These medicines all work well for ED. This medicine also works best when you take it an hour before sex on an empty stomach. Popular ED medications found online include: Viagra sildenafil : As the first FDA-approved PDE5 inhibitor for ED, sildenafil is taken 30 minutes to four hours before sexual intercourse to help achieve and maintain an erection. The most common symptoms of erectile dysfunction include difficulty achieving or maintaining an erection and reduced sexual desire. A phone or video consultation is sometimes required for legal purposes. You can take it in a small dose daily or in a larger dose as needed.Tadalafil (Cialis). This medication is taken with or without food an hour before sex. It works for up to 36 hours. You can take it in a small dose daily or in a larger . We have good news for you: generic Cialis, used to treat erectile dysfunction (ED)and enlarged prostates, just hit pharmacies. Prices for the generic, .