Solifenacin is an antimuscarinic medication widely prescribed for overactive bladder syndrome, helping to reduce urinary urgency and frequency. Some men taking solifenacin may wonder whether it could contribute to erectile dysfunction. Whilst erectile dysfunction is not a commonly reported side effect of solifenacin, understanding the potential mechanisms, alternative causes, and management options is important for anyone experiencing sexual difficulties during treatment. This article examines the evidence linking solifenacin to erectile problems, explores why erectile dysfunction may occur in men taking this medication, and provides practical guidance on managing both bladder and sexual health effectively.

What Is Solifenacin and How Does It Work?

Solifenacin is a prescription medication primarily used to treat overactive bladder syndrome (OAB), a condition characterised by urinary urgency, frequency, and sometimes urge incontinence. It belongs to a class of drugs called antimuscarinic agents (also known as anticholinergics), which work by blocking specific receptors in the bladder muscle.

The bladder contains muscarinic receptors, particularly the M3 subtype, which when stimulated cause the detrusor muscle (the main bladder muscle) to contract. In overactive bladder, these contractions occur too frequently or inappropriately, leading to the sudden urge to urinate. Solifenacin is a competitive muscarinic receptor antagonist with relative M3 selectivity. By blocking muscarinic receptors in the bladder wall, it reduces involuntary bladder contractions and increases bladder capacity, allowing patients to hold more urine and reducing the frequency of toilet visits.

Solifenacin is typically prescribed at doses of 5 mg or 10 mg once daily, taken orally as a tablet. The medication is absorbed through the gastrointestinal tract and metabolised primarily in the liver via the cytochrome P450 enzyme system (specifically CYP3A4). Its effects usually become noticeable within a few weeks of starting treatment, and your doctor will typically review your response and tolerability after about four weeks.

Important safety information:

• Contraindications: Solifenacin should not be used if you have urinary retention, severe gastric retention (including paralytic ileus), uncontrolled narrow-angle glaucoma, or myasthenia gravis. It is also contraindicated in severe hepatic impairment.

• Dose adjustments: Lower doses (maximum 5 mg daily) are required in moderate hepatic impairment, severe renal impairment, or when taking strong CYP3A4 inhibitors (such as ketoconazole, clarithromycin, or ritonavir).

• Common side effects include dry mouth, constipation, blurred vision, indigestion, dry eyes, and dizziness or drowsiness. These occur because muscarinic receptors are found throughout the body, not just in the bladder.

• Serious side effects are rare but include urinary retention (inability to pass urine), severe constipation, and very rarely QT prolongation (a heart rhythm abnormality that may cause palpitations or fainting).

Seek urgent medical help if you:

• Cannot pass urine or have severe abdominal pain

• Experience palpitations, fainting, or chest pain

• Develop severe allergic reactions (swelling of face, lips, or throat; difficulty breathing; severe rash)

If you experience any side effects, including those not listed in the patient information leaflet, you can report them via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk or through the Yellow Card app.

References: MHRA/EMC Summary of Product Characteristics (SmPC) for Vesicare (solifenacin); EMA European Public Assessment Report (EPAR) for Vesicare; NHS medicines A–Z: Solifenacin; British National Formulary (BNF) online.

Why Erectile Dysfunction May Occur During Solifenacin Treatment

Erectile dysfunction (ED) is not a commonly reported adverse effect of solifenacin. Where reported in post-marketing surveillance and product information, it appears to be rare or of unknown frequency. There is limited evidence of a direct causal relationship between solifenacin and erectile problems, though the theoretical mechanism warrants consideration.

Muscarinic receptors play a role in various physiological processes, including aspects of sexual function. The parasympathetic nervous system, which uses acetylcholine acting on muscarinic receptors, is involved in achieving and maintaining erections. Theoretically, blocking these receptors could interfere with this process, though this mechanism remains largely theoretical and is not well-established in clinical evidence. Solifenacin's relative selectivity for M3 receptors should minimise such effects, and clinical trial data have not demonstrated a clear pattern of erectile dysfunction as a treatment-emergent adverse effect.

It is crucial to consider alternative explanations for erectile difficulties in patients taking solifenacin:

• Underlying health conditions: Many patients prescribed solifenacin are older adults who may have comorbidities such as diabetes, cardiovascular disease, or neurological conditions—all of which are established risk factors for erectile dysfunction.

• Psychological factors: Overactive bladder itself can cause anxiety, embarrassment, and reduced quality of life, which may indirectly affect sexual confidence and function.

• Other medications: Patients with OAB often take multiple medications for various conditions (antihypertensives, antidepressants, etc.), some of which are known to cause erectile dysfunction. The cumulative anticholinergic burden from multiple medications may also contribute to side effects, particularly in older adults.

• Age-related changes: Natural age-related decline in sexual function may coincide with the period when solifenacin is prescribed.

If erectile dysfunction develops or worsens after starting solifenacin, it is important not to assume causation without proper medical assessment. A thorough evaluation can help identify the true underlying cause and guide appropriate management. Remember that erectile dysfunction can be an early marker of cardiovascular disease and warrants comprehensive assessment.

References: MHRA/EMC SmPC for Vesicare (Section 4.8 Undesirable effects); EMA EPAR for Vesicare (safety section); NICE Clinical Knowledge Summary (CKS): Erectile dysfunction; NHS: Erectile dysfunction.

Managing Sexual Side Effects While Taking Solifenacin

If you experience erectile dysfunction whilst taking solifenacin, there are several practical approaches to consider, always in consultation with your healthcare provider.

Do not stop solifenacin abruptly without medical advice. Overactive bladder symptoms can significantly impact quality of life, and discontinuing effective treatment may worsen urinary problems. Instead, discuss your concerns with your GP or specialist, who can help determine whether solifenacin is genuinely contributing to the problem.

Non-pharmacological measures should be considered first-line for overactive bladder, in line with NICE guidance:

• Bladder training (gradually increasing intervals between toilet visits) can improve bladder capacity and control.

• Pelvic floor muscle exercises (Kegel exercises) can benefit both bladder control and erectile function in some men.

• Fluid and caffeine management: timing fluid intake and limiting caffeine and alcohol can reduce bladder irritation.

• In men with lower urinary tract symptoms, assessment for benign prostatic hyperplasia (BPH) may be appropriate, as alpha-blockers or 5-alpha reductase inhibitors may address both bladder and prostate symptoms.

Medication review and adjustment may be appropriate:

• Your doctor might consider reducing the dose from 10 mg to 5 mg to see if symptoms improve whilst maintaining bladder control.

• Alternative antimuscarinic medications (such as tolterodine, fesoterodine, or oxybutynin) have different receptor selectivity profiles and might be better tolerated.

• Beta-3 agonists like mirabegron work through a completely different mechanism (relaxing bladder muscle via beta-3 receptors rather than blocking muscarinic receptors) and may be considered as an alternative, particularly if antimuscarinic side effects are problematic. Important mirabegron cautions: it can increase blood pressure and is contraindicated in severe uncontrolled hypertension; blood pressure should be monitored before starting and during treatment. Mirabegron is a CYP2D6 inhibitor and may interact with other medications (e.g., metoprolol); it also requires monitoring if used with digoxin.

• Review the total anticholinergic burden from all medications, particularly in older adults, as cumulative effects may include cognitive impairment, confusion, and other side effects.

• If you are taking strong CYP3A4 inhibitors (such as ketoconazole, clarithromycin, or ritonavir), the maximum solifenacin dose is 5 mg daily; your doctor will adjust accordingly.

Lifestyle modifications can support both bladder and sexual health:

• Maintain a healthy weight, as obesity is a risk factor for both overactive bladder and erectile dysfunction.

• Regular physical exercise improves cardiovascular health, which is essential for erectile function.

• Stop smoking and moderate alcohol intake.

Treatment for erectile dysfunction itself may be appropriate if the problem persists. Phosphodiesterase-5 (PDE5) inhibitors such as sildenafil, tadalafil, or vardenafil are effective treatments for ED and can generally be used safely alongside solifenacin. However:

• PDE5 inhibitors are contraindicated if you take nitrates (for angina) or riociguat (for pulmonary hypertension) due to the risk of severe hypotension.

• Use caution if you take alpha-blockers (for high blood pressure or prostate symptoms), as the combination may cause low blood pressure; timing of doses may need adjustment.

• Your GP will assess your cardiovascular status before prescribing PDE5 inhibitors and discuss other options (vacuum devices, intracavernosal injections, or referral to specialist services) if these medications are not suitable.

References: NICE Guideline NG123 (Urinary incontinence and pelvic organ prolapse in women – OAB management principles); NICE Guideline NG97 (Lower urinary tract symptoms in men); MHRA Drug Safety Update on mirabegron and severe hypertension; BNF online: PDE5 inhibitors interactions; BNF online: Mirabegron interactions.

When to Speak to Your GP About Erectile Dysfunction

Erectile dysfunction should not be dismissed as an inevitable consequence of ageing or medication, and it is important to seek medical advice if you experience persistent problems. Your GP can provide a comprehensive assessment and appropriate management.

You should contact your GP if:

• Erectile dysfunction develops or significantly worsens after starting solifenacin or any new medication.

• Sexual difficulties are causing distress, affecting your relationship, or impacting your quality of life.

• You experience erectile dysfunction alongside other symptoms such as reduced libido, fatigue, mood changes, or urinary symptoms beyond those related to overactive bladder.

• You are considering stopping solifenacin due to sexual side effects—your doctor can explore alternatives rather than leaving your overactive bladder untreated.

Seek urgent medical help if you experience:

• Inability to pass urine (acute urinary retention) or severe abdominal pain/constipation whilst taking solifenacin.

• Severe allergic reactions (swelling of face, lips, or throat; difficulty breathing; severe rash).

• Palpitations, fainting, or chest pain, particularly with exertion.

• Priapism (painful erection lasting more than four hours) following treatment for erectile dysfunction—this is a medical emergency.

During your consultation, your GP will likely:

• Take a detailed medical and sexual history to understand the timeline and severity of symptoms.

• Review all current medications, as polypharmacy is a common contributor to erectile dysfunction and anticholinergic burden should be assessed.

• Assess for underlying conditions such as diabetes, hypertension, cardiovascular disease, hormonal imbalances (particularly low testosterone), or psychological factors like depression and anxiety.

• Arrange appropriate investigations in line with NICE Clinical Knowledge Summary guidance, which may include:

– HbA1c or fasting glucose (to screen for diabetes)

– Lipid profile

– Blood pressure measurement

– Morning total testosterone level (if you have symptoms of low libido, reduced energy, or other features suggesting hypogonadism)

– Thyroid function tests (only if clinically indicated)

– Assessment of smoking status and body mass index (BMI)

• Perform cardiovascular risk assessment (e.g., using QRISK3) and discuss lifestyle risk modification, as erectile dysfunction can be an early warning sign of cardiovascular disease. The blood vessels supplying the penis are smaller than coronary arteries and may show dysfunction earlier, providing an opportunity for cardiovascular prevention.

• Discuss treatment options, which might include modifying your current medication regimen, prescribing treatments specifically for ED, or referring you to a specialist if needed:

– Urology or andrology for complex erectile dysfunction, Peyronie's disease, or if initial treatments are ineffective.

– Endocrinology for confirmed hypogonadism or hormonal disorders.

– Cardiology if high cardiovascular risk is identified.

Open communication with your healthcare provider is essential. Many men feel embarrassed discussing sexual problems, but GPs routinely address these issues and can provide evidence-based, confidential support to improve both your bladder symptoms and sexual health.

References: NICE Clinical Knowledge Summary (CKS): Erectile dysfunction – assessment and management; NHS: Erectile dysfunction; NICE CKS: Lower urinary tract symptoms in men; NICE CKS: Overactive bladder (for red-flag symptoms).

Frequently Asked Questions