Sildenafil is a prescription medication used to treat erectile dysfunction (impotence) in men.
Sildenafil is a phosphodiesterase 5 (PDE5) inhibitor that prevents the enzyme PDE5 from breaking down cGMP too quickly. This increases blood flow to the penis during sexual stimulation, helping to achieve and maintain an erection. It requires physical stimulation to work and does not cause an erection on its own.
Effects typically begin within 30 minutes after taking the dose and can last up to 4 hours, though the action may diminish after 2 hours.