Why Is One of My Testicles Swollen? Understanding the Causes, Symptoms, and Treatment

Have you noticed that one testicle suddenly feels larger, heavier, or more uncomfortable than usual? It’s understandable to feel concerned. While some men hope the swelling will disappear on its own, a swollen testicle should never be ignored, especially if it’s painful or develops suddenly.

There are many possible testicular pain causes, ranging from minor infections to medical emergencies that require immediate treatment. The good news is that most conditions can be successfully treated when diagnosed early. Understanding the warning signs allows you to seek the right care before complications develop.

In this guide, we’ll explain the most common testicular pain causes, explore different swollen testicle causes, discuss the symptoms to watch for, and outline the available swollen testicle treatment options.

Quick Overview

If you’ve noticed testicle swelling, several conditions could be responsible. Some are relatively harmless, while others require urgent medical attention.

The most common swollen testicle causes include:

• Epididymitis
• Orchitis
• Hydrocele
• Spermatocele
• Varicocele
• Inguinal hernia
• Testicular injury
• Testicular torsion
• Testicular cancer

A swollen testicle may occur alongside pain, redness, warmth, fever, nausea, urinary symptoms, or simply a painless lump. Because these symptoms often overlap, it’s impossible to diagnose the exact cause at home. A prompt assessment by a urologist is the safest approach.

Why Does One Testicle Become Swollen?

A swollen testicle develops when inflammation, infection, injury, fluid build-up, or abnormal tissue causes one testicle to enlarge.

Many men worry because one side suddenly looks different from the other. While it’s perfectly normal for one testicle to naturally sit slightly lower than the other, noticeable enlargement, pain, or a change in shape isn’t considered normal.

The severity of testicle swelling depends on the underlying condition. Some causes develop gradually over several days, while others occur suddenly and require immediate treatment.

Common Testicular Pain Causes

Understanding the underlying condition is the first step towards appropriate treatment. Below are the most common testicular pain causes seen by urologists.

1. Epididymitis

The epididymis is a small, tightly coiled tube located behind each testicle that stores and transports sperm. When this structure becomes inflamed, the condition is called epididymitis.

It is one of the leading swollen testicle causes, particularly in sexually active men and older men with urinary tract infections.

Symptoms often include:

• Gradually increasing pain
• Testicle swelling
• Tenderness behind the testicle
• Redness of the scrotum
• Pain during urination
• Fever or chills

Most cases are caused by bacterial infections, including urinary tract infections or sexually transmitted infections (STIs). Fortunately, antibiotics are usually very effective when treatment begins early. If you experience persistent discomfort alongside swelling, learn more about the diagnosis and treatment of testicular pain.

2. Orchitis

Orchitis refers to inflammation of the testicle itself.

It may occur due to:

• Viral infections such as mumps
• Bacterial infections
• Spread of untreated epididymitis

Typical swollen testicle symptoms include:

• Sudden swelling
• Moderate to severe pain
• Fever
• Fatigue
• Pain during movement

Without timely treatment, severe orchitis may affect fertility, making early diagnosis particularly important. In some cases, untreated infections can contribute to

male infertility

, particularly when both testicles are affected.

3. Testicular Torsion (Medical Emergency)

Among all testicular pain causes, testicular torsion is the condition doctors worry about most.

It occurs when the spermatic cord twists around itself, cutting off the blood supply to the testicle.

Symptoms develop rapidly and usually include:

• Sudden, severe pain
• Rapid swollen testicle
• Nausea and vomiting
• One testicle sitting higher than the other
• Severe tenderness
• Lower abdominal pain

This is a true surgical emergency.

The sooner blood flow is restored, the greater the chance of saving the affected testicle. Ideally, surgery should be performed within six hours of symptoms beginning.

4. Hydrocele

A hydrocele occurs when fluid collects around the testicle.

Although hydroceles are generally harmless, they may become uncomfortable if they grow larger.

Common features include:

• Painless testicle swelling
• Feeling of heaviness
• Smooth enlargement of the scrotum
• Mild discomfort when walking

Some hydroceles disappear naturally, while others require surgical repair if they become large or symptomatic.

5. Spermatocele

A spermatocele is a fluid-filled cyst that develops near the epididymis.

Unlike infections or tumours, spermatoceles are almost always benign and rarely painful.

Symptoms may include:

• A small lump above the testicle
• Mild testicle swelling
• Feeling of fullness
• Occasional discomfort if the cyst enlarges

Many spermatoceles require no treatment. However, larger cysts causing discomfort can be removed surgically if necessary.

6. Varicocele

A varicocele develops when veins inside the scrotum become enlarged, similar to varicose veins in the legs.

It is a common cause of:

• Mild aching pain
• Heaviness
• Visible enlarged veins
• Mild swollen testicle symptoms

Pain often worsens after prolonged standing or exercise and improves when lying down.

Varicoceles may also contribute to reduced fertility in some men and are one of the most common reversible causes of male infertility.

7. Inguinal Hernia

An inguinal hernia occurs when abdominal tissue pushes through a weak area of the abdominal wall into the groin.

Sometimes this tissue extends into the scrotum, causing noticeable testicle swelling.

Signs include:

• Groin bulge
• Swelling extending into the scrotum
• Pain while lifting heavy objects
• Discomfort when coughing

Surgical repair is commonly recommended to prevent complications.

8. Injury or Trauma

A direct blow during sport, exercise, or an accident can result in a swollen testicle.

Depending on the severity, symptoms may include:

• Immediate pain
• Bruising
• Swelling
• Difficulty walking
• Scrotal tenderness

Minor injuries usually improve with rest, ice packs, and pain relief. However, severe trauma may require emergency medical assessment to rule out internal damage.

9. Testicular Cancer

Although less common than infections, testicular cancer remains one of the most important swollen testicle causes to recognise early.

Unlike many other conditions, it often causes little or no pain.

Symptoms include:

• A painless lump
• Gradual enlargement
• Feeling of heaviness
• Firmness of one testicle
• Persistent testicle swelling

testicular cancer has one of the highest cure rates among cancers when diagnosed early, making prompt evaluation essential.

Men who had undescended testicles during childhood have a higher lifetime risk of developing testicular cancer, making regular self-examinations and early medical assessment particularly important.

Swollen Testicle Symptoms to Watch For

Not every condition presents in the same way. Some men experience severe pain, while others notice only subtle swelling.

Common swollen testicle symptoms include:

• One testicle becoming larger than the other
• Pain ranging from mild discomfort to severe agony
• Redness or warmth of the scrotum
• A shiny or stretched appearance of the skin
• Feeling of heaviness
• A hard lump
• Pain during urination
• Burning sensation while passing urine
• Blood in the urine or semen
• Fever and chills
• Nausea or vomiting
• Lower abdominal or groin pain

If these symptoms appear suddenly or continue worsening, medical assessment should not be delayed.

Who Is More Likely to Develop Testicle Swelling?

Although testicle swelling can affect men of any age, certain factors increase the risk.

These include:

• Previous urinary tract infections
• Sexually transmitted infections
• Recent groin injury
• Heavy lifting
• A history of undescended testicles, which may increase the risk of certain testicular conditions later in life
• Previous scrotal surgery
• Family history of testicular cancer
• Poorly controlled infections

Understanding these risk factors can help you recognise potential problems earlier and seek timely medical advice.

When Is a Swollen Testicle an Emergency?

Not every case of testicle swelling requires emergency treatment, but some conditions can permanently damage the testicle if left untreated.

Seek immediate medical attention if you experience:

• Sudden, severe testicular pain
• Rapid swelling of one testicle
• One testicle sitting noticeably higher than the other
• Nausea or vomiting with severe pain
• Fever with increasing swelling and redness
• A significant injury followed by severe pain or persistent swelling

These symptoms may indicate testicular torsion, a condition where the blood supply to the testicle becomes blocked. Prompt surgery—ideally within six hours—offers the best chance of saving the testicle.

Can You Tell What’s Causing the Swelling Yourself?

It’s understandable to search online when you first notice a swollen testicle, but it’s impossible to accurately diagnose the cause at home.

Some conditions share similar symptoms, while others present very differently:

• Infections often cause pain, redness, warmth, and fever.
• A hydrocele usually causes painless swelling that develops gradually.
• A varicocele may feel like a “bag of worms” and cause a dull ache.
• Testicular torsion typically causes sudden, severe pain and rapid swelling.
• Testicular cancer often presents as a painless lump or gradual enlargement.

Although these differences can provide clues, they are not enough to confirm a diagnosis. A physical examination and scrotal ultrasound are usually needed to identify the underlying cause.

How Is a Swollen Testicle Diagnosed?

Diagnosing the cause of testicle swelling begins with a detailed medical history and physical examination.

Your urologist may ask:

• When did the swelling begin?
• Is the pain sudden or gradual?
• Have you had a recent injury?
• Are there any urinary symptoms?
• Have you recently had a fever or infection?

Depending on your symptoms, further investigations may include:

• Scrotal ultrasound with Doppler imaging to assess blood flow and identify abnormalities
• Urine analysis to check for infection
• Blood tests to detect signs of inflammation or infection
• STI screening if a sexually transmitted infection is suspected
• Tumour marker blood tests if testicular cancer is a concern
• CT scan or MRI in selected cases where additional imaging is required

An ultrasound is often the most effective way to distinguish between many swollen testicle causes, allowing treatment to begin promptly.

Swollen Testicle Treatment Options

The most appropriate swollen testicle treatment depends entirely on the underlying diagnosis. Treating the symptoms alone without identifying the cause may delay proper care.

Treatment for Epididymitis and Orchitis

If a bacterial infection is responsible, treatment may include:

• Antibiotics
• Anti-inflammatory medication
• Pain relief
• Rest
• Scrotal support
• Drinking plenty of fluids

Most patients begin to feel better within a few days, although swelling may take longer to fully settle.

Treatment for Hydrocele

Small hydroceles that cause no symptoms may simply be monitored.

If the hydrocele becomes large or uncomfortable, surgery may be recommended to remove the fluid and prevent recurrence.

Treatment for Spermatocele

Most spermatoceles do not require treatment.

However, if the cyst becomes painful or significantly enlarged, surgical removal may be considered.

Treatment for Varicocele

Not every varicocele requires intervention.

Treatment may involve:

• Observation
• Pain relief
• Supportive underwear
• Surgical repair if pain persists or fertility is affected

Treatment for Inguinal Hernia

An inguinal hernia does not usually resolve on its own.

Most patients benefit from surgical repair, particularly if the hernia causes discomfort or continues to enlarge.

Treatment for Testicular Torsion

Testicular torsion requires immediate emergency surgery.

During the procedure, the surgeon untwists the spermatic cord and secures both testicles to reduce the risk of future torsion.

Delaying treatment significantly increases the likelihood of permanent damage or loss of the testicle.

Treatment for Testicular Cancer

If testicular cancer is diagnosed, treatment depends on the stage of the disease.

Options may include:

• Surgical removal of the affected testicle
• Chemotherapy
• Radiotherapy
• Active surveillance following treatment

When diagnosed early, testicular cancer has an excellent long-term outlook.

Can You Prevent Testicle Swelling?

Not every cause of testicle swelling can be prevented, but several healthy habits may reduce your risk.

These include:

• Wearing protective equipment during contact sports
• Seeking prompt treatment for urinary tract infections
• Practising safe sex to reduce the risk of sexually transmitted infections
• Avoiding unnecessary delay if symptoms develop
• Performing monthly testicular self-examinations
• Attending regular health check-ups if you have known risk factors

Knowing what feels normal for your body makes it easier to recognise changes early.

Common Causes of Testicle Swelling

Common Questions About Testicle Swelling

Is one testicle naturally larger than the other?

Yes. It’s normal for one testicle to sit slightly lower or appear marginally larger. However, any sudden increase in size, pain, or new swelling should be assessed by a healthcare professional.

Can a swollen testicle go away on its own?

Sometimes. Mild swelling caused by a minor injury may settle with rest. However, infections, hernias, and many other testicular pain causes require medical treatment, while testicular torsion needs emergency surgery.

Is a swollen testicle always painful?

No. Conditions such as hydrocele, spermatocele, and testicular cancer may cause little or no pain. This is why painless swelling should never be ignored.

Can a sexually transmitted infection cause a swollen testicle?

Yes. Certain sexually transmitted infections can lead to epididymitis or orchitis, resulting in pain, inflammation, and testicle swelling. Early treatment helps prevent complications.

How long does it take for a swollen testicle to heal?

Recovery depends on the underlying cause. Minor injuries may improve within a few days, while infections often take several weeks for swelling to completely resolve. Surgical conditions vary depending on the procedure performed.

If swelling has affected your fertility or you’ve experienced recurrent testicular problems, your urologist may recommend further assessment for male infertility.

Is a swollen testicle always cancer?

No. Most cases of a swollen testicle are caused by infections, fluid build-up, or other non-cancerous conditions. However, because testicular cancer can also present as painless swelling, it’s important to have any new lump or enlargement examined by a urologist.

Early Diagnosis Makes a Difference

A swollen testicle can have many different causes, from minor infections and fluid build-up to conditions that require urgent medical attention. Although some cases are not serious, it’s impossible to determine the cause without a proper medical assessment. Early diagnosis often leads to simpler treatment and better outcomes while helping prevent unnecessary complications.

If you’ve noticed persistent testicle swelling, pain, or any unusual changes, it’s important not to delay seeking medical advice. Dr. Mahesh K Dhanjee, recognised as one of the best urologists in Dubai, is committed to providing compassionate, patient-centred care using the latest diagnostic technologies and advanced treatment techniques. Every patient is listened to, respected, and supported throughout their healthcare journey, whether they’re seeking care for paediatric urology, prostate disease, kidney stones, incontinence, renal oncology, erectile dysfunction, or other urological concerns.

If you’re concerned about a swollen testicle or other urological symptoms, schedule a consultation with Dr. Mahesh K Dhanjee through our website for an accurate diagnosis and personalised treatment plan.