While each PDE5 inhibitor differs slightly, they’re very similar in treating erectile dysfunction. Those with pre-existing conditions should always consult a healthcare provider before taking new medications or supplements. Your primary care doctor should always know what medications you’re taking, including ED pills prescribed by another provider. Never purchase ED medications from a site or service that doesn’t require a prescription and medical documentation. However, some states require a live video consultation. Finding an online ED provider can feel overwhelming. An erection results from an increase in blood flow to the penis.How do ED medications work? Viagra, Cialis, Levitra, and Stendra are all in a class of medications called phosphodiesterase type 5 (PDE5) inhibitors. These drugs . Cialis (tadalafil) is an expensive drug used to treat erection problems in men. It may also be used to treat the enlargement of the prostate gland. This drug is slightly more popular .