What is sildenafil?
Sildenafil (brand name: Viagra) is a medicine that doctors prescribe to help men who have erectile dysfunction have sex. Erectile dysfunction is the inability of the penis to become rigid (hard), or to stay rigid long enough to finish having sex. Sildenafil helps maintain an erection.

How should I take sildenafil?
Follow your doctor's instructions. Usually, a man takes 1 tablet 30 minutes to 1 hour before he plans to have sex. You should not take more than 1 tablet in 24 hours. The medicine comes in tablets of 25 mg, 50 mg and 100 mg. Most patients start with 50 mg.

Even if you take sildenafil, you still need physical and mental stimulation and desire to have an erection. If your first dose of Viagra doesn't help, call your doctor. Your doctor may want to change your tablet strength.

What are the side effects?
Sildenafil has some common side effects:

* Headache
* Flushing (face and upper body turning red and warm)
* Stomach upset
* Runny nose (sniffles)
* Vision changes (things look blue)

Headache is the most common side effect. Vision changes are the least common. Talk to your doctor if you have any side effect that bothers you.

Call your doctor right away if you take sildenafil and have a prolonged erection that lasts 4 hours or longer. This condition may cause permanent impotence if not treated.

Can everyone use sildenafil?
No. You shouldn't use this medicine if you take nitroglycerin or any other nitrates for chest pain. If you have heart problems, tell your doctor before taking sildenafil. This medicine can have serious side effects in people who have heart problems.

If you use sildenafil and get chest pains, be sure to tell the paramedics, nurses or doctors at the hospital that you use it and when you used it last.

You also shouldn't take sildenafil if you are taking other medicines for erectile dysfunction.
 

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