They’re often the first line of treatment for trouble getting or keeping an erection, called erectile dysfunction ED. It lasts 4 to 5 hours, or longer if you have mild to moderate ED. How oral medicines differ Each oral medicine for ED has a slightly different chemical makeup. Common ones include: Flushing of the skin. These are commonly prescribed for an enlarged prostate or male pattern baldness. Sildenafil Viagra. First and foremost, be sure that whichever online pharmacy you choose is legitimate, safe, and secure.Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in men. It is also used to treat pulmonary arterial hypertension, a serious heart and lung . Sildenafil (Viagra). This medicine works best when you take it on an empty stomach an hour before sex. The body takes longer to absorb it after a high-fat meal or .