The latest Viagra information is unheard of in the history of the pharmaceutical industry. Pfizer, the maker of the drug, says 9 Viagra pills are sold every second . That's about 300 million Viagra tablets a year.

And you can bet most of the men taking Viagra have no idea how it works. All they care about is that it DOES work. And it has improved millions of men's sex lives all over the world since Viagra hit the market about 10 years ago.

But the story of how the little blue pill works is actually quite fascinating. To understand it, you first need to know a bit about erections themselves -- and then we'll get to the nitty gritty Viagra information.

How Your Erection Works

The penis isn't an ordinary organ that uses muscle power to get the job done. It has no muscles, instead using pressurized blood to become erect.

The penis contains two main tubes that fill up with blood. Smaller arteries and blood veins carry the blood in and out of those tubes. The arteries bring the blood in; the veins drain it out.

When the penis is flaccid, the veins that drain blood out remain open so there is a constant circulation of blood.

But when a man becomes sexually excited, the brain sends a message to those veins telling them to tighten up and prevent blood from leaving the organ. It also sends a signal causing the arteries to dilate and let more blood in. The blood pressure in the tubes builds up causing the penis to get harder and longer.

And that's how your erection works. But when it doesn't work, you get...

Erectile Dysfunction

If the arteries and veins don't open and close adequately, a man may not be able to become erect. This is the leading cause of erectile dysfunction and the main reason why men turn to products like Viagra for help.

Viagra Information: How It Really Works

From the large amount of Viagra information that's been published, we now know that the scientists who developed the drug faced a major challenge. They had to find a chemical that affects blood circulation in the penis only and not other parts of the body. And how they did that was ingeniously simple.

To follow along, you need to know the names of two important natural body chemicals:

cGMP causes blood flow to the penis to increase.
PDE 5 is an enzyme that deactivates the cGMP.

The body has 11 different kinds of PDE enzymes but only PDE 5 is found in the penis. So scientists realized that if they could block PDE 5 selectively, it would allow the crucial cGMP to do its work better and let more blood into the penis. Which would allow men with ED to have better erections.

So Pfizer started looking for a chemical that would target specifically PDE 5. They discovered that sildenafil citrate disables the PDE 5 enzyme, allowing the cGMP to build up blood pressure in the penis for a few hours before wearing off. And that's how Viagra was born.

So now you know exactly how Viagra alters the body's chemicals to give millions of men better erections and more satisfying sex lives.

Viagra Information Resources:

For more Viagra information, please visit our Men's Health Information Center.

To order Viagra, visit the Viagra Information and Ordering page .

For Viagra information from the manufacturer, visit Pfizer's Viagra website.

Read the FDA's Viagra Information Sheet.