Epididymitis is a medical condition characterized by inflammation of the epididymis, a curved structure at the back of the testicle. Onset of pain is typically over a day or two. The pain may improve with raising the testicle. Other symptoms may include swelling of the testicle, burning with urination, or frequent urination. Inflammation of the testicle is commonly also present.

In those who are young and sexually active gonorrhea and chlamydia are frequently the underlying cause. In older males and men who practice insertive anal sex, enteric bacteria are a common cause. Diagnosis is typically based on symptoms. Conditions that may result in similar symptoms include testicular torsion, inguinal hernia, and testicular cancer. Ultrasound can be useful if the diagnosis is unclear.

Treatment may include pain medications, NSAIDs, and elevation. Recommended antibiotics in those who are young and sexually active are ceftriaxone and doxycycline. Among those who are older, ofloxacin may be used. Complications include infertility and chronic pain. People aged 15 to 35 are most commonly affected, with about 600,000 people within this age group affected per year in the United States.