Common uses
This medicine is a phosphodiesterase inhibitor used to treat sexual function problems such as impotence or erectile dysfunction. In combination with sexual stimulation, this medicine works by helping the blood flow into the penis to achieve and maintain an erection. This medicine is not intended for use in women or children. This medicine will not protect against sexually transmitted diseases including HIV infection. Use "safe sex" practices such as latex condoms.

Before using
Do not take his medicine if you are also taking or using nitroglycerin, (e.g., tablet, patch, or ointment dose forms) or other nitrates (e.g., isosorbide), nitroprusside (or any "nitric oxide donor" medicine), or recreational drugs called "poppers" containing amyl or butyl nitrate because very serious interactions may occur. If you are not sure whether a certain medicine is a nitrate, contact your doctor or pharmacist. If you are currently using any of these medicines, tell your doctor or pharmacist before using sildenafil.

Additional monitoring of your dose or condition may be needed if you are taking other medicines for impotence, azole antifungals (e.g., itraconazole, ketoconazole), cimetidine, erythromycin, mibefradil, rifamycins (e.g., rifampin), high blood pressure medicines, or delavirdine. If you are taking an HIV protease inhibitor (e.g., ritonavir, saquinavir), do not take more than a 25 mg dose of sildenafil in a 48-hour period. If you are taking more than a 25 mg dose of sildenafil and are also taking an alpha-blocker medicine (e.g., doxazosin, prazosin, terazosin) for various conditions (e.g., enlarged prostate), separate the time between taking these medicines by more than 4 hours. See How To Use section for drug-food interaction information.

Do not start or stop any medicine without doctor or pharmacist approval. Inform your doctor of any other medical conditions including penis conditions (e.g., angulation, fibrosis/scarring, Peyronie's disease), history of painful/prolonged erection (priapism), sickle cell anemia, blood system cancers (e.g., leukemia or myeloma), eye problems (e.g., retina diseases like retinitis pigmentosa), kidney or liver disease, bleeding disorders, active stomach ulcers, heart problems (e.g., recent heart attack or serious arrhythmia within past 6 months, heart failure, coronary artery disease with unstable angina, aortic stenosis, idiopathic hypertrophic subaortic stenosis), recent stroke within past 6 months, very high or low blood pressure, or allergies.

Directions
Take this medicine by mouth as needed between four hours and one-half hour before sexual activity (about 1 hour before is most effective); or take as directed by your doctor. Do not take this medicine more often than once daily as needed. A high fat meal may delay the time of onset of this medicine.

Avoid eating grapefruit or drinking grapefruin juice while being treated with this medicine unless your doctor instructs you otherwise. Your dosage is based on your medical condition, your response to therapy, and other medicines you are taking (see also Before Using section).

Store this medicine at room temperature 77 degrees F (25 degrees C) in a tightly-closed container, away from heat, moisture, and light. Brief storage between 59 and 86 degrees F (15 and 30 degrees C) is permitted.

Cautions
Do not take this medicine if you have had an allergic reaction to it or are allergic to any ingredient in this product. This medicine may rarely cause dizziness or vision changes. Do not drive, operate machinery, or do anythind else that could be dangerous until you know how you react to this medicine. Using this medicine alone, with other medicines, or with alcohol may lessen your ability to drive or to perform other potentially dangerous tasks. To minimize dizziness or lightheadness, sit up or stand slowly when rising from a seated or lying position. Alcohol may increase your risk for side effects, including headache, dizziness, or lightheadedness. Avoid excessive amounts of alcohol when using this medicine.

Do not exceed the recommended doze without checking with your doctor. Rarely, this medicine may change heart rhythm, especially if taken with other medicines that can change the heart rhythm. This change in heart rhythm can result in serious, rarely fatal, irregular heartbeats. Ask your doctor for more information and if you should stop taking any of your other medicines to reduce the risk of this side effect.

Caution is advised when using this medicine in the eldery because they may be more sensitive to the side effects of this medicine. This medicine should not be used in women or children.

Do not take this medicine if you have had an allergic reaction to it in the past or to any other ingredient that is found in it.

This medicine may cause dizziness or vision changes. Do not drive, operate machinery, or do anything else that could be dangerous until you know how you react to this medicine. Using this medicine alone, with other medicines, or with alcohol may lessen your ability to drive or to perform other potentially dangerous tasks. To minimize dizziness or lightheadedness, sit up or stand slowly when rising from a seated or lying position.

Your dose is based on your medical condition, response to therapy, and the other medicines you are taking. Do not exceed the recommended dose without checking with your doctor. Caution is advised when using this medicine in the elderly because they may be more sensitive to the side effects of this medicine. This medicine should not be used in women or children.

Possible side effects
Side effects that may occur while taking this medicine include headache, flushing, stomach upset, heartburn, nasal stuffiness, diarrhea, dizziness, or lightheadedness. Vision changes such as increased sensitivity to light, blurred vision, or impaired blue/green color discrimination may also occur. If these continue or are bothersome, check with your doctor or pharmacist.

Sexual activity may put extra strain on your heart, especially if you have heart problems, if you have heart problems and experience any serious side effects while having sex, stop having sex and tell your doctor immediately. These side effects include severe dizziness, fainting, chest pain, or nausea. In the unlikely event that you have a painful or prolonged erection (lasting more than 4 hours), stop using this medicine and seek immediate medical attention or permanent problems could occur.

An allergic reaction to this medicine is unlikely, but seek immediate medical attention if it occurs. Symptoms of an allergic reaction include rash, itching, unusual swelling, severe dizziness, or trouble breathing.

If you take too much
If overdose is suspected, contact your local poison control center or emergency room immediately. Symptoms of overdose may include severe dizziness, fainting, or prolonged erection.

Additional information
If your symptoms do not improve or if they become worse, check with your doctor. Do not share this medicine with others for whom it was not prescribed, since they may have a problem that is not effectively treated with this medicine, or they may have a condition that is complicated by this medicine.

Do not use this medicine for other health conditions. Keep this medicine out of the reach of children and pets. If using this medicine for an extended period of time, obtain refills before your supply runs out.

Drug interactions
Drug interactions can result in unwanted side effects or prevent a medicine from doing its job. Some medicines or medical conditions may interact with this medicine. Inform your doctor or pharmacist of all prescription and over-the-counter medicine that you are taking.