Viagra, Cialis and Levitra work in very similar ways, but are uniquely different with regard to specific ingredients, exact absorption time, side effects and length of effectiveness. Each patient may respond differently to the three drugs, each of which can be administered at different doses.

The short answer is that there is no simple answer as to which drug will work best for you. The best course of action is to research each of the three FDA-approved ED drugs mentioned above and then consult with your doctor.

Because Viagra was the first FDA-approved drug in 1998, it still controls the ED market with about 60 percent of overall sales. However, Cialis has made consistent annual gains on Viagra since it was introduced in 2003. Cialis now earns about 30 percent of the market share, while Levitra has stayed consistent with about 10 percent of the market.  

For more information, see the informative comparison chart that Viagra.MD has prepared for ED medications. It compares Viagra, Cialis and Levitra in many different areas.