Q: What causes impotence?
A: Impotence occurs from interruption of the physical events that lead to an erection: 1) nerve impulses in the brain, spinal column, and penis, and 2) the response to those impulses by the muscles, fibrous tissues, veins, and arteries affecting the penis. A number of diseases, including diabetes and heart disease, can interrupt this process, and so can some medicines, injuries, and surgical procedures -- for example, prostate surgery that damages nerves and blood vessels in or near the penis.

Q: How is impotence treated? I've heard a lot about sildenafil citrate (Viagra), but I'd like to know what other treatments for impotence are available.
A: As you probably know, Viagra is a pill that is taken around an hour before expected sexual intercourse to improve penis blood flow -- the basis of an erection. Other therapies include psychotherapy; devices that create a vacuum around the penis, causing an inner surge of blood that leads to erection; drugs the man injects into his penis or inserts into the urethra at the tip; and -- if these therapies prove inadequate -- surgery to implant a device to aid erection or to improve blood flow in the penis. As always, your doctor is your best source for specific information about your treatment needs.

Q: How exactly do I use Viagra?
A: The usual dose is one 50 mg tablet taken about one hour before sexual activity. However, it can be taken from 4 to 0.5 hours before sexual activity begins.

Q: What are the side effects of Viagra?
A: The most common side effects are headache, flushing, upset stomach, nasal congestion, diarrhea, and blurred vision.

Q: Is Viagra safe with my other medications? I've heard it may not be safe with heart medicines.
A: You definitely must not take Viagra if you are taking any medications called "nitrates"; these include nitroglycerin in any form and other medications used to relax heart vessels in patients with angina. This combination could result in a dangerously low blood pressure. There are other safety issues as well: Your doctor can explain these and tell you if Viagra is safe for you.

Q: Can women take Viagra?
A: No. Viagra is currently indicated for use in adult men only. However, research is currently being done to evaluate the effectiveness and safety of Viagra in women.

Q: Can Viagra help patients with impotence from any cause?
A: Yes. In clinical studies, Viagra helped impotent men with organic impotence (e.g. diabetes or after prostate surgery), psychological impotence, or both. This improvement was seen regardless of impotence severity or cause and regardless of patient age or race. A recent study also showed benefit in men with impotence due to spinal cord injury. This benefit occurred regardless of whether patients had any erectile function at the start of the study.