An inherited eye disease that affects the retina. But, keep in mind that ED might signal an underlying medical problem, like high blood pressure, heart disease, diabetes, low testosterone, or sleep apnea. It might be a while before MED is available at your local pharmacy. When choosing one, tell your doctor or other health care professional what your preferences are, such as cost, ease of use, how long the drug’s effects last and side effects. Clinical trials for MED found minimal side effects. They’re often the first line of treatment for trouble getting or keeping an erection, called erectile dysfunction ED. Medicines that you take by mouth are called oral medicines.The Walmart $4 Prescriptions program requires no membership, no fee, and no insurance, and offers patients discounted medications in day and day supplies. Often referred . Viagra is usually taken only when needed, 30 minutes to 1 hour before sexual activity. You may take it up to 4 hours before sexual activity. Do not take Viagra more than once per . Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that .