2Viagra is a prescription medication that is used to treat the active ingredient in Viagra is sildenafil citrate, which is a blue tablet. It's taken roughly an hour before sex by men who have erectile dysfunction to help them get and keep an erection. Contrary to popular belief, Viagra is not an aphrodisiac; in order to develop an erection, a man must be sexually aroused. Viagra is commonly available in three dosages: 25mg, 50mg, and 100mg. Which dosage to take depends on the individual, and your doctor may need to adjust your dosage. To comprehend what Viagra is and how it functions, you must first comprehend how a man obtains an erection. When the penis is stimulated, it transmits signals to the brain, which causes cGMP to be released. This substance causes particular muscle cells in the penis' erectile tissue to relax, allowing more blood to flow to that location. The body releases an enzyme called PDE-5 after ejaculation that breaks down cGMP, resulting in erection loss. PDE-5 is inhibited by Viagra and other ED medications, which increases blood flow to the penis and makes it easier to get and keep an erection.