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 works by blocking an enzyme in the body called PDE5, which helps relax certain blood vessels. For erectile dysfunction, it increases blood flow to the penis when aroused. The medication, officially known as sildenafil, debuted in 1998. Today, it’s used by millions of men around the world when they want to … well, rise to the occasion during an amorous moment. 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] NHS medicines information on dosage for sildenafil, how to take it and what to do if you miss a dose or take too much. Sildenafil is used to treat erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called phosphodiesterase 5 (PDE5) inhibitors. 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. Sildenafil is used to treat male sexual function problems (impotence or erectile dysfunction-ED). Learn about side effects, drug interactions, dosages, warnings, and more. 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. Sildenafil oral tablet is a prescription medication used to treat erectile dysfunction (ED) and pulmonary arterial hypertension (PAH).