Viagra, along with Levitra, Cialis, Staxyn, and Stendra, all belong to a family of medications known as PDE5 inhibitors. They are so called because they all temporarily disable an enzyme known as phosphodiesterase-5, which can interfere with blood flow to the penis, particularly in men whose vascular health is less than robust.
While all these drugs are similar in chemical structure, there is enough variation from one to another that you might find one work better for you than the others. Or you may find that they all produce the desired results, but one or more of them might cause you bothersome side effects. You will probably need to give each of these drugs a try to determine which is best for you. Viagra, Levitra, Staxyn, and Stendra all tend to become effective 30 to 60 minutes after they are taken, and all remain effective for four to six hours.
Cialis, in both it’s 10- and 20-milligram doses, is much longer lasting — up to 36 hours, earning it the nickname of the “weekend drug.” All of these medications have similar side effects, the most common of which are back pain, diarrhea, dizziness, flushing, headache, muscle ache, runny or stuffy nose, and upset stomach. Such side effects, if they occur at all, tend to be relatively mild and usually disappear upon continued use of the drug.