Sildenafil is in a class of medications called phosphodiesterase PDE inhibitors. Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient. To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and site usage information with other information we have about you. What side effects can this medication cause? How should this medicine be used?Sildenafil oral tablet is available as a brand-name drug and as a generic drug. Brand names: Viagra, Revatio. Sildenafil comes in three forms: an oral tablet, an . Sildenafil is in a class of medications called phosphodiesterase (PDE) inhibitors. Sildenafil treats erectile dysfunction by increasing blood flow to the penis during sexual .  · Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called phosphodiesterase .