Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called phosphodiesterase 5 (PDE5) inhibitors. These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly.
Viagra is indicated for the treatment of erectile dysfunction in men. Viagra is a phosphodiesterase type 5 (PDE5) inhibitor. It works by helping to increase blood flow into the penis during sexual stimulation. This helps you to achieve and maintain an erection.