testicular on one side
Informed by recognized medical guidance
Overview
A lump, swelling, pain, or other change in one testicle is a common reason men see a doctor. Most of the time it is not cancer, but it is always worth checking. The testicles are the two oval-shaped organs inside the scrotum that make sperm and the hormone testosterone.
Key facts
- Most lumps and swellings in the testicle are not cancer, but any new lump should be checked by a doctor.
- Sudden severe pain in one testicle can be an emergency, especially if it comes on quickly.
- Testicular cancer is rare but most common in younger and middle-aged men, and is highly treatable when found early.
- A simple ultrasound scan is often all that is needed to diagnose the cause.
Yes. Many men experience a lump, swelling, or discomfort in one testicle at some point. Most causes are not serious, but they all deserve a proper check-up.
Men and boys of all ages can be affected. Testicular torsion (twisting of the tube that carries blood to the testicle) is most common in teenagers and young men. Testicular cancer is most often seen in men aged 15 to 45. Other causes, such as cysts or infections, can happen at any age.
Symptoms
- Sudden, severe pain in one testicle, especially if it came on within minutes or hours
- Pain along with nausea, vomiting, or a racing heartbeat
- Swelling of the scrotum that appears very quickly
- The testicle has become hard, red, and extremely tender
- ⚠A new lump or firm area in a testicle
- ⚠Any change in the size or shape of a testicle
- ⚠Blood in the urine or semen
- ⚠A recent injury to the testicle that causes increasing pain or swelling
Common symptoms
- A hard lump or smooth swelling in one testicle
- Dull ache or heavy feeling in the scrotum
- Pain in one testicle that may come and go
- Change in the size or shape of one testicle
- Redness or warmth in the scrotum
- Fluid or a soft, squishy swelling around the testicle
Symptoms in children
- A swelling or lump in the scrotum
- Crying or fussiness in a baby that cannot be explained
- A boy older than 1 saying it hurts to walk or sit
- Nausea or vomiting along with scrotal pain
- One testicle feeling higher or tilted
Symptoms in older adults
- A dull ache or heaviness in the scrotum
- Swelling that gets worse when standing for a long time
- Pain or burning when passing urine (more likely with infection)
- A lump that feels smooth and separate from the testicle
Causes
Main causes
- Testicular torsion: the tube carrying blood to the testicle twists, cutting off blood supply. This is a surgical emergency.
- Epididymitis: inflammation or infection of the coiled tube at the back of the testicle, often caused by a urine infection or sexually transmitted infection.
- Hydrocele: a fluid-filled sac around the testicle that causes painless swelling.
- Varicocele: enlarged veins in the scrotum, similar to varicose veins, which can cause a dull ache.
- Spermatocele: a fluid-filled cyst in the epididymis, usually painless and benign.
- Inguinal hernia: part of the bowel pushing through the groin into the scrotum.
- Testicular cancer: an abnormal growth in the testicle that appears as a hard lump.
- Injury: trauma to the scrotum can cause bruising, swelling, and pain.
Risk factors
- Age under 25 for testicular torsion
- Age 15 to 45 for testicular cancer
- An undescended testicle at birth (not fully in the scrotum)
- Family history of testicular cancer
- Previous testicular cancer in one testicle
- Strenuous physical activity or injury to the groin
When to see a doctor
See a doctor urgently if:
- Sudden severe pain in one testicle, especially if it started quickly and does not go away
- A lump that feels hard or new, even if it does not hurt
- Swelling that gets rapidly worse
- Pain with fever, vomiting, or feeling very unwell
Book a routine appointment if:
- A dull ache that lasts more than a few days
- Any change in the way a testicle feels or sits
- A swelling that comes and goes with standing or lying down
Diagnosis
The doctor will start by asking about your symptoms and examining your scrotum. They may shine a light through it (transillumination) to check for fluid. The most reliable test is an ultrasound, which creates a picture of the testicle and nearby structures.
Tests that may be done
- Physical examination of the scrotum and testicles
- Ultrasound scan of the scrotum (painless, uses sound waves)
- Urine test to check for infection
- Blood tests to check for infection or markers that can suggest cancer
What to expect at your appointment
The examination usually takes a few minutes. You will be asked to lower your underwear, and the doctor will gently feel the scrotum, testicles, and abdomen. An ultrasound involves lying down while a gel is applied and a small device is moved over the area. It is painless and quick. If the doctor suspects cancer, they may refer you to a specialist for further tests, including imaging and sometimes a biopsy.
Treatment
Treatment depends entirely on the cause. If it is an infection, antibiotics may be prescribed. If it is testicular torsion, emergency surgery is needed to save the testicle. If it is a cyst or fluid collection, it may not need any treatment at all. If cancer is found, a team of specialists will create a personal treatment plan.
Self-care at home
- Wear supportive underwear (briefs or athletic support) to reduce movement and pressure.
- Lie down and rest if you have a dull ache or heaviness.
- Apply a cold compress on the outside of the scrotum for short periods to reduce swelling (never apply ice directly to the skin).
- Take over-the-counter pain relief only if a doctor or pharmacist says it is safe for you, and follow the recommended dose.
- Avoid strenuous activity or heavy lifting until the cause is known.
Medical treatments
If the cause is a bacterial infection, a doctor will usually prescribe a course of antibiotics. If a sexually transmitted infection is suspected, your partner may also need treatment. Pain relievers and anti-inflammatory medicines may be recommended, but only under medical advice. If testicular torsion is diagnosed, surgery is urgent and must happen within hours to try to save the testicle. For fluid collections (hydrocele) or varicoceles, surgery or a minor procedure may occasionally be offered if symptoms are bothersome.
When is surgery considered?
Surgery is an emergency for testicular torsion: the surgeon untwists the cord and fixes the testicle in place to prevent it happening again. Surgery is also used to remove a testicle when cancer is present (radical inguinal orchidectomy). Removing one testicle does not usually affect erections, sex drive, or fertility, because the other testicle can produce enough sperm and testosterone. You may also be offered a prosthetic testicle to restore a natural appearance.
Living with this condition
If you have had treatment for a testicle problem, give yourself time to heal. Follow your doctor’s advice about activity, lifting, and returning to work or sport. It is normal to feel anxious or worried, but talking to a trusted person or a counsellor can help. After surgery, you may need to avoid sex and heavy exercise for a few weeks.
Lifestyle tips
- Do a monthly self-exam in the shower when the scrotum is relaxed.
- Wear a protective cup during contact sports or activities that could injure the groin.
- Do not ignore changes—early action gives the best results.
- Keep follow-up appointments if you have had treatment for cancer or torsion.
Diet and exercise
Eating a balanced diet with plenty of fruits, vegetables, and whole grains supports overall health and recovery. Gentle exercise like walking is fine after most treatments, but ask your doctor when you can resume vigorous activity or heavy lifting. Staying active helps maintain a healthy weight, which reduces the risk of many cancers.
Mental health and emotional wellbeing
It is completely natural to feel worried, embarrassed, or anxious about a lump or pain in the testicle. Many men delay seeing a doctor because they are scared or embarrassed. Remember that healthcare professionals are used to these symptoms and will treat you with respect. If you feel low, anxious, or avoid thinking about it, speak to your doctor or a mental health professional.
Prevention
Most testicular conditions cannot be prevented, but finding problems early can prevent serious harm. Testicular torsion is an emergency—knowing the signs and acting fast can save the testicle. Testicular cancer has no known prevention, but self-awareness improves early detection. Avoiding injury to the groin with protective gear is also sensible.
Screening programmes
There is no routine screening programme for testicular cancer for the general public. Instead, doctors recommend that all men become familiar with the normal size, shape, and feel of their testicles. If you notice any change, see a doctor promptly. This is especially important for men with risk factors such as an undescended testicle or a family history.
Complications
If left untreated
- Testicular torsion can lead to the death of the testicle if surgery is delayed more than a few hours. It may then need to be removed.
- An untreated infection can spread to the bloodstream or cause an abscess (a pocket of pus).
- Testicular cancer can spread to other parts of the body, especially the lymph nodes, lungs, and liver, if not treated early.
- A hydrocele or large varicocele can cause ongoing discomfort, reduced fertility, or a trapped hernia.
Long-term outlook
The outlook is very good for almost all testicular problems. Even testicular cancer is highly treatable, especially when caught early. Most treatment options do not prevent a man from having a normal sex life or children. After treatment, ongoing check-ups help catch any issues early. You will not be alone—doctors and nurses will guide you at every step.
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Always verify with your doctor
Health guidelines vary by country and region. The information in this article is based on international clinical guidelines but may not reflect the specific guidelines, medications, or practices in your country. Always discuss your health concerns with your own doctor or healthcare provider, and refer to your local national health guidelines where available.
Important notice This information is for educational purposes only. It does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your specific situation. If you are experiencing a medical emergency, call your local emergency services immediately.
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Sources and guidance
This article is educational and is prepared with reference to recognized health information and clinical guidance sources where available. Specific source links may vary by topic.
Last updated: July 31, 2026
Educational note: This information is for education only and is not a diagnosis.
Use it to support, not replace, advice from a licensed clinician.
If symptoms are severe, worsening, or urgent, call your local emergency number or seek emergency care.