“Sildenafil” — answers to the main questions

Disclaimer: This article is for informational purposes only and does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider regarding any questions about medications or health conditions.

Frequently asked questions

What is sildenafil?

Sildenafil is a prescription medication best known for treating erectile dysfunction (ED). It belongs to a group of drugs called phosphodiesterase type 5 (PDE5) inhibitors. In some cases, it is also prescribed for pulmonary arterial hypertension (PAH) under different brand names and dosages.

How does sildenafil work in the body?

The drug increases blood flow by relaxing blood vessels. In erectile dysfunction, it enhances blood flow to the penis during sexual stimulation. For pulmonary hypertension, it helps relax blood vessels in the lungs, reducing pressure and improving exercise capacity.

Why does erectile dysfunction happen?

ED can be caused by cardiovascular disease, diabetes, hormonal imbalance, neurological disorders, stress, anxiety, or certain medications. Because erection depends on proper blood flow and nerve function, any disruption may contribute. Lifestyle factors such as smoking and obesity also increase risk.

How do you recognize erectile dysfunction?

Common signs include difficulty achieving or maintaining an erection sufficient for sexual activity. Occasional problems are common, but persistent issues lasting several weeks or months may indicate ED. Emotional distress and reduced sexual confidence often accompany it.

How quickly does sildenafil work?

For ED, sildenafil usually starts working within 30–60 minutes. Sexual stimulation is required for the medication to be effective. Its effects generally last up to 4 hours, although this varies between individuals.

Is sildenafil safe?

For most people, sildenafil is safe when used as prescribed. However, it can cause side effects such as headache, flushing, nasal congestion, dizziness, or upset stomach. It may not be safe for people taking nitrates or with certain heart conditions.

What are the dangers or serious side effects?

Rare but serious risks include sudden vision or hearing loss, chest pain, severe allergic reactions, and priapism (an erection lasting more than 4 hours). These require immediate medical attention. Mixing sildenafil with nitrates can cause a dangerous drop in blood pressure.

Can sildenafil be taken every day?

Some treatment plans may involve regular use, but this depends on individual health status and medical supervision. Daily use should only be decided by a healthcare professional. Self-adjusting frequency is not recommended.

Does sildenafil increase sexual desire?

No. Sildenafil improves the physical response (erection) but does not directly increase libido. Sexual desire is influenced by psychological, hormonal, and relationship factors.

Can women take sildenafil?

Sildenafil is not routinely approved for female sexual dysfunction. However, it is prescribed for pulmonary arterial hypertension in both men and women. Any off-label use should be discussed with a physician.

When should you see a doctor about ED?

You should consult a doctor if erectile difficulties persist for more than a few weeks, worsen over time, or are associated with other symptoms like chest pain or shortness of breath. ED can be an early sign of cardiovascular disease.

Can sildenafil be combined with alcohol?

Small amounts of alcohol may not significantly affect the drug, but excessive drinking can reduce effectiveness and increase side effects such as dizziness or low blood pressure. Moderation is strongly advised.

Detailed breakdown

1. Mechanism of action and pharmacology

Sildenafil works by inhibiting the PDE5 enzyme, which regulates blood flow in certain tissues. By blocking PDE5, the medication increases levels of cyclic guanosine monophosphate (cGMP), leading to smooth muscle relaxation and improved circulation.

It does not cause spontaneous erections — sexual stimulation triggers nitric oxide release, which starts the cascade. Understanding this mechanism helps clarify why the medication may not work without arousal.

2. Indications: erectile dysfunction and pulmonary hypertension

The most common indication is erectile dysfunction. ED may be vascular, neurological, hormonal, or psychological in origin. Because blood vessel health is central, ED can sometimes signal broader cardiovascular risk.

Sildenafil is also used in pulmonary arterial hypertension to improve exercise tolerance. In this context, dosing and monitoring differ significantly from ED treatment.

For more about vascular health and prevention strategies, see our cardiovascular health section.

3. Safety profile, contraindications and interactions

Sildenafil should not be used with nitrate medications (often prescribed for angina) due to the risk of severe hypotension. Caution is required in individuals with recent stroke, heart attack, unstable angina, severe liver impairment, or certain retinal disorders.

Drug interactions may occur with alpha-blockers, some antifungals, HIV protease inhibitors, and other medications affecting liver enzymes. Always inform your healthcare provider about all substances you take.

You can also explore medication safety principles in our pharmacology and drug safety guide.

4. Side effects and warning signs

Most adverse effects are mild and temporary. Headache, flushing, indigestion, and nasal congestion are common. Visual disturbances (blue-tinted vision or light sensitivity) may occur in some cases.

Emergency symptoms include chest pain, fainting, severe dizziness, sudden hearing or vision loss, and erections lasting more than four hours. Prompt medical evaluation is crucial in these situations.

5. Psychological and lifestyle factors

Medication alone may not fully resolve erectile dysfunction. Stress, depression, anxiety, sleep disorders, and relationship problems can all contribute. Lifestyle changes — such as regular physical activity, weight management, smoking cessation, and reduced alcohol intake — can significantly improve outcomes.

Read more about holistic approaches in our men’s health and lifestyle section.

Checklist: what you can do today

• Schedule a medical consultation if erectile problems persist.
• Review all current medications with your doctor for potential interactions.
• Monitor blood pressure and cardiovascular risk factors.
• Adopt regular physical activity suited to your health status.
• Limit alcohol consumption.
• Stop smoking if applicable.
• Manage stress through sleep hygiene and relaxation techniques.
• Maintain open communication with your partner.
• Seek psychological support if anxiety or depression is present.
• Follow medical instructions precisely if sildenafil is prescribed.

When is it urgent? (Symptom → urgency → where to seek help)

Sources

• U.S. Food and Drug Administration (FDA) — Drug Safety Communications and prescribing information.
• European Medicines Agency (EMA) — Public assessment reports for sildenafil-containing medicines.
• National Institutes of Health (NIH), MedlinePlus — Sildenafil drug information.
• American Urological Association (AUA) — Guidelines on Erectile Dysfunction.
• European Society of Cardiology (ESC) — Guidelines on cardiovascular disease prevention.
• World Health Organization (WHO) — Essential medicines and pharmacovigilance resources.