Its effects might last longer if you have mild to moderate ED. Sexual activity is not a major contributor to the risk of a heart attack. Oral medicines for ED usually work well and cause few side effects. Vardenafil Levitra is more selective than sildenafil and tadalafil Cialis to PDE5, which again means a lower dose is needed with potentially less side effects. Concerning the orgasmic response, testosterone modulates the integrity of genital sensory receptors. These include a heart attack, stroke or a serious heart rhythm disorder in the past six months.Viagra takes around 30 minutes to become effective and lasts about 4 hours. Cialis lasts much longer — up to 36 hours in some cases. Stendra can start doing its thing in as little . What to consider. Cost. Overdose. Ask your doctor. Q&A. Drug Images. What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that . Sildenafil (Viagra) has a half-life of 4 hours and vardenafil (Levitra) has a half-life of hours while tadalafil (Cialis) has a half-life of hours. This means that vardenafil .