We considered cost, medications available, and whether generic versions were offered to help reduce costs. However, some states require a live video consultation. It can influence how much Cialis is in the bloodstream and, therefore, the efficacy of the medication. This allows the smooth muscles in the penis to relax and fill with blood. People taking nitrates like nitroglycerin Nitrostat or isosorbide mononitrate Imdur should not take PDE5 inhibitors, as doing so could result in a dangerous drop in blood pressure. Both options require valid medical documentation, but some online services only require a health questionnaire to be filled out and reviewed for approval—meaning no face-to-face video interaction is needed.Published on October 18, warning. This article is no longer being updated and some information may not be current. Visit the GoodRx Healthhomepage for our latest articles. . What is Tadalafil (Cialis)? Drug Facts. Common Brands Cialis. Drug Class PDE-5 inhibitor. Controlled Substance Classification Not a controlled medication. . Products. Cialis. What is Cialis. Cialis is a PDE5 inhibitor, a drug designed to treat erectile dysfunction (ED). It is a selective inhibitor of cyclic monosphosphate (cGMP)-specific .