Just when you thought the four leading erectile dysfunction pills were plenty to keep men flying at full staff, there's another drug that's recently come on the market. It's called Stendra, and much like its predecessors Viagra, Cialis, Levitra and Staxyn, Stendra works to increase blood flow to the penis and cause an erection. They all seem to take effect within 30 minutes, though the staying power may vary - Viagra lasts about four hours, while Levitra lasts about five hours. And men who take Cialis may expect to gain an erection upon arousal during the course of 36 hours. Stendra may last up to six hours. But if your man is taking one of these pills, does he really know why or what the risks are? First, consider his health. Men with certain conditions like heart disease, diabetes and obesity sometimes experience erectile dysfunction as a result of these conditions, and once they're kept under control, function may return. However, if he's being treated for high blood pressure, takes nitroglycerin to control chest pain or is scheduled for surgery, including dental surgery, then taking ED pills may not be a good idea. Common side effects include headache, facial flushing and upset stomach. Less common and more dangerous side effects include chest pain, rash, painful erection, and itching or burning during urination. A problem called NAION -- nonarteritic anterior ischemic optic neuropathy - that results in vision loss can occur in men who smoke, have heart disease, diabetes, high blood pressure or are over the age of 50. Contact a health care provider right away if you experience sudden vision loss or any other symptoms. Finally, obtain ED pills only under the guidance and prescription of a doctor - never obtain them online because the quality cannot be controlled.