Pain in one testicle is common and usually caused by something treatable, but in rare cases it signals an emergency. The cause can range from a minor strain or infection to a twisted spermatic cord that needs surgery within hours. Understanding the type of pain you’re feeling, how fast it came on, and what else is happening in your body will help you figure out whether you can manage it at home or need to get to an emergency room.
Sudden, Severe Pain Could Be Torsion
Testicular torsion happens when the spermatic cord (the structure that suspends each testicle and supplies its blood) twists on itself, cutting off blood flow. It typically hits without warning: intense, one-sided pain that comes on within minutes, often with nausea or vomiting. On examination, the affected testicle may sit higher than normal because the twisted cord shortens it upward.
Torsion is a time-sensitive emergency. A systematic review of over 1,200 patients found that when surgery happens within the first 6 hours of pain, the testicle is saved 97% of the time. Between 7 and 12 hours, the salvage rate drops to about 79%. After 24 hours, fewer than half of testicles survive. If you’re experiencing sudden, severe scrotal pain, especially with nausea or a testicle that looks or feels out of position, go to the emergency room immediately.
Infection of the Epididymis
The most common cause of gradual-onset testicular pain in young and middle-aged adults is epididymitis, an infection or inflammation of the epididymis, the coiled tube that sits behind each testicle and carries sperm. The pain typically builds over a day or two rather than hitting all at once, and the back or bottom of the affected testicle feels swollen and tender. You might also notice redness, warmth, or pain when urinating.
In sexually active men under 35, the infection is most often caused by sexually transmitted bacteria like chlamydia or gonorrhea. In older men, the culprit is more commonly a urinary tract bacterium, particularly when there’s an underlying issue like an enlarged prostate or a recent urological procedure. Either way, epididymitis is treated with antibiotics, and most people start feeling better within a few days of starting treatment, though the swelling can linger for weeks.
Varicocele: A Dull, Aching Pain
If your pain is more of a dull ache that worsens after standing for a long time or physical activity, a varicocele is a likely explanation. A varicocele is essentially a varicose vein inside the scrotum. Valves inside the veins of the spermatic cord stop working properly, blood pools, and the veins gradually swell. About 15% of adult men have one, and they show up on the left side far more often than the right.
Varicoceles are graded by size. The smallest (Grade I) can only be detected during a specific straining maneuver. Grade II varicoceles can be felt during a regular exam. The largest (Grade III) are visible through the skin and often described as looking or feeling like a bag of worms. Most varicoceles don’t require treatment, but if the ache is persistent or the varicocele is affecting fertility, a minor procedure can redirect blood flow away from the swollen veins.
Pain That Isn’t Coming From the Testicle
Sometimes the testicle itself is perfectly healthy, but pain from somewhere else in the body shows up there. This is called referred pain, and it happens because the testicles share nerve pathways with structures in the abdomen and groin.
Two common culprits stand out. A kidney stone passing through the ureter (the tube connecting the kidney to the bladder) can cause sharp, radiating pain that reaches the scrotum, groin, or lower back. An inguinal hernia, where a loop of intestine pushes through a weak spot in the abdominal wall near the groin, can create a heavy, aching sensation in the testicle on the same side. In both cases, treating the underlying problem resolves the testicular pain.
Trauma and Injury
A direct hit to the groin, whether from sports, a fall, or an accident, can cause bruising, swelling, and significant pain. Most minor injuries heal on their own within a few days. The absence of visible swelling and bruising after an impact generally points to a less serious injury.
If pain after trauma is severe and out of proportion to what you’d expect, or if swelling continues to worsen, there’s a risk of testicular rupture, which requires surgical repair. Persistent or worsening symptoms after a groin injury warrant an urgent evaluation.
Testicular Cancer
Pain is not the typical first sign of testicular cancer. In about 90% of cases, men notice a painless lump on the testicle or generalized swelling before they feel any discomfort. That said, some testicular cancers do cause a dull ache or sense of heaviness. Any hard lump or noticeable change in the size or shape of a testicle deserves a medical evaluation, even if it doesn’t hurt. Testicular cancer has very high cure rates when caught early.
Post-Vasectomy Pain
If you’ve had a vasectomy, chronic scrotal pain is an uncommon but real possibility. About 5% of men develop what’s known as post-vasectomy pain syndrome, a persistent ache in one or both testicles that can start weeks to years after the procedure. First-line treatment typically involves anti-inflammatory medications, pelvic floor physical therapy, and sometimes nerve-targeting pain medications. Approaches like acupuncture or biofeedback help some men as well.
What to Do About Mild Pain
If the pain is mild, came on gradually, and you don’t have nausea, vomiting, fever, or visible swelling, you can try managing it at home for a day or two. Supportive underwear (briefs rather than boxers) reduces movement and takes pressure off the area. Applying an ice pack wrapped in a cloth for 15 to 20 minutes at a time can reduce swelling. Over-the-counter anti-inflammatory pain relievers can help with both pain and inflammation. Avoid strenuous exercise or heavy lifting until the discomfort settles.
If the pain doesn’t improve within a couple of days, gets worse, or comes with any new symptoms like fever, swelling, a lump, or difficulty urinating, get it checked. Testicular pain has a wide range of causes, and most of them respond well to treatment once correctly identified.