What is Viagra

Viagra relaxes muscles found in the walls of blood vessels and increases blood flow to particular areas of the body.
Viagra is used to treat erectile dysfunction (impotence) in men. Another brand of sildenafil is Revatio, which is used to treat pulmonary arterial hypertension and improve exercise capacity in men and women.

You should not use Viagra if you are allergic to sildenafil, or:

if you take other medicines to treat pulmonary arterial hypertension, such as riociguat (Adempas).
if you take nitrates. Do not take Viagra if you are also using a nitrate drug for chest pain or heart problems. This includes nitroglycerin, isosorbide dinitrate, and isosorbide mononitrate.

Nitrates are also found in some recreational drugs such as amyl nitrate or nitrite (“poppers”). Taking sildenafil with a nitrate medicine can cause a sudden and serious decrease in blood pressure.

To make sure Viagra is safe for you, tell your doctor if you have ever had:

Heart disease or heart rhythm problems, coronary artery disease;
A heart attack, stroke, or congestive heart failure;
High or low blood pressure;
Liver or kidney disease;
A blood cell disorder such as sickle cell anemia, multiple myeloma, or leukemia;
A bleeding disorder such as hemophilia;
A stomach ulcer;
Retinitis pigmentosa (an inherited condition of the eye);
a physical deformity of the penis (such as Peyronie’s disease); or if you have been told you should not have sexual intercourse for health reasons.