Do not take Levitra if you are also using a nitrate drug for chest pain or heart problems. This includes nitroglycerin (Nitrostat, Nitrolingual, Nitro-Dur, Nitro-Bid, and others), isosorbide dinitrate (Dilatrate-SR, Isordil, Sorbitrate), and isosorbide mononitrate (Imdur, ISMO, Monoket). Nitrates are also found in some recreational drugs such as amyl nitrate or nitrite ("poppers"). Taking Levitra with a nitrate medicine can cause a serious decrease in blood pressure, leading to fainting, stroke, or heart attack. If you have any of these other conditions, you may need to adjust the dose of Levitra or have special tests: heart disease or heart rhythm problems; a recent history (in the past 6 months) of a heart attack, angina (chest pain), or congestive heart failure; a recent history of stroke or blood clots; a personal or family history of "Long QT syndrome"; high or low blood pressure; liver disease; kidney disease (or if you are on dialysis); a blood cell disorder such as sickle cell anemia, multiple myeloma, or leukemia; a bleeding disorder such as hemophilia; a stomach ulcer; retinitis pigmentosa (an inherited condition of the eye); 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. Levitra 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 Levitra, most of whom also had heart disease, diabetes, high blood pressure, high cholesterol, or certain pre-existing eye problems, and in those who smoke or are over 50 years old. It is not clear whether Levitra is the actual cause of vision loss.Stop using Levitra and get emergency medical help if you have sudden vision loss. FDA pregnancy category B: Although Levitra is not for use in women, this medication is not expected to be harmful to an unborn baby. Although Levitra is not for use in women, it is not known if vardenafil passes into breast milk or if it could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.