A sore testicle usually comes from one of a handful of causes, ranging from a minor strain to a condition that needs same-day medical attention. The key factor is how the pain started. Sudden, severe pain is a potential emergency. A gradual ache that builds over days points to infection, a structural issue, or referred pain from somewhere else in the body.
Sudden Severe Pain: Torsion Is the Concern
Testicular torsion happens when the spermatic cord twists, cutting off blood flow to the testicle. The classic presentation is sudden, severe pain on one side along with nausea or vomiting. The affected testicle may ride higher than normal or sit at an unusual angle, and the skin around it can become red and warm. Some men also develop a low fever or urinary symptoms.
Torsion is a surgical emergency. When surgery happens within six hours of symptom onset, the testicle is saved 90% to 100% of the time. After 12 hours, that rate drops to about 50%. By 24 hours, it falls below 10%. If you experience sudden, intense testicular pain, especially with nausea or swelling, go to the emergency room immediately. Waiting to see if it improves on its own risks permanent damage.
Gradual Pain With Swelling: Epididymitis
Epididymitis is an infection or inflammation of the epididymis, the coiled tube that sits behind each testicle and stores sperm. It’s one of the most common reasons for one-sided testicular soreness in adults. The pain typically starts mild and worsens over a day or two. You may notice swelling that begins at the back of the testicle and spreads, along with tenderness in the spermatic cord above it. A small fluid buildup around the testicle is also common.
In sexually active men under 35, the usual culprits are sexually transmitted bacteria like chlamydia or gonorrhea. In older men, the infection more often traces back to urinary tract bacteria, particularly when an enlarged prostate or other obstruction makes the bladder harder to empty. Treatment is a course of antibiotics matched to the likely cause, and symptoms generally start improving within a few days, though full recovery can take a couple of weeks.
Dull Ache That Worsens With Standing
A varicocele is a cluster of enlarged veins inside the scrotum, similar to varicose veins in the legs. It produces a dull, aching discomfort that gets worse as the day goes on or after prolonged standing and tends to ease when you lie down. About 85% of varicoceles occur on the left side. If the veins are large enough, you or a doctor can feel a soft mass above the testicle, sometimes described as feeling like a “bag of worms.” Smaller ones may only be noticeable by touch.
Most varicoceles don’t need treatment. They become a concern mainly when they cause persistent pain that interferes with daily life or when they’re linked to fertility problems, since the extra heat from pooled blood can affect sperm production.
Soreness After a Hit or Injury
Blunt trauma to the groin is an obvious cause of testicular pain, but the severity of the injury isn’t always obvious from the outside. The most common finding after a direct hit is a hematocele, a collection of blood around the testicle. A small one resolves on its own. A large one can compress blood vessels and mimic the reduced blood flow seen in torsion, which makes it harder to assess the full picture without imaging.
A testicular rupture, where the tough outer lining of the testicle breaks, is less common but requires surgical repair. Signs that an injury may be more than a bad bruise include swelling that keeps increasing, pain that doesn’t gradually improve over an hour or two, or visible bruising that spreads across the scrotum. An ultrasound is the standard way to check for serious damage after trauma.
Pain That Starts Somewhere Else
Sometimes the testicle itself is fine, but pain from a nearby structure travels there along shared nerve pathways. Doctors call this referred pain. Two common sources are kidney stones and inguinal hernias. A kidney stone passing through the ureter can send sharp, radiating pain down into the groin and testicle on the same side. An inguinal hernia, where tissue pushes through a weak spot in the abdominal wall near the groin, can press into the scrotum and cause aching or swelling that worsens with lifting or straining.
With referred pain, the testicle usually isn’t tender to the touch and looks normal. The giveaway is often other symptoms: flank pain and blood in the urine with a kidney stone, or a visible bulge in the groin with a hernia.
Small Lumps and Cysts
A spermatocele is a fluid-filled cyst that forms near the top of the testicle in the epididymis. Most are painless and go unnoticed, but a larger one can create a feeling of heaviness, fullness, or mild discomfort on that side. They’re noncancerous and generally don’t need treatment unless they become bothersome.
Testicular cancer, by contrast, typically presents as a painless, hard lump on the testicle itself rather than soreness. Pain is not the usual first sign of cancer, though it can occur in a small percentage of cases. Any new lump or mass in the scrotum is worth getting evaluated, even if it doesn’t hurt, to rule out something serious.
How Doctors Figure Out the Cause
The first step is a physical exam, which gives a doctor a surprising amount of information: where exactly the tenderness is, whether the testicle sits in a normal position, and whether any masses or swelling are present. A color Doppler ultrasound is the go-to imaging test for testicular pain. It shows blood flow patterns in real time, which helps distinguish torsion (reduced flow) from infection (increased flow). For torsion specifically, this type of ultrasound has a sensitivity around 82% and a specificity of 100%, meaning a positive result is highly reliable. Urine tests and swabs can identify the bacteria behind an infection.
Signs You Need Emergency Care
Go to the ER if your testicular pain came on suddenly, is moderate to severe, or is accompanied by nausea, vomiting, or noticeable swelling. These are the criteria emergency departments use to fast-track evaluation, because time matters enormously if torsion is the cause. Pain that builds gradually over days, while still worth a doctor visit, is less likely to be an emergency and can typically be evaluated in an urgent care or primary care setting within a day or two.