What is sildenafil? Sildenafil relaxes muscles of the blood vessels and increases blood flow to particular areas of the body. Sildenafil under the name 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. Do not take Viagra while also taking Revatio. Warnings Do not take sildenafil if you are also using a nitrate drug for chest pain or heart problems, including nitroglycerin, isosorbide dinitrate, isosorbide mononitrate, and some recreational drugs such as "poppers". Taking sildenafil with a nitrate medicine can cause a sudden and serious decrease in blood pressure. Some medicines can cause unwanted or dangerous effects when used with sildenafil. Tell your doctor about all your current medicines, especially riociguat (Adempas). Do not take sildenafil with riociguat. Contact your doctor or seek emergency medical attention if your erection is painful or lasts longer than 4 hours. A prolonged erection (priapism) can damage the penis. Stop using sildenafil and get emergency medical help if you have sudden vision loss. Before taking this medicine You should not use sildenafil if you are allergic to it, or: if you take other medicines to treat pulmonary arterial hypertension, such as riociguat (Adempas). Do not take this medicine 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. To make sure sildenafil is safe for you, tell your doctor if you have ever had: heart problems (chest pain, a heart rhythm disorder, heart attack); high or low blood pressure; blood circulation problems; retinitis pigmentosa (an inherited condition of the eye); blindness in one or both eyes; bleeding problems; a stomach ulcer; pulmonary veno-occlusive disease (PVOD); liver or kidney disease; a blood cell disorder such as sickle cell anemia, multiple myeloma, or leukemia; 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. Sildenafil can decrease blood flow to the optic nerve of the eye, causing sudden vision loss. This has occurred in a small number of people taking sildenafil, most of whom also had heart disease, diabetes, high blood pressure, high cholesterol, or certain pre-existing eye problems, and in those who smoked or were over 50 years old. It is not clear whether this medicine is the actual cause of vision loss. This medicine is not expected to harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant. Women with pulmonary arterial hypertension should not stop taking sildenafil without talking to their doctor. It is not known whether sildenafil passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby. Women with pulmonary arterial hypertension should not stop taking sildenafil without talking to their doctor. Do not give this medication to anyone under 18 years old without medical advice. How should I take sildenafil? Take sildenafil exactly as it was prescribed for you. Follow all directions on your prescription label and read all medication guides or instruction sheets. Revatio is usually taken three times each day, about 4 to 6 hours apart. 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. Shake the oral suspension (liquid) before you measure a dose. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon). Viagra can help you have an erection when sexual stimulation occurs. An erection will not occur just by taking a pill. Follow your doctor's instructions. During sexual activity, if you become dizzy or nauseated, or have pain, numbness, or tingling in your chest, arms, neck, or jaw, stop and call your doctor right away. You could be having a serious side effect of sildenafil. Store at room temperature away from moisture and heat.   What happens if I miss a dose? Since Viagra is used as needed, you are not likely to miss a dose. If you miss a dose of Revatio, take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time. What happens if I overdose? Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. What to avoid Drinking alcohol with sildenafil can cause side effects. Grapefruit may interact with sildenafil and lead to unwanted side effects. Avoid the use of grapefruit products. Avoid using any other medicines to treat impotence, such as alprostadil or yohimbine, without first talking to your doctor. Sildenafil side effects Get emergency medical help if you have signs of an allergic reaction to sildenafil: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Stop taking sildenafil 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; erection is painful or lasts longer than 4 hours (prolonged erection can damage the penis); 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 sildenafil side effects may include: flushing (warmth, redness, or tingly feeling); headache, dizziness; heartburn, nausea, or upset stomach abnormal vision (blurred vision, changes in color vision) runny or stuffy nose, nosebleeds; sleep problems (insomnia); or muscle pain, back pain. 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.   What other drugs will affect sildenafil? Do not take sildenafil with similar medications such as avanafil (Stendra), tadalafil (Cialis) or vardenafil (Levitra). Tell your doctor about all other medications you use for erectile dysfunction. Do not take sildenafil if you take other medicines to treat pulmonary arterial hypertension, such as riociguat (Adempas). Do not take sildenafil 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. In addition, tell your doctor about all your other medicines, especially: drugs to treat high blood pressure or a prostate disorder; antifungal medicine - ketoconazole or itraconazole; or medicine to treat HIV/AIDS - ritonavir and others. This list is not complete. Other drugs may interact with sildenafil, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

What is tadalafil? Tadalafil relaxes muscles of the blood vessels and increases blood flow to particular areas of the body. Tadalafil under the name of Cialis is used to treat erectile dysfunction (impotence) and symptoms of benign prostatic hypertrophy (enlarged prostate). Another brand of tadalafil is Adcirca, which is used to treat pulmonary arterial hypertension and improve exercise capacity in men and women. Warnings Do not take tadalafil if you are also using a nitrate drug for chest pain or heart problems, including nitroglycerin, isosorbide dinitrate, isosorbide mononitrate, and some recreational drugs such as "poppers". Taking tadalafil with a nitrate medicine can cause a sudden and serious decrease in blood pressure. Some medicines can cause unwanted or dangerous effects when used with tadalafil. Tell your doctor about all your current medicines, especially riociguat (Adempas). Contact your doctor or seek emergency medical attention if your erection is painful or lasts longer than 4 hours. A prolonged erection (priapism) can damage the penis. Get medical help at once if you have nausea, chest pain, or dizziness during sex. Stop using tadalafil and get emergency medical help if you have sudden vision loss. Before taking this medicine You should not take tadalafil if you are allergic to it. Taking tadalafil with certain other medicines can cause a sudden and serious decrease in blood pressure. Do not take this medicine if you also use: riociguat (to treat pulmonary arterial hypertension); or a nitrate drug (for chest pain or heart problems) such as nitroglycerin, isosorbide dinitrate, isosorbide mononitrate, or recreational drugs such as amyl nitrate or nitrite "poppers". Some tadalafil can remain in your bloodstream for 2 or more days after each dose you take (longer if you have liver or kidney disease). Avoid nitrate use during this time. To make sure this medicine is safe for you, tell your doctor if you have ever had: heart disease or heart rhythm problems; a heart attack or stroke; angina (chest pain), high or low blood pressure; pulmonary hypertension (unless you are taking tadalafil for this); a condition called pulmonary veno-occlusive disease (narrowing of the veins that carry blood from the lungs to the heart); liver or kidney disease (or if you are on dialysis); vision loss, or retinitis pigmentosa (an inherited condition of the eye); a bleeding disorder; a blood cell disorder such as sickle cell anemia, multiple myeloma, or leukemia; a physical deformity of the penis (such as Peyronie's disease), or an erection lasting longer than 4 hours; a stomach ulcer; or health problems that make sexual activity unsafe. Sudden vision loss has occurred in a small number of people taking medicines like tadalafil (Viagra or others). Most of these people already had certain eye problems or risk factors for blood vessel disorders (heart disease, diabetes, high blood pressure, high cholesterol, coronary artery disease, smoking, or being over 50 years old). It is not clear whether the medicine was the actual cause of vision loss. Sudden hearing loss has also been reported with tadalafil. Stop tadalafil and call your doctor immediately for any hearing loss, decrease in hearing, or ringing in the ears. Do not start or stop taking tadalafil during pregnancy without your doctor's advice. Having pulmonary arterial hypertension (PAH) during pregnancy may cause heart failure, stroke, or other medical problems in both mother and baby. Tell your doctor right away if you become pregnant. It may not be safe to breastfeed while using tadalafil. Ask your doctor about any risk. Cialis is not for use in women. Tadalafil is not approved for use by anyone younger than 18 years old. How should I take tadalafil? Tadalafil is usually taken only once per day. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended. Tadalafil can be taken with or without food. Do not break or split a Cialis tablet. Swallow it whole. For erectile dysfunction, take Cialis just before sexual activity but not more than once per day. It can be used up to 36 hours before sexual activity. Cialis can help achieve an erection when sexual stimulation occurs. An erection will not occur just by taking a pill. Follow your doctor's instructions. Do not take Cialis for erectile dysfunction if you are taking Adcirca for pulmonary arterial hypertension. Store at room temperature away from moisture and heat.   What happens if I miss a dose? If tadalafil is used as needed, you are not likely to be on a dosing schedule. If you take tadalafil every day and you miss a dose, take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose. What happens if I overdose? Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. What to avoid Drinking alcohol with this medicine can cause a drop in blood pressure, leading to dizziness or fainting. Grapefruit and grapefruit juice may interact with tadalafil and lead to unwanted side effects. Avoid the use of grapefruit products while taking this medicine. Tadalafil side effects Get emergency medical help if you have signs of an allergic reaction to tadalafil: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Stop and get medical help at once if you have nausea, chest pain, or dizziness during sex. You could be having a life-threatening side effect. Stop using tadalafil and call your doctor at once if you have: a light-headed feeling, like you might pass out; an erection is painful or lasts longer than 4 hours (prolonged erection can damage the penis); vision changes or sudden vision loss; ringing in your ears or sudden hearing loss; or heart attack symptoms - chest pain or pressure, pain spreading to your jaw or shoulder, nausea, sweating. Common tadalafil side effects may include: headache; flushing (warmth, redness, or tingly feeling); nausea, upset stomach; stuffy nose; or muscle pain, back pain, pain in your arms, legs, or back. 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.   What other drugs will affect tadalafil? Tell your doctor about all your current medicines and any you start or stop using, especially: medicines to treat erectile dysfunction or pulmonary arterial hypertension; an antibiotic or antifungal medicine; antiviral medicine to treat hepatitis C or HIV/AIDS; drugs to treat high blood pressure or a prostate disorder; or seizure medicine. This list is not complete. Other drugs may interact with tadalafil, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.