Common ones include: Flushing of the skin. Avanafil Stendra. Click here for an email preview. Sildenafil belongs to a group of medicines called phosphodiesterase 5 PDE5 inhibitors. Your doctor or other health care professional can recommend one for you based on these factors, other health conditions you have and any other medicines you take.CHOOSE BRAND-NAME VIAGRA. The original little blue pill prescribed by doctors for over 20 years. Clinically proven to treat men with erectile dysfunction (ED) Ongoing commitment to product quality and safety monitoring. In combination with sexual stimulation, sildenafil works by increasing blood flow to the penis to help a man get and keep an drug does not protect against sexually transmitted. 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.