Viagra, Cialis, and Levitra are all part of a class of medications called PDE5 inhibitors. Essentially these drugs help increase blood flow to the penis to produce longer lasting, firmer erections. Sexual stimulation is required for these medications to work. Viagra, Cialis, and Levitra have similar common side effect profiles with some differences. They include headache, facial flushing, upset stomach, vision changes, and drop in blood pressure to name a few. Some men don´t experience any side effects. If the medical providers at NuMale determine these medications are safe for you, the only way to really know which treatment will produce the least side effects is to try it.