You may think that when a health problem affects your testicles, pain symptoms will be felt on both the right and left sides. But plenty of conditions can trigger symptoms only on one side.

This is because the anatomy of your left testicle is slightly different from that of your right.

Your left testicle in particular is more vulnerable to a number of conditions, such as varicoceles, caused by vein problems, and testicular torsion, which is a twisting of the testicle inside the scrotum.

If your left testicle hurts, it’s important to know some of the more common causes, their symptoms, and some treatment options that your doctor may discuss with you.

You have arteries throughout your body that deliver oxygen-rich blood from the heart to bones, tissue, and organs.

You also have veins that carry oxygen-depleted blood back to the heart and lungs. When a vein in a testicle becomes enlarged, it’s called a varicocele. Varicoceles affect up to 15 percent of males.

Like varicose veins in your legs, varicoceles may appear bulgy under the skin of your scrotum.

They tend to form in the left testicle because the vein on the left side hangs lower. This makes it a little more difficult for the valves in that vein to keep pushing blood up into the body.

Treatment

You may not need treatment for a varicocele, though if it’s causing you pain or fertility problems, then you should discuss treatment options with a urologist.

Surgery can close off blood flow in the enlarged part of the affected vein and reroute it through other veins. Surgery is usually successful in eliminating pain and allowing for healthy testicle function. Fewer than 1 in 10 surgical patients have recurring varicoceles.

Orchitis is inflammation of the testicles, usually triggered by a virus or bacterial infection. Pain may start in the left or right testicle and remain there or spread throughout the scrotum.

In addition to pain, the scrotum may swell and turn warm. The skin may turn reddish, and the scrotum may feel firmer or more tender than usual.

The mumps virus is often the cause of orchitis. If that is the case, then symptoms in the scrotum may not appear for up to a week. Sexually transmitted infections (STIs), such as gonorrhea, or a urinary tract infection may also lead to orchitis.

Treatment

Treatment options for orchitis depend on its underlying cause. A bacterial infection can be treated with antibiotics. A virus, such as the mumps, usually just needs time to resolve itself. Over-the-counter pain medications may help ease your symptoms.

A spermatocele is a cyst or fluid-filled sac that forms in the tube that carries sperm from the upper part of a testicle. A spermatocele can develop in either testicle.

If the cyst remains small, you may never have any symptoms. If it grows, that testicle may hurt and feel heavy.

You may notice a change in the affected testicle during a self-exam. If you do, you should see your doctor. It’s unknown why spermatoceles form. If you have no symptoms, you may not need any treatment.

Treatment

If you’re experiencing pain and discomfort, a surgical procedure called a spermatocelectomy can remove the cyst.

The operation does carry the risk of affecting fertility, so in some cases, men are advised to wait until they are done having children before undergoing the procedure.

Considered a medical emergency, testicular torsion occurs when the spermatic cord becomes twisted in the testicle, cutting off its blood supply. The spermatic cord is a tube that helps support the testicles in the scrotum.

If the condition isn’t treated within six hours, a man could lose the affected testicle. Testicular torsion is somewhat unusual, affecting about 1 in 4,000 young men.

One of the most common causes of testicular torsion is a condition called “bell clapper” deformity. Instead of having a spermatic cord that holds the testicles firmly in place, someone born with bell clapper deformity has a cord that allows the testicles to move more freely. This means the cord can be more easily twisted.

Testicular torsion usually affects only one testicle, with the left testicle being the most common. The pain usually comes on suddenly and with swelling.

Treatment

Testicular torsion must be treated surgically, though an emergency room doctor may be able to temporarily untwist the cord by hand. An operation involves securing the testicle with sutures to the inner wall of the scrotum to avoid future twisting.

If bell clapper deformity is diagnosed, the surgeon may secure the other testicle to the scrotum even if there’s been no torsion.

Inside the scrotum, a thin layer of tissue surrounds each testicle. When fluid or blood fills this sheath, the condition is called a hydrocele. Usually the scrotum will swell, and there may or may not be pain. A hydrocele can develop around one or both testicles.

A hydrocele is more common in infants and tends to resolve itself within a year or so after birth. But inflammation or injury can cause a hydrocele to form in older boys and men.

Treatment

Surgery may be needed to remove the hydrocele. You may need to have fluid or blood drained from around the testicle after the operation, which is called a hydrocelectomy.

Follow-up appointments and self-exams are recommended, as a hydrocele can form again, even after one is removed.

The testicles are vulnerable to injuries in sports, fights, or accidents of various types. Because the left testicle tends to hang lower than the right one, the left side is slightly more vulnerable to injury.

While mild trauma to the testicles may lead to temporary pain that eases with time and ice, more serious injuries should be evaluated by a doctor. The possible formation of a hydrocele or the rupture of a testicle requires urgent medical attention.

Treatment

In cases of serious damage to the testicle, surgery may be needed to save the testicle or prevent complications. Milder injuries may be treated with oral painkillers for a day or two.

When cancer cells form in the testicles, it’s called testicular cancer. Even if cancer spreads to another part of your body, the diagnosis is testicular cancer. It’s not always clear why a man develops this type of cancer.

Risk factors include a family history of testicular cancer and having an undescended testicle. But someone with no risk factors may develop the disease.

Testicular cancer is usually first noticed during a self-exam or a physical exam by a doctor. A lump or swelling in the scrotum can indicate a cancerous tumor.

At first, there may be no pain. But if you notice a lump or other change in one or both testicles, and you’re experiencing even mild pain there, see a doctor soon.

Treatment

Treatment for testicular cancer depends on the type of cancer and how much the tumor has grown or the cancer has spread. Some options include:

  • Radiation therapy. This involves using high-energy beams to destroy cancer cells. It’s usually done if the cancer has spread to nearby lymph nodes.
  • Chemotherapy. You will either take oral medications or have them injected into the body to seek out cancer cells to destroy. It tends to be used if the cancer has spread beyond the testicles.
  • Surgery. This will remove the tumor, and often involves removing the testicle, though normal sexual activity and fertility are typically unaffected.

Testicular pain of any kind on one or both sides can be distressing. Most cases don’t require urgent medical attention, though persistent pain should be evaluated by a doctor — a urologist, if possible.

If testicle pain comes on suddenly and severely, or develops along with other symptoms, such as fever or blood in your urine, then see a doctor immediately. If the pain is mild, but doesn’t subside after a few days, then make an appointment.

Likewise, if you feel a lump or other change in your testicles, see a urologist or at least make an appointment soon with your primary care doctor.