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. Avanafil Stendra. That’s not to say there aren’t just as many illegitimate sites. It’s available in 50 mg, mg, and mg tablets. Please expect up to 4 to 6 weeks for reimbursement. Side effects Side effects of oral ED medicines are often mild.Extra 15% off $30 sitewide with code SAVE15; Clip your mystery deal! BOGO 50% off select Walgreens health & wellness. Oral medicines for ED usually work well and cause few side effects. The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. Can I buy generic Viagra over the counter or do I need a prescription? In the U.S. and most other countries, generic Viagra is only available with a prescription.