Scrotal Swelling: Drugs That Cause or Treat It

What Causes Scrotal Swelling?

Scrotal swelling results from fluid accumulation, inflammation, venous congestion, or a structural mass inside or around the scrotum. The underlying cause determines urgency and treatment. A clinician's first job is to separate the surgical emergencies (testicular torsion, Fournier's gangrene) from the medically manageable conditions (epididymo-orchitis, hydrocele, varicocele) and the drug-induced causes.

Infectious and Inflammatory Causes

Epididymo-orchitis is the single most common inflammatory cause of acute scrotal swelling in men under 35. In sexually active men, Chlamydia trachomatis and Neisseria gonorrhoeae drive most cases. In men over 35 and in men who practice insertive anal intercourse, enteric gram-negative organisms such as Escherichia coli dominate [1].

The CDC 2021 STI Treatment Guidelines state: "For epididymitis most likely caused by chlamydia or gonorrhea, recommended treatment is ceftriaxone 500 mg IM in a single dose plus doxycycline 100 mg orally twice a day for 10 days" [2].

Mumps orchitis still occurs in under-vaccinated populations and accounts for roughly 20-30% of post-pubertal mumps cases, producing unilateral or bilateral testicular swelling that peaks 4-8 days after parotitis onset [3].

Structural Causes

A hydrocele, a fluid collection within the tunica vaginalis, accounts for a large share of non-acute scrotal enlargement. Congenital hydroceles resolve spontaneously in about 80% of infants by age 12 months [4]. In adults, secondary hydroceles form after trauma, infection, or tumor and warrant ultrasound evaluation.

Varicocele, dilation of the pampiniform venous plexus, affects approximately 15% of all men and up to 35% of men evaluated for primary infertility [5]. It rarely causes pain severe enough to seek urgent care but may produce a dull ache and visible scrotal asymmetry. Grade III varicoceles are visible at rest; Grades I and II require palpation or Valsalva maneuver.

Surgical Emergencies

Testicular torsion demands immediate attention. Salvage rates exceed 90% when detorsion occurs within 6 hours but drop below 10% after 24 hours [6]. The condition most commonly affects adolescent males aged 12-18. Absent cremasteric reflex is the single most predictive clinical sign (sensitivity approximately 99%) [7].

Fournier's gangrene, a necrotizing fasciitis of the perineum and scrotum, is rare but carries a mortality rate of 20-40% in published case series. Polymicrobial infection and diabetes are the dominant risk factors [8].

Drugs That Cause Scrotal Swelling

Several drug classes produce scrotal edema as a direct adverse effect. Recognizing drug-induced swelling prevents unnecessary surgical workup and guides medication adjustment.

Calcium-Channel Blockers

Amlodipine and nifedipine are the most frequently implicated agents. Dihydropyridine calcium-channel blockers cause peripheral edema by producing preferential arteriolar dilation, increasing capillary hydrostatic pressure, and driving fluid into the interstitium. The scrotum, with its loose connective tissue, accumulates this fluid conspicuously.

Peripheral edema occurs in 1.8-10.8% of patients taking amlodipine 5-10 mg daily in registration trials [9]. Scrotal edema specifically is underreported in prescribing data but appears in case reports and pharmacovigilance databases. Switching from amlodipine to a non-dihydropyridine agent such as diltiazem or adding a low-dose ACE inhibitor typically resolves the edema within 2-4 weeks [9].

SGLT-2 Inhibitors and Fournier's Risk

The FDA issued a Drug Safety Communication in 2018 warning that SGLT-2 inhibitors, including canagliflozin, dapagliflozin, and empagliflozin, are associated with Fournier's gangrene [10]. Between March 2013 and May 2018, the FDA identified 12 cases in the FAERS database, compared with only 6 cases over more than 30 years for all other antidiabetic drug classes combined [10]. Patients presenting with scrotal pain, erythema, and systemic signs while taking an SGLT-2 inhibitor need emergent evaluation and the drug should be held immediately.

Testosterone Replacement Therapy

TRT produces scrotal swelling through two mechanisms. First, supraphysiologic estradiol conversion, common when testosterone is not properly titrated, causes fluid retention and peripheral edema. Second, exogenous testosterone suppresses luteinizing hormone (LH), leading to testicular atrophy rather than true swelling in most men, but the atrophy can be accompanied by discomfort and altered scrotal contour.

A 2020 review in the Journal of Clinical Endocrinology and Metabolism noted that estradiol-mediated fluid retention is one of the most common patient complaints in TRT clinics, often responding to dose reduction or the addition of anastrozole 0.5-1 mg twice weekly [11]. Anastrozole is an aromatase inhibitor approved for breast cancer (FDA NDA 020541) and used off-label for estrogen management in hypogonadal men on TRT.

Other Implicated Agents

Several additional drug classes produce scrotal or genital edema through systemic fluid retention or direct local effects:

• Minoxidil (oral): a potent vasodilator used in resistant hypertension; causes significant fluid retention and scrotal edema in some patients.
• Lithium: chronic lithium use has been linked to non-inflammatory scrotal edema through renal tubular effects on sodium retention.
• NSAIDs in high doses: prostaglandin inhibition reduces renal filtration, producing fluid retention that can manifest as dependent scrotal edema.
• Certain chemotherapy agents: docetaxel and paclitaxel cause capillary leak syndrome; scrotal edema occurs in up to 64% of patients on cumulative docetaxel doses above 400 mg/m², according to a review in the Annals of Oncology [12].

The table below summarizes the mechanism and management strategy for each drug class:

| Drug Class | Mechanism of Scrotal Swelling | Management | |---|---|---| | Dihydropyridine CCBs (amlodipine, nifedipine) | Arteriolar dilation, capillary hydrostatic pressure | Switch to diltiazem or add ACE inhibitor | | SGLT-2 inhibitors | Fournier's gangrene risk | Hold drug, emergent surgical evaluation | | Testosterone (TRT) | Estradiol elevation, fluid retention | Dose reduction, anastrozole | | Minoxidil (oral) | Systemic fluid retention | Diuretic co-therapy, dose review | | Docetaxel / paclitaxel | Capillary leak syndrome | Dexamethasone premedication, dose assessment | | NSAIDs (chronic, high-dose) | Prostaglandin inhibition, sodium retention | Dose reduction, renal function review |

How Scrotal Swelling Is Diagnosed

Diagnosis begins at the bedside, not with imaging. A focused history covering onset speed, trauma, sexual activity, fever, and current medications narrows the differential before any test is ordered.

Physical Examination

Three examination findings drive triage:

1. The cremasteric reflex. Its absence strongly suggests testicular torsion [7].
2. Transillumination. A hydrocele transmits light; a solid mass or hematocele does not.
3. Position of the testis. A high-riding testis with a horizontal lie indicates torsion until proven otherwise.

Prehn's sign (pain relief with testicular elevation) was historically taught to differentiate epididymo-orchitis from torsion, but its sensitivity and specificity are insufficient to guide clinical decisions. The 2019 American Urological Association guidelines do not recommend relying on Prehn's sign alone [13].

Scrotal Ultrasound with Doppler

Doppler ultrasound is the imaging standard. In testicular torsion, absent or markedly reduced intratesticular blood flow has a reported sensitivity of 89-100% and specificity of 97-100% [6]. In epididymo-orchitis, ultrasound shows hyperemia of the epididymis and, when orchitis is present, increased testicular blood flow.

Ultrasound is also the primary tool for characterizing hydroceles, varicoceles, and intratesticular masses. A 2021 systematic review in BJU International confirmed that scrotal ultrasound alters clinical management in up to 40% of men presenting with scrotal symptoms when the physical examination is equivocal [14].

Laboratory Tests

In suspected infectious epididymo-orchitis, the CDC recommends first-void urine for nucleic acid amplification testing (NAAT) for C. Trachomatis and N. Gonorrhoeae, plus urinalysis and urine culture. Urethral swab NAAT is an alternative [2]. Serum tumor markers, specifically alpha-fetoprotein (AFP), beta-human chorionic gonadotropin (b-hCG), and lactate dehydrogenase (LDH), are drawn if ultrasound identifies an intratesticular mass suspicious for germ cell tumor.

When to Worry: Red Flags That Need Same-Day Evaluation

Not every scrotal swelling demands an emergency room visit. These signs do:

• Sudden-onset severe unilateral pain (torsion until proven otherwise)
• Fever above 38.5°C combined with scrotal erythema and systemic toxicity (Fournier's gangrene)
• Rapid spread of erythema to perineum or inner thighs
• Absence of cremasteric reflex
• Scrotal swelling in a child under 16 with acute pain

The 6-hour window for testicular torsion is firm. A 2010 retrospective study of 670 torsion patients published in the Journal of Urology found that orchidectomy rates were 9.7% when surgery occurred within 6 hours versus 69.9% when surgery was delayed beyond 24 hours [15].

Treatments for Scrotal Swelling: A Drug-by-Drug Breakdown

Treatment follows the underlying cause directly. There is no single "anti-swelling" regimen.

Antibiotics for Epididymo-Orchitis

The CDC 2021 STI Treatment Guidelines provide two first-line regimens based on likely causative organism [2]:

Sexually transmitted etiology (age <35, typical sexual history):

• Ceftriaxone 500 mg IM single dose PLUS doxycycline 100 mg orally twice daily for 10 days

Enteric organism etiology (age >35 or insertive anal intercourse):

• Levofloxacin 500 mg orally once daily for 10 days
• Alternative: ofloxacin 300 mg orally twice daily for 10 days

Doxycycline reaches tissue concentrations in the epididymis sufficient to cover C. Trachomatis within 48 hours of starting therapy. Clinical improvement in pain and swelling typically begins within 3 days; full resolution of induration may take 4-6 weeks [2].

Anti-Inflammatory Drugs

NSAIDs reduce pain and scrotal inflammation in epididymo-orchitis. Ibuprofen 400-600 mg every 6-8 hours with food is the standard choice for mild-to-moderate pain. Scrotal elevation with a supportive garment reduces edema through gravity drainage and is recommended in all acute inflammatory scrotal conditions [13].

Surgical and Procedural Treatments

Testicular torsion requires manual detorsion followed by bilateral orchidopexy within the same operative session. Manual detorsion succeeds in approximately 30-70% of attempts but surgical fixation remains mandatory even after successful manual reduction to prevent recurrence [15].

Hydrocelectomy is indicated for symptomatic adult hydroceles not resolving with observation. Aspiration alone carries a recurrence rate above 70% within 12 months; aspiration combined with sclerosant injection (e.g., tetracycline or sodium tetradecyl sulfate) reduces recurrence to roughly 35-50% but causes significant post-procedure discomfort [4].

Varicocele repair via microsurgical subinguinal ligation is the standard approach for varicoceles causing pain or associated with infertility. A 2012 Cochrane review (Intervention review, CD000479) found that varicocelectomy improved spontaneous pregnancy rates compared with observation (OR 2.23, 95% CI 1.32-3.78) in men with clinical varicocele and abnormal semen parameters [16].

Managing Drug-Induced Scrotal Edema

For calcium-channel blocker-induced edema, three options exist: dose reduction, class switch to a non-dihydropyridine, or addition of an ACE inhibitor. A head-to-head trial published in Hypertension (2011, N=573) found that adding ramipril 5 mg to amlodipine 10 mg reduced peripheral edema rates from 27.6% to 10.3% at 12 weeks [17].

For TRT-associated swelling driven by estradiol elevation, target serum estradiol levels of 20-40 pg/mL. Values consistently above 50 pg/mL correlate with fluid retention symptoms in most clinical TRT protocols. Anastrozole 0.5 mg twice weekly is the most commonly used aromatase inhibitor in this context, though prescribers should recheck estradiol at 6-8 weeks to avoid over-suppression, which carries its own risks including reduced libido and bone density loss [11].

Scrotal Swelling in the Context of Hormone Therapy

Men receiving hormone therapy for hypogonadism or gender-affirming care form a distinct patient group with specific scrotal swelling risk profiles.

Hypogonadal Men on TRT

Hypogonadism affects an estimated 2-6% of men, with prevalence rising to 30-40% in men with type 2 diabetes and obesity [18]. When these men start TRT, several medication-related scrotal changes can occur:

• Estradiol-mediated edema (described above)
• Testicular volume reduction due to LH suppression, often 20-30% over the first 6-12 months
• Rarely, epididymal congestion presenting as mild posterior scrotal discomfort and fullness

Human chorionic gonadotropin (hCG) co-therapy at 500-1,000 IU subcutaneously every 3-5 days maintains intratesticular testosterone and preserves testicular volume in men who wish to avoid atrophy. A 2005 randomized trial in Journal of Clinical Endocrinology and Metabolism (N=29) showed that hCG co-administration with testosterone enanthate maintained testicular volume within 4% of baseline versus a 25% volume reduction in the testosterone-only group [19].

Gender-Affirming Hormone Therapy

Transgender women receiving estrogen therapy may notice labial or scrotal tissue changes as part of expected feminization. Swelling distinct from expected feminization, particularly unilateral swelling with pain, warrants the same urgent evaluation applied to cisgender men.

Scrotal Swelling and Cancer: What to Rule Out

Testicular cancer accounts for roughly 9,470 new cases annually in the United States, according to the National Cancer Institute's SEER data [20]. It is the most common solid tumor in men aged 15-35. Most cases present with painless unilateral testicular enlargement, though up to 30% present with dull ache or heaviness.

Any discrete intratesticular mass on ultrasound is germ cell tumor until proven otherwise. Testicular cancer is exquisitely chemosensitive; even metastatic disease achieves 5-year survival rates above 95% with BEP chemotherapy (bleomycin, etoposide, cisplatin) [20]. The critical step is not delaying biopsy or radical orchiectomy for a suspicious mass.

Scrotal skin thickening combined with inguinal lymphadenopathy may signal lymphoma or scrotal skin cancer and requires dermatology and urology co-evaluation.

A Practical Decision Framework for Clinicians

The following sequence applies to any male patient presenting with new scrotal swelling:

1. Assess for torsion first. Acute pain onset, absent cremasteric reflex, and high-riding testis call for emergent urology referral or operating room, not imaging.
2. Check the medication list. Amlodipine, SGLT-2 inhibitors, TRT, and docetaxel each have specific scrotal swelling mechanisms.
3. Order Doppler ultrasound for all non-emergent presentations to characterize the anatomy.
4. Test for STIs in sexually active men under 35 with epididymal tenderness.
5. Check tumor markers if ultrasound reveals an intratesticular lesion.
6. Review hormone levels (testosterone, estradiol, LH, FSH) if the patient is on TRT or other hormonal therapy.
7. Follow the CDC 2021 STI Treatment Guidelines antibiotic protocol for confirmed or suspected epididymo-orchitis.