You’ll soon start receiving the latest Mayo Clinic health information you requested in your inbox. If you are taking tadalafil on a regular schedule, take it at around the same time every day. If you are taking tadalafil for erectile dysfunction, your doctor will probably start you on an average dose of tadalafil and increase or decrease your dose depending on your response to the medication. This combination of factors works to resolve issues with erectile dysfunction that some guys have. Instead of taking many pills per day, Tadalafil can be part of your daily routine.1. What is Cialis used to treat? Cialis is approved for the treatment of men who experience difficulty having and maintaining an erection (impotence). 2. How does Cialis work? . Cialis and generic tadalafil are available with a prescription only. There is no OTC version, though there have been efforts in recent years to develop a . Take tadalafil exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor. If you are taking tadalafil to treat PAH or BPH, follow your .