Special Warnings with Cialis:
Cialis can cause your blood pressure to drop suddenly to an unsafe level if it is taken with certain other medicines such as nitrates and alpha-blockers, and recreational drugs that contain nitrates called "poppers". A sudden drop in your blood pressure could cause you to become dizzy, faint, or have a heart attack or stroke.

Tell all your healthcare providers that you take Cialis. If you need emergency medical care for a heart problem, it will be important for your healthcare provider to know when you last took Cialis.