Viagra was the first FDA-approved medication used to treat erection problems in men. When a man cannot get or maintain an erection for sexual activity, it’s called erectile dysfunction. Viagra works by blocking an enzyme called PDE-5, which boost the amount of nitric oxide in the system. Nitric oxide causes the muscles in the penis to relax, increasing blood flow and facilitating an erection.
Viagra stays in your bloodstream for 4 to 6 hours, making it much easier to achieve an erection for sexual intercourse. For Viagra to work, you must be sexually stimulated. Contrary to what you might think, you don’t get an erection just from taking the pill.
Since Viagra affects nitric oxide levels, do not take Viagra if you use nitrate drugs to treat cardiovascular problems. Taking Viagra with nitrate drugs can cause a sudden, dangerous drop in blood pressure. Only take Viagra as prescribed by your doctor.