Some services offer a subscription option where they’ll send your medications every month at a discount. It’s available in 50 mg, mg, and mg tablets. These medicines all work well for ED. Tadalafil Cialis. It might work longer if you have mild to moderate erectile dysfunction. Never purchase ED medications from a site or service that doesn’t require a prescription and medical documentation. · What is Teva sildenafil? Sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor. This means that it helps block the PDE5 enzyme that affects certain muscles in . Still, if your doctor says it’s okay for you to use and you end up paying out-of-pocket, you can still get the generic for a lot less than Viagra. According to price . Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes .