Sildenafil

Sildenafil is a prescription medication primarily used to treat erectile dysfunction (ED) in men. It works by increasing blood flow to the penis during sexual stimulation, helping to achieve and maintain an erection.

Originally developed to treat high blood pressure and angina, Sildenafil belongs to a class of drugs known as phosphodiesterase type 5 (PDE5) inhibitors. It is also available under the brand name Viagra.

Sildenafil is primarily used to treat:

• Erectile dysfunction (ED)
• Pulmonary arterial hypertension (PAH) (under brand name Revatio)
• Off-label: Raynaud’s phenomenon, altitude sickness

Common side effects of Sildenafil:

• Headache
• Flushing (warmth or redness in face)
• Upset stomach
• Nasal congestion
• Dizziness
• Vision changes (blurred vision, sensitivity to light)

Tablets: 25 mg, 50 mg, and 100 mg.


The typical starting dose for ED is 50 mg, taken as needed about 30–60 minutes before sexual activity.

Sildenafil should be taken orally, usually 30 to 60 minutes before sexual activity. Do not take more than once per day.

• Swallow with water
• Can be taken with or without food (avoid high-fat meals)
• Follow your doctor’s dosage instructions

Sildenafil should not be used with certain medications or conditions, especially nitrates, due to the risk of a dangerous drop in blood pressure. Avoid if you have:

• Recent heart attack or stroke
• Uncontrolled low or high blood pressure
• Severe liver or kidney disease
• Retinitis pigmentosa
• Are taking nitrates or nitric oxide donors