Sildenafil (Viagra) is a tablet that's taken by mouth for erectile dysfunction (ED) in adults. It works as a phosphodiesterase-5 (PDE5) inhibitor to help people get an erection or keep an erection that lasts for sex. This guide breaks down typical doses, timing, and adjustments to help you use sildenafil safely and effectively. Sildenafil, a phosphodiesterase type 5 (PDE5) inhibitor, works by increasing blood flow to the penis, which helps achieve and maintain an erection in men experiencing erectile dysfunction. Sildenafil is used to treat erectile dysfunction in adult men or pulmonary arterial hypertension in adults and children, depending on the brand or formulation. Includes sildenafil side effects, interactions, and indications. Includes Sildenafil indications, dosage/administration, pharmacology, mechanism/onset/duration of action, half-life, dosage forms, interactions, warnings, adverse reactions, off-label uses and more. Sildenafil is used to treat erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called phosphodiesterase 5 (PDE5) inhibitors. Sildenafil oral tablet is a prescription medication used to treat erectile dysfunction (ED) and pulmonary arterial hypertension (PAH). Viagra (sildenafil) is used to treat erectile dysfunction or impotence in men. Includes Viagra side effects, interactions and indications. 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. Sildenafil, sold under the brand name Viagra among others, is a medication used to treat erectile dysfunction and pulmonary arterial hypertension. [4][8] It is also sometimes used off-label for the treatment of certain symptoms in secondary Raynaud's phenomenon. [9] Find patient medical information for Sildenafil (Viagra, Revatio) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings.