Viagra is good drug in limit Health problems !

How does Viagra work in the Human body?
Answered by Dr. Michael Roizen

To help understand how drugs like Viagra work, think about how nitroglycerin works in people with angina. Nitroglycerin is converted to nitric oxide, which opens the heart's arteries to allow blood to flow through, which gives you pain relief. Only nitroglycerine selectively dilates the arteries near the heart instead of the ones further south.

Nitroglycerin and Viagra are dangerous together because there's too much dilation and low blood pressure. That can cause you to faint or to have heart problems.

Viagra stimulates the chain reaction that allows blood to flow into the penis by prolonging nitric oxide's effect. Nitric oxide stimulates a chain of events that dilates those arteries so much that the return of blood from the penis through the veins is blocked.

Big caveat: Viagra doesn't cure erectile dysfunction. If you don't treat the underlying cause—be it onion rings, inactivity, or that you smoke more than a five-alarm fire—then you're ultimately never going to fix the problem.

Now, if you have the unfortunate side effect of a cement-hard erection that lasts for more than four hours (yes, we said unfortunate), you do need to see a doctor because it means your penis is probably not getting enough new blood and might be starving to death.
Viagra is generally taken as needed 30 minutes to four hours before sexual activity. The medication comes in the form of a tablet and is taken orally with or without food. Taking Viagra with a meal that is high in fat will cause the medication to take longer to begin working.
Some side effects of Viagra are nosebleeds, flushing, diarrhea, heartburn, difficulty sleeping, stuffy nose, memory problems, back pain, numbness, muscles aching, sensitivity to light, and headache. It is also possible to see color differently. For instance, you may have trouble identifying the colors blue and green. More serious side effects include rash, itching or burning sensation when urinating, blurred vision, sudden hearing loss, sudden vision loss, ringing in the ears, fainting, cheat pain, dizziness, and shortness of breath that worsens, A painful erection lasting for more than four hours is known as priapism and is also a serious side effect of Viagra. If you experience any of the more serious side effects or experience any minor ones that do not go away, you should tell your doctor as soon as possible.