For many people with erectile dysfunction, medication is the solution of choice. Drugs such as sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra) are common pills men take to combat the diagnosis, and while short-term side effects are widely researched, the medications' long-term impact isn't always mentioned.

According to the Centers for Disease Control and Prevention (CDC), ED affects "around 30 million men in the U.S." (One study takes the number to 47.5 million.) The condition is often caused by several factors, such as stress, high blood pressure or a limited blood flow to the penis. Typically, the prescribed oral drugs belong to a group called phosphodiesterase type 5 inhibitors (PDE5), which block enzyme activity responsible for ED. The medications