If you receive medical care for heart problems, tell your caregivers when you last took vardenafil. The maximum recommended dosage for Levitra is 20mg per day. This medicine does not prevent the spread of sexually transmitted diseases such as human immunodeficiency virus HIV. Do not use any other medicine to treat impotence unless your doctor tells you to. Sildenafil Otherwise known as generic Viagra, sildenafil is another PDE5 inhibitor that treats erectile dysfunction.Levitra takes about 30 minutes to start working and the effects last a little longer than Viagra, about 5 hours. Staxyn dissolves in your mouth. It contains the same active ingredient as Levitra. Hearing loss or ringing in ears. Heart attack—pain or tightness in the chest, shoulders, arms, or jaw, nausea, shortness of breath, cold or clammy skin, feeling faint or lightheaded. Low blood pressure—dizziness, feeling faint or lightheaded, .  · General Dose Information. For most patients, the recommended starting dose of LEVITRA is 10 mg, taken orally, as needed, approximately 60 minutes before sexual activity. The dose may be increased to a maximum recommended dose of 20 mg or decreased to 5 mg based on efficacy and side effects. The maximum recommended .