What should I do if I forget a dose? Your doctor can help you to choose the dosage that works for your current physical needs and past medical history. Without physical action to the penis, such as that occurring during sexual intercourse, tadalafil will not work to cause an erection. To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and site usage information with other information we have about you. Erectile dysfunction is a condition where the penis does not harden and expand when a man is sexually excited, or when he cannot keep an erection.Tadalafil (Cialis) does interact with some medications, such as heart and blood pressure medications, and taking them together could lead Some side effects .  · Cialis Descriptions Tadalafil is used to treat men who have erectile dysfunction (also called sexual impotence). Tadalafil belongs to a group of medicines . Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take tadalafil exactly as directed. Do not .