Testicular swelling or pain
Sudden severe pain in one testicle needs urgent assessment — it can be caused by testicular torsion (the testicle twisting), which is a surgical emergency. Testicles can also swell for other reasons including infection, a hernia, a fluid-filled cyst, or a hydrocele.
When to get medical help
Use NHS 111 online, call 111, or contact your GP if:
- Painless lump or swelling in a testicle — always get this checked
- Aching, dragging pain that has come on gradually
- Swelling with a fever or discharge from the penis — could be infection
Call 999 or go to A&E if you have sudden severe pain in a testicle, especially with nausea or vomiting, or if the testicle looks red and swollen. Go to A&E straight away — testicular torsion needs treatment within hours to save the testicle.
Further information
This page provides general information only. It is not a diagnosis and is not a substitute for professional medical advice.