This medicine works best when you take it on an empty stomach an hour before sex. If you are a Mayo Clinic patient, this could include protected health information. You have to watch out for any side effects. Are you anxious, depressed or under stress? Have you had any other sexual problems? Medicines that you take by mouth are called oral medicines.The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 . If you sense your doctor is uncomfortable talking about ED, ask for a referral to a urologist—a specialist trained to treat conditions related to the urinary tract and male . Here’s our process. How we vet brands and products Erectile dysfunction (ED) is the medical term for trouble getting or maintaining an erection that is satisfying for sexual .