Each erectile dysfunction medication (including Cialis, Viagra, and Levitra) has subtle variations in its onset of action and duration of action. Similarly, each medication will have a different set of side effects. The most common side effects are headache, stuffy nose, flushing of the face and rarely dizziness or lightheadedness.
More serious side effects of these medications (called the "phosphodiesterase inhibitors") have also been reported, including the association with...

