Why Is My Left Testicle Hurting? 9 Causes & When to Act

Left testicle pain is most commonly caused by muscle strain, sitting in one position too long, mild trauma, or a minor infection — but it can also signal testicular torsion, epididymitis, or a hernia, which are medical emergencies requiring same-day care.

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Why Is My Left Testicle Hurting? Understanding Scrotal Pain

Pain in one testicle is common and in most cases benign, but certain causes are time-sensitive. Testicular torsion — a twisted spermatic cord — can cause permanent loss of the testicle within 6 hours of onset if untreated. Knowing the warning signs of serious causes is essential.

The testicles are supplied by a network of nerves and blood vessels that travel down from the abdomen, which is why testicular pain sometimes originates from sources above the scrotum — a kidney stone, an abdominal muscle strain, or a hernia can all refer pain to a testicle. Conversely, inflammation within the testicle itself can radiate upward to the lower abdomen, making the exact source confusing.

Left and right testicles are anatomically distinct. The left testicular vein drains into the left renal vein at a right angle (rather than directly into the vena cava like the right side), which is why varicoceles — enlarged veins in the scrotum — are significantly more common on the left side.

"Testicular torsion is a urologic emergency in which the spermatic cord twists and cuts off blood supply to the testis. Salvage rates are highest (approximately 90–100%) when detorsion occurs within 6 hours of symptom onset and drop significantly after 12–24 hours." — Urology Care Foundation at urologyhealth.org

9 Causes of Left Testicle Pain

Nine causes account for the vast majority of unilateral testicular pain. Read the emergency warning signs section first before working through the full list.

Is This Testicular Torsion? (Emergency)

Testicular torsion occurs when the spermatic cord twists, cutting off blood supply to the testicle. It presents as sudden, severe, unilateral pain — often with nausea, vomiting, and a high-riding or horizontal testicle. It can occur at any age but is most common in adolescents and young adults.

This is a surgical emergency. Go to the emergency room immediately if you have sudden severe testicular pain with nausea or a visibly high-riding testicle. Do not wait to see if the pain resolves on its own.

Is It Epididymitis?

Epididymitis — inflammation of the epididymis (the coiled tube behind the testicle that stores and transports sperm) — is the most common cause of scrotal pain in adult men. It typically comes on gradually over 1–2 days rather than suddenly and is often accompanied by a sensation of warmth, swelling, and sometimes fever. It is most commonly caused by bacterial infection, including sexually transmitted infections such as chlamydia and gonorrhea in younger men, and urinary tract bacteria in older men.

Epididymitis is treated with antibiotics (a 10–14 day course) and is not a surgical emergency, but it does require prompt medical evaluation and prescription treatment.

Could It Be a Varicocele?

A varicocele is an enlargement of the veins within the scrotum, similar to varicose veins in the leg. As noted above, varicoceles are significantly more common on the left side — affecting roughly 15% of all adult men and present in up to 35% of men evaluated for infertility. They typically cause a dull, aching discomfort that worsens after prolonged standing, exercise, or at the end of the day. A varicocele is not a medical emergency and often requires no treatment, though large, symptomatic varicoceles can be surgically corrected.

Is It Orchitis?

Orchitis is inflammation of the testicle itself (as opposed to the epididymis in epididymitis). It is less common and is most often caused by viral infection — notably mumps in men who were not vaccinated, or as an extension of untreated epididymitis. Orchitis causes testicular swelling, warmth, and a heavy aching sensation. Viral orchitis is managed with rest, anti-inflammatories, and supportive care. Bacterial orchitis requires antibiotics.

Could a Hernia Be Referring Pain to the Testicle?

An inguinal hernia — a protrusion of intestinal tissue through a weakness in the abdominal wall near the groin — often causes pain that radiates directly into the testicle on the same side. The pain is usually a dull ache that worsens with standing, straining, coughing, or heavy lifting. A bulge visible in the groin area, especially when straining, is a strong sign of an inguinal hernia. A physical exam by a doctor confirms the diagnosis.

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Is It a Kidney Stone?

Kidney stones can cause pain that radiates from the flank down to the groin and testicle, mimicking primary testicular pain. The pain typically comes in waves, is colicky in nature, and may be accompanied by blood in the urine, nausea, or pain during urination. The testicle itself is not tender on physical examination — a key distinguishing feature from epididymitis or torsion.

Is the Pain From Muscle Strain or Sitting Position?

Prolonged sitting, cycling, or groin muscle strain can cause referred pain to the scrotum and testicle. This type of pain is typically diffuse, mild-to-moderate, and correlates clearly with a specific activity or posture change. It resolves with rest and position change. Cyclists are particularly prone to scrotal nerve compression and referred pain from prolonged saddle pressure.

Is There a Testicular Lump That Needs Investigation?

A painless or mildly tender lump on or within the testicle is always worth medical evaluation — it may represent a cyst (benign), a hydrocele (fluid accumulation), or, in rare cases, testicular cancer. Testicular cancer is the most common cancer in men aged 15–35, but it is highly treatable when caught early. Monthly self-examination allows early detection.

"Testicular cancer is the most common cancer among men between the ages of 15 and 35. When caught early, the 5-year relative survival rate approaches 99%. Men should report any new lumps, changes in size, or unexplained discomfort to their healthcare provider promptly." — American Cancer Society at cancer.org

Can Anxiety or Stress Cause Testicular Pain?

Chronic anxiety and pelvic floor tension can manifest as referred pain in the scrotum or testicles — a condition sometimes called chronic pelvic pain syndrome (CPPS) or testicular pain syndrome. This is a diagnosis of exclusion, meaning all physical causes must be ruled out first. It is more common in men who experience generalized anxiety or sit for long periods in high-stress work environments.

When to Go to the ER Immediately

• Sudden, severe pain in one testicle — possible torsion
• Nausea and vomiting alongside testicular pain — possible torsion
• Visible high-riding or horizontally positioned testicle — torsion sign
• Trauma followed by extreme swelling — possible hematocele

Any of these requires an ER visit, not a next-day GP appointment.

In Short

Left testicle pain is most often benign — from muscle strain, a varicocele, or referred pain from posture — but sudden severe pain with nausea is a medical emergency (possible testicular torsion) requiring an ER visit within hours. Gradual pain with warmth and swelling over 1–2 days points to epididymitis, which needs antibiotics. Any new lump on the testicle should be examined by a doctor regardless of whether it hurts.

What You Also May Want To Know

Why does only my left testicle hurt but not the right?

The left testicle is more susceptible to certain conditions (varicocele, epididymitis) due to anatomical differences in its venous drainage. Left-sided pain is more common for varicoceles specifically. Pain in one testicle rarely mirrors the other unless both have the same infection or systemic condition.

Can blue balls cause testicle pain?

Yes. Prolonged sexual arousal without ejaculation causes temporary congestion in the blood vessels of the scrotum and prostate, leading to a dull aching sensation in the testicles and perineum (sometimes called epididymal hypertension). This is temporary and benign — it resolves within a few hours on its own or following ejaculation.

Is testicle pain related to lower back pain?

Kidney problems — stones, infections, or cysts — commonly refer pain from the flank to the groin and scrotum along the same nerve pathways. If your left testicle pain is accompanied by back or flank pain, nausea, or changes in urination, kidney stone is a strong possibility and warrants evaluation.

What does testicular torsion pain feel like compared to other causes?

Torsion pain is typically sudden, severe, and escalates rapidly — often waking men from sleep. It is usually one-sided and can be accompanied by nausea or vomiting. Epididymitis pain, by contrast, builds over hours to days and is accompanied by warmth and tenderness on the back of the testicle. If you cannot distinguish between the two, treat it as torsion and go to the ER.

Reviewed and Updated on June 5, 2026 by George Wright