Viagra (sildenafil citrate) is a prescription PDE5 inhibitor that can be used for the treatment of male impotence. This condition makes it impossible for you to complete sexual intercourse and can therefore require serious treatment. Viagra is sold online and can be purchased for a lot less money than you would have to spend if you were shopping in the conventional way. Make sure you always talk to your health care provider or read the label carefully to see if any changes need to be made to the dose you were planning to take. Such medical conditions as stomach ulcer, congestive heart failure, leukemia, kidney disease, hemophilia, liver disease, coronary artery disease, high or low blood pressure, multiple myeloma, heart rhythm problems, sickle cell anemia, condition of the eye, a recent history of a heart attack or stroke, or physical deformity of the penis may affect the dose you are prescribed. Make sure you never share your dose of Viagra with other people to whom it was not prescribed, as otherwise there is a risk they may not benefit from the treatment as much as you are. Viagra is not expected to work for you if you do not take it regularly - so make sure you always discuss with your doctor any problems that may occur and any additional information you are interested in.