Levitra is a phosphodiesterase inhibitor

Levitra is a phosphodiesterase inhibitor. It works by helping to increase blood flow into the penis during sexual stimulation. This helps you to achieve and maintain an erection.
Do NOT use Levitra if:
* you are allergic to any ingredient in Levitra
* you have been advised by your doctor to avoid sexual activity because of heart problems
* you have certain heart problems (eg, unstable angina, severe heart failure), low blood pressure, or uncontrolled high blood pressure
* you have certain hereditary degenerative eye problems (eg, retinitis pigmentosa)
* you have severe liver problems or severe kidney problems that require dialysis
* you have had a heart attack, stroke, or life-threatening irregular heartbeat within the past 6 months
* you are taking nitrates (eg, isosorbide, nitroglycerin) in any form (eg, tablet, capsule, patch, ointment), nitroprusside, or certain antiarrhythmics (eg, quinidine, amiodarone)
* you use certain recreational drugs called "poppers" (eg, amyl nitrate, butyl nitrate)
Contact your doctor or health care provider right away if any of these apply to you.
Before using Levitra :
Some medical conditions may interact with Levitra . Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:
* 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, Peyronie disease, cavernosal fibrosis), blood problems (eg, sickle cell anemia, leukemia, multiple myeloma), or any other condition that may increase the risk of a prolonged erection (priapism)
* if you have a history of certain eye problems (eg, sudden vision loss, optic neuropathy, macular degeneration)
* if you have a history of liver or kidney problems, high or low blood pressure, ulcers, bleeding problems, blood vessel problems, or heart problems (eg, heart failure, aortic stenosis, angina)
* if you have a history of heart attack, stroke, a certain type of irregular heartbeat (long QT syndrome), or a family history of long QT syndrome
Some MEDICINES MAY INTERACT with Levitra . 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
* Certain antiarrhythmics (eg, quinidine, amiodarone) because the risk of irregular heartbeat may be increased
* Azole antifungals (eg, itraconazole), HIV protease inhibitors (eg, ritonavir), macrolide antibiotics (eg, erythromycin), or telithromycin because they may increase the risk of Levitra 's side effects
* Rifampin because it may decrease Levitra 's effectiveness
This may not be a complete list of all interactions that may occur. Ask your health care provider if Levitra 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.