Before using
Do not take this medicine if you are also taking or using any form of nitroglycerin, other nitrates such as 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 before taking this medicine. Do not take this medicine if you are taking an alpha-blocker medicine such as doxazosin, prazosin, or terazosin. If you are taking any of these medicines, contact your doctor or pharmacist before taking vardenafil.

Additional monitoring of your dose or condition may be needed if you are taking other medicine for impotence; certain antifungal medicines such as itraconazole or ketoconazole; rifamycins such as rifampin; cimetidine; erythromycin; medicine for high blood pressure; medicine for abnormal heartbeats such as quinidine, procainamide, amiodarone, or sotalol; hiv protease inhibitors such as ritonavir or indinavir, or st. John's wort.

Additional monitoring of your dose or condition may be needed if you are taking other medicines which may change the way the heart beats such as phenothiazines, tricyclic antidepressants, quinolone antibiotics, and others. Do not start or stop any medicine without doctor or pharmacist approval. Inform your doctor or any other medical conditions including penis problems; history of painful or prolonged erection; sickle cell anemia; blood system cancers such as leukemia or myeloma; eye diseases, especially retina diseases such as retinitis pigmentosa, kidney or liver disease, bleeding disorders, active stomach ulcers, heart problems of any kind including arrhythmias, stroke, very high or low blood pressure, or allergies.

Do not take this medicine if you have been told by your healthcare provider to not have sexual activity because of certain health problems, especially heart problems. Contact your doctor or pharmacist if you have any questions or concerns about taking this medicine.

Directions
Follow the directions for using this medicine provided by your doctor. This medicine comes with a patient information leaflet. Read it carefully. Ask your doctor, nurse, or pharmacist any questions that you may have about this medicine. Take this medicine by mouth as needed 1 hour before sexual activity or as directed by your doctor.

Do not take this medicine more often than once daily as needed. If you are taking certain other medicines you may only be able to take this medicine one time every three days. Contact your doctor or pharmacist for more information. This medicine may be taken on an empty stomach or with food. However, taking this medicine with a high-fat meal may reduce the amount of medicine that your body absorbs.

Store this medicine at room temperature 77 degrees F (25 degrees C) in a tightly-closed container, away from heat 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 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. 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.

Before you begin taking any new medicine, either prescription or over-the-counter, check with your doctor or pharmacist. 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 or nausea, heartburn, stuffy or runny nose, diarrhea, dizziness, or lightheadedness. Rarely 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. Contact your doctor immediately if you experience fast, slow, or irregular heartbeats.

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 even 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 notice other effects not listed above, contact your doctor, nurse, or pharmacist.

If you take too much
If overdose is suspected, contact your local poison control center or emergency room immediately. Symptoms of overdose may include back pain, muscle pain, and abnormal vision.

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.