Oral medicines for ED usually work well and cause few side effects. Although taking testosterone may help your ED, it is often unhelpful if your ED is caused by circulatory or nerve problems. Children 1 year of age and older weighing 45 kilograms kg or more—20 mg 3 times a day. Oral medicines can improve your response to sexual stimulation, but they do not trigger an automatic erection like injectable medicines do. Medicines that you take by mouth are called oral medicines. This medicine also works best when you take it an hour before sex on an empty stomach. An erection will begin within 8 to 10 minutes and may last 30 to 60 minutes. · This medicine usually begins to work for erectile dysfunction within 30 minutes after taking it. It continues to work for up to 4 hours, although its action is usually . Sildenafil and tadalafil are alike because they both can treat ED and PAH. However, tadalafil has a few distinctions from sildenafil. Tadalafil is the generic name for . Since , Viagra (sildenafil) has been used for treating erectile dysfunction (ED). It’s available by prescription for males ages 18 years and older. Side .