Sildenafil citrate, sold under the name Viagra is the first of a new group of medication which allows adequate sexual stimulation, relaxes the blood vessels of the penis and helps erection. It can help many men who have erectile dysfunction get and keep an erection when they become sexually excited (stimulated). Viagra tablet should be taken once a day. The time necessary for Viagra to exercise its action is about half an hour. The effect is maintained for about 4 hours.
Viagra belongs to the substance group of selective phosphodiesterase inhibitors and develops its effect by directly promoting blood circulation in the penis.
The effect is only obtained with a satisfactory sexual stimulation.