Many men taking sildenafil for erectile dysfunction or pulmonary hypertension may wonder whether this medication could trigger gout, particularly if they develop joint pain whilst on treatment. Gout is a painful form of inflammatory arthritis caused by elevated uric acid levels, and certain medications are known to increase gout risk. This article examines the evidence regarding sildenafil and gout, exploring whether there is a genuine causal link or whether the association reflects shared risk factors. Understanding this relationship helps patients and healthcare professionals make informed decisions about treatment safety and management.

What Is Sildenafil and How Does It Work?

Sildenafil is a medication primarily used to treat erectile dysfunction (ED) and pulmonary arterial hypertension. In the UK, it is available under various brand names, including Viagra for erectile dysfunction and Revatio for pulmonary hypertension. While most sildenafil products require a prescription, Viagra Connect (50mg) is available as a Pharmacy (P) medicine without prescription following consultation with a pharmacist.

Sildenafil belongs to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors. It works by blocking the enzyme phosphodiesterase type 5, which is found in the smooth muscle cells lining blood vessels. When sexual stimulation occurs, the body releases nitric oxide, which triggers a cascade of chemical reactions leading to increased levels of cyclic guanosine monophosphate (cGMP). This compound causes blood vessels to relax and dilate, particularly in the penis, facilitating increased blood flow and enabling an erection. By inhibiting PDE5, sildenafil prevents the breakdown of cGMP, thereby prolonging its effects.

For erectile dysfunction, sildenafil is typically taken approximately 30-60 minutes before sexual activity, with effects lasting 4-6 hours. It should not be taken more than once daily. The standard starting dose is 50mg, which may be adjusted based on efficacy and tolerability. For pulmonary arterial hypertension, the medication is usually taken as 20mg three times daily to help reduce blood pressure in the lungs and improve exercise capacity.

Common side effects of sildenafil include:

• Headaches

• Facial flushing

• Indigestion or dyspepsia

• Nasal congestion

• Visual disturbances (such as a blue tinge to vision)

• Dizziness

Sildenafil should not be taken with nitrate medications (used for angina) or guanylate cyclase stimulators like riociguat due to the risk of severe hypotension. Caution is needed when taking sildenafil with alpha-blockers, strong CYP3A4 inhibitors (such as ritonavir, ketoconazole, or erythromycin), and grapefruit juice, which can increase sildenafil levels.

Seek immediate medical attention if you experience:

• An erection lasting longer than 4 hours (priapism)

• Sudden vision or hearing loss

• Severe chest pain

The MHRA advises that patients should always obtain sildenafil through legitimate healthcare channels to ensure product safety and authenticity. Any suspected side effects can be reported through the MHRA Yellow Card scheme.

Understanding Gout: Causes and Risk Factors

Gout is a common and painful form of inflammatory arthritis caused by the accumulation of uric acid crystals in joints and surrounding tissues. It occurs when uric acid levels in the blood become elevated (a condition called hyperuricaemia, typically defined as serum urate above 360 micromol/L), leading to crystal formation that triggers intense inflammation. The condition typically affects the big toe initially, though it can involve other joints including the ankles, knees, fingers, and wrists.

Uric acid is a natural waste product formed when the body breaks down purines—substances found in certain foods and produced naturally by the body. Normally, uric acid dissolves in the blood, passes through the kidneys, and is excreted in urine. However, when the body produces too much uric acid or the kidneys cannot eliminate it efficiently, levels rise and crystals may form in joints.

Key risk factors for developing gout include:

• Dietary factors: High consumption of purine-rich foods (red meat, seafood, organ meats) and excessive alcohol intake, particularly beer

• Obesity: Excess body weight increases uric acid production and reduces kidney excretion

• Medical conditions: Hypertension, diabetes, metabolic syndrome, chronic kidney disease, and cardiovascular disease

• Medications: Diuretics (water tablets), low-dose aspirin, and certain immunosuppressants (such as ciclosporin and tacrolimus)

• Gender and age: Men are more commonly affected, particularly after age 40; women's risk increases after menopause

• Family history: Genetic predisposition plays a significant role

• Dehydration: Insufficient fluid intake can concentrate uric acid levels

According to NICE guidance (NG219), gout affects approximately 2.5% of the UK population, with prevalence increasing with age. The condition presents as acute attacks characterised by sudden onset of severe joint pain, swelling, redness, and warmth, typically reaching maximum intensity within 6-24 hours. Untreated flares commonly resolve within 5-14 days. Between attacks, patients may be completely symptom-free, though without proper management, attacks can become more frequent and involve multiple joints.

When to Seek Medical Advice About Gout Symptoms

Recognising when to seek medical attention for suspected gout is crucial for proper diagnosis, effective treatment, and prevention of complications. If you experience sudden, severe joint pain—particularly in the big toe—accompanied by swelling, redness, and extreme tenderness, you should contact your GP practice for assessment, ideally within 24-48 hours of symptom onset.

You should seek urgent medical advice if:

• The affected joint becomes extremely painful and you cannot bear weight or use the limb

• You develop a high fever (above 38°C) alongside joint symptoms, which could indicate septic arthritis—a medical emergency requiring same-day hospital assessment

• The skin over the joint appears infected (increasingly red, hot, or with discharge)

• You experience severe symptoms and have not been previously diagnosed with gout

If urgent care is needed, contact NHS 111, attend an urgent treatment centre or A&E as appropriate.

For first-time presentations, your GP will typically arrange investigations to confirm the diagnosis. According to NICE guidelines (NG219), the gold standard diagnostic test is synovial fluid analysis obtained through joint aspiration, which can identify uric acid crystals under polarised light microscopy. When aspiration is not feasible, musculoskeletal ultrasound or dual-energy CT (DECT) may be used. Blood tests measuring serum uric acid levels should be performed, though these can be misleadingly normal during an acute attack and should be rechecked at least 2 weeks after a flare resolves. X-rays are generally not helpful in early gout but may show characteristic changes in chronic disease.

Acute gout is typically treated with NSAIDs, colchicine, or corticosteroids, with the choice depending on individual factors including kidney function.

Contact your GP for routine review if:

• You experience recurrent gout attacks (two or more per year)

• You have been diagnosed with gout but your current treatment is not preventing attacks

• You develop visible tophi (chalky deposits under the skin)

• You have concerns about medication side effects

• You need advice on lifestyle modifications to reduce attack frequency

Early medical intervention allows for appropriate acute management and consideration of long-term urate-lowering therapy to prevent future attacks and joint damage. The treatment target is to maintain serum urate below 360 micromol/L, or below 300 micromol/L in severe or tophaceous disease. Your GP can also address modifiable risk factors and review any medications that might be contributing to elevated uric acid levels.

Does Sildenafil Cause Gout?

There is no established clinical evidence linking sildenafil directly to the development of gout or acute gout attacks. Gout is not listed as an adverse effect in UK sildenafil Summaries of Product Characteristics (SmPCs), and sildenafil is not included among medications known to increase uric acid levels in NICE guidance on gout (NG219).

The mechanism of action of sildenafil—inhibiting phosphodiesterase type 5 to enhance blood flow—does not interfere with purine metabolism or uric acid production and excretion pathways. Unlike diuretics, low-dose aspirin, or certain immunosuppressants that are recognised triggers for hyperuricaemia and gout, sildenafil does not affect kidney function in ways that would impair uric acid elimination in individuals with normal renal function.

Review of the known adverse effects profile of sildenafil, as documented in post-marketing surveillance and clinical trials, does not identify gout as a common or recognised side effect. The most frequently reported adverse reactions relate to the medication's vasodilatory effects, including headaches, flushing, and nasal congestion, rather than metabolic complications affecting uric acid levels.

Important considerations:

• If you are taking sildenafil and develop symptoms suggestive of gout, this is more likely coincidental rather than causally related

• Many men prescribed sildenafil for erectile dysfunction are in age groups (over 40) where gout prevalence naturally increases

• Shared risk factors such as cardiovascular disease, hypertension, obesity, and metabolic syndrome are common to both erectile dysfunction and gout, which may explain why some patients experience both conditions

• Certain medications used alongside sildenafil (such as diuretics for blood pressure) are known gout triggers

• There are no specific interactions between sildenafil and gout medications such as allopurinol or colchicine

• Dose adjustments may be needed for sildenafil in patients with renal or hepatic impairment, which are common in people with gout

If you develop joint pain or swelling whilst taking sildenafil, do not discontinue the medication without medical advice. Instead, consult your GP for proper assessment. They can evaluate whether symptoms represent gout, investigate potential causes, and provide appropriate treatment whilst reviewing your overall medication regimen. There is no established link between sildenafil and gout, and the medication can be safely continued in patients with a history of gout, provided the gout itself is adequately managed with appropriate urate-lowering therapy and lifestyle modifications.

If you suspect any medication is causing side effects, report this through the MHRA Yellow Card scheme.

Frequently Asked Questions