All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:
Diarrhea; dizziness; flushing; headache; heartburn; stuffy nose; upset stomach.
Seek medical attention right away if any of these SEVERE side effects occur:
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); chest pain; fainting; fast or irregular heartbeat; memory loss; numbness of an arm or leg; one-sided weakness; painful or prolonged erection; ringing in the ears; seizure; severe or persistent dizziness; severe or persistent vision changes; sudden decrease or loss of hearing; sudden decrease or loss of vision in one or both eyes.
This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects.
Some medical conditions may interact with sildenafil. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:
if you are pregnant, planning to become pregnant, or are breast-feeding
if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
if you have allergies to medicines, foods, or other substances
if you have a deformed penis (eg, cavernosal fibrosis, Peyronie disease), blood cell problems (eg, leukemia, multiple myeloma, sickle cell anemia), or any other condition that may increase the risk of a prolonged erection (priapism)
if you have a history of a prolonged (more than 4 hours) or painful erection (priapism)
if you have a history of certain eye problems (eg, macular degeneration, optic neuropathy, retinitis pigmentosa, sudden vision loss in one or both eyes) or hearing problems (eg, ringing in the ears, decreased hearing, hearing loss)
if you have a history of liver or kidney problems, lung problems (eg, pulmonary veno-occlusive disease), high or low blood pressure, ulcers, bleeding problems, heart problems (eg, angina, aortic stenosis, heart failure, irregular heartbeat), or blood vessel problems
if you have a history of heart attack, stroke, or life-threatening irregular heartbeat, especially within the past 6 months
Some MEDICINES MAY INTERACT with sildenafil. Tell your health care provider if you are taking any other medicines, especially any of the following:
Alpha-blockers (eg, doxazosin), medicines for high blood pressure, nitrates (eg, isosorbide, nitroglycerin), or nitroprusside because severe low blood pressure with dizziness, lightheadedness, and fainting may occur
Azole antifungals (eg, itraconazole, ketoconazole), H2 antagonists (eg, cimetidine), HIV protease inhibitors (eg, ritonavir, saquinavir), macrolide antibiotics (eg, erythromycin), narcotic analgesics (eg, dihydrocodeine), or telithromycin because they may increase the risk of sildenafil's side effects
Bosentan or rifampin because they may decrease sildenafil's effectiveness
This may not be a complete list of all interactions that may occur. Ask your health care provider if sildenafil may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.