Obesity Additionally, certain risk factors increase the risk of ED, such as smoking , lack of exercise, and drug or alcohol use. Erectile dysfunction medications require a prescription from a licensed provider. The mechanism of action for ED pills is simple: They inhibit the PDE5 enzyme which regulates the signals responsible for the smooth muscle tissue. Insurance: If you plan to use insurance, make sure the online provider accepts it. Some services offer a subscription option where they’ll send your medications every month at a discount.It belongs to the drug class known as PDE5 inhibitors. Tadalafil is its active ingredient and is available as a generic drug. The FDA has approved Cialis to treat ED, . AdComplete the Online Consultation with our Doctor. Personalize Your Needs. If Appropriate, Get a Prescription for ED from RexMD®. Free Shipping AvailableFree Shipping · Real Doctors · Discreet Packaging · Personalized PlanServices: Hair Loss, Erectile Dysfunction, Privacy Policy, Sexual Health and more. Cialis is a PDE5 inhibitor, a drug designed to treat erectile dysfunction (ED). It is a selective inhibitor of cyclic monosphosphate (cGMP)-specific phosphodiesterase type 5. Cialis .