Sildenafil relaxes muscles within the penis. This allows increased blood flow into the penis, necessary to achieve and maintain an erection.

Sildenafil is used to treat erectile dysfunction (impotence).

Sildenafil may also be used for purposes other than those listed in this medication guide.

Special precautions

Before taking sildenafil, tell your doctor if you

• have had a heart attack, stroke, or life-threatening irregular heartbeats within the last six months;

• have a history of heart failure;
• have coronary artery disease;
• have angina;
• have high or low blood pressure;
• have liver problems;
• have kidney problems;
• have ever had blood problems, including sickle cell anemia or leukemia;
• have a bleeding disorder;
• have a stomach ulcer;
• have retinitis pigmentosa (an inherited condition of the eye);
• have a physical deformity of the penis such as Peyronie's disease;
• have a condition that could lead to prolonged and painful erections, such as a tumor of the bone marrow, sickle cell anemia, or leukemia; or
• are taking another medicine to treat impotence, such as alprostadil (Caverject, Muse, Edex) or yohimbine (Yocon, Yodoxin, others)

Although sildenafil is not indicated for use by women, it is in the FDA pregnancy category B. This means that sildenafil is not expected to be harmful to an unborn baby. Sildenafil should not be taken by women.

It is not known whether sildenafil passes into breast milk. Sildenafil should not be taken by women. If you are over 65 years of age, you may be more likely to experience side effects from sildenafil. Your doctor may prescribe a lower dose of this medication.

Side effects

If you experience any of the following serious side effects, stop taking sildenafil and seek emergency medical attention or notify your doctor immediately:

• an allergic reaction (difficulty breathing; closing of the throat; swelling of the lips, tongue, or face; or hives);

• chest pain or an irregular heartbeat;
• swelling of the ankles or legs;shortness of breath;
• prolonged or severe dizziness;
• a prolonged (lasting longer than 4 hours) or painful erection; or
• dizziness, nausea, or angina (pain, tightness, discomfort, numbness, or tingling in the chest, arms, neck, or jaw)

Other, less serious side effects may be more likely to occur. Continue to take sildenafil and talk to your doctor if you experience

• flushing;

• mild dizziness;
• headache;
• nasal congestion;
• diarrhea;
• temporary blue tint in vision or other vision abnormalities; or
• itching or a rash

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome. Keep all appointments with your doctor. Don’t let anyone else take your medicines.