular pain, sometimes after mumps or other infection | Same-day assessment |
| Varicocele | Dull ache, feels like “bag of worms” | Routine review |
| Hydrocele | Painless swelling | Routine review |
| Testicular cancer | Painless lump, sometimes dull ache | Urgent review |
| Trauma | Obvious cause | Assess based on severity |
| Referred pain (e.g. kidney stones) | Pain radiates from elsewhere | Assess based on cause |
STI-Related Testicular Pain
The main STI cause of testicular pain is epididymitis, usually from chlamydia or gonorrhoea. Features include:
- Pain and swelling, typically on one side
- Gradual onset over days
- Sometimes urethral discharge
- Sometimes painful urination
- May radiate to the groin or lower abdomen
- Testicle often tender to touch
Untreated epididymitis can, rarely, affect fertility. Prompt antibiotic treatment is important.
Testicular Torsion: The Emergency
Testicular torsion is a twisting of the spermatic cord that cuts off blood supply to the testicle. It’s a surgical emergency — the testicle can be lost within hours if not treated. Features:
- Very sudden severe pain
- Often wakes you from sleep
- Nausea and vomiting
- Testicle may be swollen and higher than usual
- Most common in adolescents and young men
If you suspect torsion, go to A&E immediately. Do not wait.
When to Seek Help
Urgent (A&E):
- Sudden severe testicular pain
- Pain with nausea or vomiting
- Swelling with discoloration
- Trauma to the area with severe pain
Same-day clinic or GP:
- Gradual testicular pain over days
- Pain with discharge or dysuria
- Tender swollen testicle without emergency features
Routine appointment:
- Painless lump
- Mild ache or discomfort
- Swelling that feels like a bag of worms
Testing
If STI is suspected:
- Urine sample for chlamydia and gonorrhoea
- Examination by a clinician
- Sometimes ultrasound to rule out other causes
Treatment
- STI epididymitis — antibiotics covering chlamydia, gonorrhoea and mycoplasma
- Rest, scrotal support and pain relief
- Partners should be tested and treated
- Follow-up to ensure resolution
Read more: What is chlamydia? | What is gonorrhoea? | When to go to A&E
Frequently Asked Questions
Can chlamydia cause testicular pain?
Yes. Chlamydia is one of the main STI causes of epididymitis, particularly in younger men.
Will I know if I have testicular torsion?
Sudden severe pain, often with nausea, is a classic feature. If you’re unsure, go to A&E — torsion is a time-critical emergency.
Can testicular pain affect fertility?
Untreated serious causes (torsion, severe untreated infection) can affect fertility. Prompt diagnosis and treatment minimise this risk.
Related reading
- Blood Test for Syphilis, Hepatitis B and Hepatitis C
- Can You Have Chlamydia and Test Negative?
- Can You Test for STIs While on Your Period?
- Cold Sores vs Syphilis Sores: How to Tell the Difference
- Common STI Symptoms in Women
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.
