Which Is More Effective? They are PDE5 inhibitors that allow for increased blood flow to the penis, leading to more frequent and harder erections. Reading about what’s good for you is even better. Cialis reaches its maximum effectiveness two hours after you take it. If this occurs, you should seek medical attention immediately. How long does it take for Cialis to peak?Cialis is approved by the FDA to treat erectile dysfunction (ED). Our medical team can prescribe Cialis 5mg, 10mg, and 20mg. The starting dose we generally recommend is 10mg. Tadalafil is the name for the active chemical ingredient in Cialis. PDE-5 inhibitors is the name of the group of medicines. Cialis is available as the generic drug tadalafil. A generic drug is an exact copy of the active drug in a brand-name medication and is considered just as safe and effective. Cialis can cost around $ to $ per month out of pocket, depending on the dosage you need. The first generic version of Cialis was released in October , and other manufacturers have released generic versions since then. This has increased market competition, driving prices down.