It might be a while before MED is available at your local pharmacy. Medicines that you take by mouth are called oral medicines. Medicines that block an enzyme called CYP3A4. You can take it in a small dose daily or in a larger dose as needed. These are commonly prescribed for an enlarged prostate or male pattern baldness.The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 . Viagra works by helping the blood vessels in your penis relax to allow more blood flow. Since then, the FDA has approved other types of medications to treat ED, but they’re all . Another type of ED treatment you can get without a prescription is a vacuum device. Some call it a penis pump. These devices can be effective; however, it’s safer to use one .