sentences:  There are no clinical trials or scientific studies that support the effectiveness of any of these ingredients for the treatment of erectile dysfunction and some products have been found to contain drugs and other adulterants, and have been the subject of FDA and FTC warnings and actions to remove them from the market.The name "herbal viagra" is taken from the brand name Viagra, under which drug company Pfizer sells sildenafil citrate, a drug that is used to treat erectile dysfunction.Viagra has become a generic term for many people discussing drugs designed to treat erectile dysfunction, even those which do not contain sildenafil.