Which Lasts Longer? Viagra Choosing the right ED pill can be intimidating. Those with pre-existing conditions should always consult a healthcare provider before taking new medications or supplements. National Library of Medicine. Other conditions that may disqualify you from an ED prescription include a history of stroke, kidney or liver disease, cancer, diabetes, or a bleeding disorder. They have the same benefits and risks as their brand-name counterparts.Cialis and Viagra are both pills for treating erectile dysfunction. They are PDE5 inhibitors that allow for increased blood flow to the penis, leading to more frequent and harder . Yes. 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 . In addition to Viagra, REX MD also offers brand-name Cialis and generic Cialis (tadalafil). Both Viagra and sildenafil are available in mg, mg, and mg doses. REX MD .