Viagra relaxes muscles found in the walls of blood vessels and increases blood
flow to particular areas of the body.

Viagra is used to treat erectile dysfunction (impotence) in men. Another brand
of sildenafil is Revatio, which is used to treat pulmonary arterial
hypertension and improve exercise capacity in men and women. This page
contains specific information for Viagra, not Revatio.

Do not take Viagra while also taking Revatio, unless your doctor tells you to.





Get emergency medical help if you have **signs of an allergic reaction to
Viagra:** hives; difficulty breathing; swelling of your face, lips, tongue, or
throat.

**Stop taking Viagra and get emergency medical help if you have:**

  * heart attack symptoms--chest pain or pressure, pain spreading to your jaw or shoulder, nausea, sweating;

  * vision changes or sudden vision loss; or

  * erection is painful or lasts longer than 4 hours (prolonged erection can damage the penis).

Call your doctor at once if you have:

  * ringing in your ears, or sudden hearing loss;

  * irregular heartbeat;

  * swelling in your hands, ankles, or feet;

  * shortness of breath;

  * seizure (convulsions); or

  * a light-headed feeling, like you might pass out.

Common Viagra side effects may include:

  * flushing (warmth, redness, or tingly feeling);

  * headache, dizziness;

  * abnormal vision (blurred vision, changes in color vision)

  * runny or stuffy nose, nosebleeds;

  * sleep problems (insomnia);

  * muscle pain, back pain; or

  * upset stomach.

This is not a complete list of side effects and others may occur. Call your
doctor for medical advice about side effects. You may report side effects to
FDA at 1-800-FDA-1088.

Viagra side effects (more detail)