Common use

Viagra is used to treat erectile dysfunction (impotence) in men. Viagra relaxes muscles found in the walls of blood vessels and increases blood flow to particular areas of the body.

Dosage and direction

Take Viagra exactly as it was prescribed for you. Do not take this medicine in larger or smaller amounts or for longer than recommended. Viagra is usually taken only when needed, 30 minutes to 1 hour before sexual activity. You may take it up to 4 hours before sexual activity. Do not take Viagra more than once per day. Viagra can help you have an erection when sexual stimulation occurs. An erection will not occur just by taking a pill.

Precautions

To make sure Viagra is safe for you, tell your doctor if you have ever had: heart disease or heart rhythm problems, coronary artery disease; a heart attack, stroke, or congestive heart failure; high or low blood pressure; liver or kidney disease; a blood cell disorder such as sickle cell anemia, multiple myeloma, or leukemia; a bleeding disorder such as hemophilia; a stomach ulcer; retinitis pigmentosa (an inherited condition of the eye); a physical deformity of the penis (such as Peyronie's disease); or if you have been told you should not have sexual intercourse for health reasons.
Drinking alcohol with this medicine can cause side effects.
Grapefruit and grapefruit juice may interact with sildenafil and lead to unwanted side effects. Avoid the use of grapefruit products while taking sildenafil.
Avoid using any other medicines to treat impotence, such as alprostadil or yohimbine, without first talking to your doctor.

Contraindications

You should not use Viagra if you are allergic to sildenafil, or: if you take other medicines to treat pulmonary arterial hypertension, such as riociguat (Adempas); if you take nitrates.
Do not take Viagra if you are also using a nitrate drug for chest pain or heart problems. This includes nitroglycerin, isosorbide dinitrate, and isosorbide mononitrate. Nitrates are also found in some recreational drugs such as amyl nitrate or nitrite ("poppers"). Taking sildenafil with a nitrate medicine can cause a sudden and serious decrease in blood pressure.

Possible side effect

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).
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.

Drug interaction

Do not take Viagra with similar medications such as avanafil (Stendra), tadalafil (Cialis) or vardenafil (Levitra). Tell your doctor about all other medications you use for erectile dysfunction.
Tell your doctor about all your current medicines and any you start or stop using, especially: drugs to treat high blood pressure or a prostate disorder; an antibiotic - clarithromycin, erythromycin, or telithromycin; antifungal medicine - ketoconazole or itraconazole; or medicine to treat HIV/AIDS - atazanavir, indinavir, ritonavir, or saquinavir; nitrates; medications used to treat pulmonary artery hypertension.

Missed dose

Since Viagra is used as needed, you are not likely to miss a dose.

Overdose

Seek emergency medical attention.

Storage

Store at room temperature away from moisture and heat. Keep away from children.