Sildenafil is in a class of medications called phosphodiesterase (PDE) inhibitors.Sildenafil treats erectile dysfunction by increasing blood flow to the penis during sexual stimulation This increased blood flow can cause an erectction.Sildenafil treats PAH by relaxing the blood vessels in the lungs to allow blood to flow easily.
Sildenafil relaxes muscles found in the walls of blood vessels and increases blood flow to particular areas of the body.