Levitra (vardenafil) is a commonly prescribed anti-impotence agent specially intended for men who have trouble achieving an erection that would be hard enough to have sex. Take this medicine 60 minutes before having sex to provide for its maximum efficiency. You can expect 4 hours of Levitra effects from that point. You can continue with the treatment even though you may get any of the following mild side effects, such as flushing, flu-like symptoms, stuffy or runny nose, headache, upset stomach, and heartburn. If you get serious side effects, such as sudden vision loss, penis erection that is painful or lasts 4 hours or longer, swelling in your hands, sweating, shortness of breath, seizure, chest pain, irregular heartbeat, sudden hearing loss, ringing in your ears, nausea, general ill feeling, or feeling light-headed, talk to your health care provider as soon as possible. Your doctor is supposed to know your full medical history before prescribing Levitra, especially about such medical conditions as blood clots or stroke, liver or kidney disease, inherited eye problems, angina, congestive heart failure, stomach ulcer, high or low blood pressure, bleeding disorder, blood cell disorder, heart rhythm problems, or heart attack.