Epididymitis can be caused by a sexually transmitted infection, but it is not always an STD. In men under 35, chlamydia and gonorrhea are the most common causes. In men over 35, the condition is more often triggered by urinary tract bacteria, prostate issues, or physical strain. The distinction matters because the cause determines both the treatment and whether a sexual partner needs to be notified.
Why Age Is the Biggest Clue
The epididymis is a coiled tube behind each testicle that stores and transports sperm. When it becomes inflamed, the cause almost always traces back to bacteria that traveled there from somewhere else in the urinary or reproductive tract. Which bacteria are responsible depends heavily on age and sexual activity.
In sexually active men between 14 and 35, chlamydia and gonorrhea account for the majority of cases. These bacteria enter through the urethra during sex and migrate backward through the reproductive tract until they reach the epididymis. This is the scenario where epididymitis is directly linked to an STI, and it means any recent sexual partners need testing and likely treatment as well.
In men over 35, the picture shifts. The most common cause becomes infected urine flowing backward into the ejaculatory ducts, typically because an enlarged prostate partially blocks normal urine flow. The bacteria involved are the same gut organisms that cause urinary tract infections, not sexually transmitted ones. This type of epididymitis has nothing to do with sexual activity.
There’s one important exception to the age rule: men of any age who practice insertive anal intercourse are at higher risk for epididymitis caused by intestinal bacteria, regardless of whether an STI is also present.
Non-Infectious Causes
Not every case involves bacteria at all. Urine can flow backward into the epididymis during heavy lifting or intense straining, especially when the bladder is full. This causes chemical irritation rather than infection. The inflammation feels the same, but antibiotics won’t help because there’s no bacterial cause.
Other non-infectious triggers include direct groin trauma, recent urinary procedures like catheter insertion, and, rarely, viral infections such as mumps. Tuberculosis can also cause epididymitis in rare cases. Men with anatomical differences in the urinary tract, an uncircumcised penis, or a weakened immune system face higher risk for both infectious and non-infectious forms.
How It Feels
The hallmark symptom is pain and swelling on one side of the scrotum that builds over days. This gradual onset is what distinguishes epididymitis from testicular torsion, which causes sudden, severe pain and is a surgical emergency. With epididymitis, the pain often starts mild and worsens, and you may also notice warmth, redness, or a low fever. Some men experience burning during urination or unusual discharge, particularly when the cause is an STI.
If scrotal pain comes on suddenly and severely, that warrants immediate medical attention to rule out torsion, where the blood supply to the testicle gets cut off.
How It’s Diagnosed
A urine test and a urethral swab are the primary tools. The urine test checks for bacteria associated with urinary tract infections, while the swab is tested specifically for chlamydia and gonorrhea. In some cases, an ultrasound of the scrotum is used to confirm inflammation in the epididymis and rule out torsion or an abscess. The test results determine whether the cause is an STI or something else, which directly shapes treatment.
Treatment and Recovery Timeline
Antibiotics are the standard treatment when bacteria are the cause, with the specific prescription depending on whether the infection is sexually transmitted or urinary in origin. Most men start feeling better within two to three days of starting antibiotics, but full resolution of pain and swelling can take several weeks. If symptoms don’t improve within 72 hours, a follow-up visit is needed because the initial antibiotic choice may not be covering the right bacteria.
During recovery, the CDC recommends bed rest with the scrotum elevated, ice packs, and over-the-counter anti-inflammatory pain relievers. An athletic supporter helps reduce discomfort from movement. You should avoid heavy lifting and sexual activity until the infection has fully cleared.
What Happens if It Goes Untreated
Leaving epididymitis untreated raises the risk of serious complications. An abscess can form in the scrotum, requiring drainage. The inflammation can cut off blood supply to the testicle, causing tissue death. Chronic epididymitis, where pain persists for three months or longer, is another possible outcome. Perhaps most concerning for younger men, untreated infection can scar the epididymis and impair fertility, potentially on a permanent basis.
When Partners Need Testing
If your epididymitis is caused by chlamydia or gonorrhea, any sexual partners from the preceding 60 days should be tested and treated. Both infections frequently produce no symptoms in partners, especially in women, so a lack of symptoms doesn’t mean the infection isn’t present. Treatment for both partners prevents reinfection and stops the spread. If the cause is urinary tract bacteria or a non-infectious trigger, partner notification isn’t necessary.