Is this common?

It’s normal for one of your testicles to be bigger than the other. The right testicle tends to be the bigger one. One of them also usually hangs a little lower than the other within the scrotum.

However, your testicles should never feel painful. And even if one is bigger, it shouldn’t be a completely different shape. See your doctor if you notice that either testicle suddenly hurts or isn’t the same shape as the other.

Read on to learn how to identify healthy testicles, what symptoms to watch out for, and what to do if you notice any abnormal pain or symptoms.

How do I know if one testicle is bigger than the other?

No matter which testicle is bigger, the bigger one will only be larger by a small margin —about half a teaspoon. You shouldn’t feel any pain when you sit, stand, or move around. You also shouldn’t have any redness or swelling, even if one testicle is bigger.

Your testicles are more egg-shaped, rather than round. They’re normally smooth all the way around, with no lumps or protrusions. Neither soft or hard lumps are normal. See your doctor right away if you find any lumps around your testicles.

How to identify healthy testicles

A regular testicular self-exam (TSE) can help you learn what your testicles feel like and identify any lumps, pain, tenderness, and changes in one or both testicles.

Your scrotum should be loose, not retracted or shrunken, when you do a TSE.

Follow these steps:

  1. Use your fingers and thumb to gently roll your testicle around. Don’t roll it around too vigorously.
  2. Along the entire surface of one testicle, check for feelings of lumps, protrusions, changes in size, and tender or painful areas.
  3. Feel along the bottom of your scrotum for your epididymis, a tube attached to your testicle that stores sperm. It should feel like a bunch of tubes.
  4. Repeat for the other testicle.

It’s recommended to do a TSE at least once a month.

What causes one testicle to be bigger?

Possible causes of an enlarged testicle include:

Epididymitis

This is inflammation of the epididymis. It’s usually the result of an infection. This is a common symptom of chlamydia, a sexually transmitted infection (STI). See your doctor if you notice any abnormal pain, burning when you urinate, or discharge from your penis along with inflammation.

Epididymal cyst

This is a growth in the epididymis caused by excess fluid. It’s harmless and doesn’t need any treatment.

Orchitis

Orchitis is testicle inflammation caused by infections, or the virus that causes mumps. See your doctor if you notice any pain, as orchitis can cause damage to your testicles.

Hydrocele

A hydrocele is fluid buildup around your testicle than can cause swelling. This fluid buildup can be normal as you get older, and doesn’t require treatment. However, it can also indicate inflammation.

Varicocele

Varicoceles are enlarged veins within your scrotum. They can cause a low sperm count, but normally don’t need to be treated if you have no other symptoms.

Testicular torsion

Twisting of the spermatic cord can happen when the testicle rotates too much. This can slow or even stop blood flow from your body to the testicle. See your doctor if you feel persistent testicular pain after an injury or pain that goes away and comes back without warning. Testicular torsion is an emergency that requires immediate medical care to save the testicle.

Testicular cancer

Testicular cancer occurs when cancerous cells build up in your testicle. See your doctor right away if you notice any lumps or new growths around your testicles.

When should I see my doctor?

See your doctor if you have any of the following symptoms:

  • pain
  • swelling
  • redness
  • discharge from the penis
  • nausea or vomiting
  • difficulty urinating
  • pain in other parts of your body, such as your back or lower abdomen
  • breast enlargement or tenderness

Your doctor will perform a physical examination of your scrotum and testicles to observe any growths, lumps, or other abnormalities. If your doctor suspects testicular cancer, you’ll also be asked about your medical history to see if your family has a history of testicular cancer.

Other possible tests for diagnosis include:

  • Urine test. Your doctor will take a urine sample to test for infections or conditions of your kidneys.
  • Blood test. Your doctor will take a blood sample to test for tumor markers, which may indicate cancer.
  • Ultrasound. Your doctor will use an ultrasound transducer and gel to view the inside of your testicles on an ultrasound display. This allows them to check blood flow or growths in your testicle, which can identify torsion or cancer.
  • CT scan. Your doctor will use a machine to take several images of your testicles to look for abnormalities.

How is this condition treated?

Oftentimes, treatment isn’t necessary. But if you’re experiencing other symptoms or have a serious underlying condition, your doctor will work with you to develop an appropriate treatment plan.

Here are typical treatment plans for these commonly diagnosed conditions:

Epididymitis

If you have chlamydia, your doctor will prescribe an antibiotic, such as azithromycin (Zithromax) or doxycycline (Oracea). Your doctor may drain pus to relieve swelling and infection.

Orchitis

If orchitis is caused by an STI, your doctor will likely prescribe ceftriaxone (Rocephin) and azithromycin (Zithromax) to fight the infection. You can use ibuprofen (Advil) and a cold pack to relieve pain and swelling.

Testicular torsion

Your doctor may be able to push on the testicle to untwist it. This is called manual detorsion. Surgery is usually necessary to prevent torsion from happening again. The longer you wait after torsion to get treatment, the higher the chance that the testicle will need to be removed.

Testicular cancer

Your doctor may surgically remove your testicle if it contains cancerous cells. Then, the testicle can be tested to determine what type of cancer is present. Blood tests can determine if the cancer has spread beyond the testicle. Long-term radiation therapy and chemotherapy can help destroy cancer cells and prevent them from returning.

Are complications possible?

With timely treatment, most conditions won’t cause any complications.

But if blood flow is cut off to your testicle for too long, the testicle may be removed. In these cases, you may develop a low sperm count or infertility.

Some cancer treatments, such as chemotherapy, may also cause infertility.

What’s the outlook?

There’s no need to worry if you have asymmetrical testicles. But if you notice any new pain, redness, or lumps around your testicles, see your doctor right away for a diagnosis. An infection, torsion, or cancer needs to be treated quickly to prevent complications.

Many causes of an enlarged testicle can be treated with medication or surgery, especially if you get an early diagnosis. If you receive a cancer or infertility diagnosis or have a testicle removed, know that you’re not alone. Many support groups exist for people with cancer and infertility that can help you feel empowered to continue living your life after treatment or surgery.