Acute epididymitis is inflammation of the epididymis, a tube at the back of the testicle that stores and carries sperm. It typically causes pain and swelling on one side of the scrotum that develops over several days. The pain is usually worst at the back of the testicle. In some cases, the testicle itself may also become inflamed.

Acute epididymitis is usually caused by an infection. In sexually active men, especially younger guys, it's often due to sexually transmitted infections like chlamydia or gonorrhea. For men who aren't sexually active, especially older men, it's more likely to be caused by bacteria from a urinary tract infection. Risk factors include recent urinary tract procedures, enlarged prostate, or other conditions that affect urine flow.

The main symptom is gradual onset of pain on one side of the scrotum, which may be swollen and tender. You might also have pain when urinating, a frequent urge to pee, or discharge from the penis if you have a related urinary tract or sexually transmitted infection. Fever and feeling generally unwell can occur in more severe cases. If you have sudden, severe scrotal pain, especially with nausea or vomiting, seek immediate medical attention as this could indicate a more serious condition like testicular torsion.

Doctors diagnose acute epididymitis based on symptoms and physical examination. They may also order urine tests or swabs to check for infections. Treatment usually involves antibiotics to clear the infection. Pain relievers, ice packs, and supportive underwear can help manage discomfort. Most cases improve within a few days of starting treatment, though swelling can take several weeks to fully resolve.

While uncomfortable, acute epididymitis is usually easily treated with prompt medical care.