Levitra is a prescription medicine. It should be taken only with the guidance and supervision of a physician. It should not be taken if anyone is allergic to any of the ingredient in Levitra; if anyone has the heart problems like severe heart failure and unstable angina; if anyone has low blood pressure (BP); or if anyone has uncontrolled high BP. It should also be avoided if the person has retinitis pigmentosa, severe liver disorders, and severe kidney disorders that involve dialysis. If anyone had a heart attack or stroke in the past six months, he should avoid taking Levitra. It must be avoided taking Levitra if anyone already taking any medications (for example, capsules, ointments, patches, and tablets) with the combination of nitrates.