Viagra pills. Computer artwork of viagra pills, the first oral treatment for male impotence, in front of the rising sun. Viagra is the trade name for the drug sildenafil citrate. It is used to treat erectile dysfunction. Viagra enhances the smooth muscle relaxant effects of nitric oxide, a chemical that is released in response to sexual stimulation. Relaxation of the smooth muscle allows blood to enter the penis, resulting in erection. Viagra is made by Pfizer pharmaceuticals.