Of course, buying ED pills online still comes with a risk. The mechanism of action for ED pills is simple: They inhibit the PDE5 enzyme which regulates the signals responsible for the smooth muscle tissue. Yes, ED pills can cause side effects. An erection results from an increase in blood flow to the penis. Post navigation. Oral prescription medications are one popular route. It’s best to check your chosen provider’s site for more information.In many cases, erectile dysfunction is caused by something physical. Common causes include: Heart disease. Clogged blood vessels (atherosclerosis) High . Get the facts on five over-the-counter ED pills. Learn how options like DHEA and yohimbe can help treat erectile dysfunction. Learn about warnings and more. You have many different options for treating erectile dysfunction (ED). A few common medications include tadalafil, testosterone, avanafil, and vardenafil. To get .