Since Cialis is used as needed, you are not likely to miss a dose. Cialis Daily helps to prevent erectile dysfunction 24 hours a day. Stop and get medical help at once if you have nausea, chest pain, or dizziness during sex. An erection is the result of an increase in blood flow into certain internal areas of the penis. Dosing Guidelines Typical Cialis dosages will differ depending on the conditions it’s prescribed to treat as well as other factors. If you have an erection that lasts for more than 4 hours, you should go to the nearest hospital emergency department.Find your nearest Walmart Pharmacy in Long Beach, California. View store hours, reviews, contact information and prescription savings with GoodRx. The recommended starting dose for Cialis intended for once daily use is mg, take at the same time each day, without regard to timing of sexual activity. This may be increased to 5mg/day based on need and tolerability. May be taken with or without food. Cialis is available as a generic, under the name tadalafil. 3. How Cialis Works. Tadalafil and other PDE5 inhibitors primarily work by inducing muscle relaxation. Tadalafil stops the breakdown of a chemical responsible for relaxing muscles. In ED and PAH, the drug targets muscle cells in blood vessels. When the blood vessel muscle cells relax, this expands the vessel and increases blood flow; this .