Yes, ED pills can cause side effects. Your clinician will consider your health history and personal preferences when prescribing treatment. Your prescribing clinician may consider how often you plan to use the medication. That’s not to say there aren’t just as many illegitimate sites. This increase in blood flow results in a firmer, longer-lasting erection. Read our editorial process. However, others work on a cash-pay basis and don’t partner with insurance companies.Cialis (tadalafil) is a prescription medication for those with erectile dysfunction. Many providers sell Cialis online — learn about the safest and most discreet providers here. Drug Facts Common Brands Cialis Drug Class PDE-5 inhibitor Controlled Substance Classification Not a controlled medication Generic Status No lower-cost generic available Availability Prescription only How Tadalafil (Cialis) works Tadalafil (Cialis) is a phosphodiesterase-5 enzyme (PDE-5) inhibitor. It works by blocking PDEMissing: amazon. Amazon Pharmacy: Cialis (Brand for Tadalafil, Oral Tablet).us. Account Returns& Orders. Cart. Transfer your prescription for Cialis (Brand for Tadalafil, Oral Tablet) on Amazon Pharmacy. FREE SHIPPING for Prime members.