The decision of availability is completely up to the company marketing the product. Journal of research in pharmacy practice, 5 3 , — Our team, across some countries, is dedicated to transforming the practice of medicine by working to turn the impossible into the possible. This is a serious condition that requires immediate medical attention. OTC Cialis substitutes come with health risks. Physicians should discuss with patients the potential for CIALIS to augment the blood-pressure-lowering effect of alpha-blockers and antihypertensive medications. Some over-the-counter ED drugs come with serious health risks.Tadalafil (Cialis) is a phosphodiesterase-5 enzyme (PDE-5) inhibitor. It works by blocking PDE This is a protein in your body that breaks down the molecules that normally cause an erection. When it blocks PDE-5, tadalafil (Cialis) helps an erection . Updated 09/22/ You’re with your partner, the lights are low and you’ve pressed play on your “Sexy Time” playlist. There’s just one thing missing: an erection. This is where Cialis® comes in. Cialis, the brand name for tadalafil, is FDA-approved for the . not available over-the-counter (OTC) Was this helpful? How does Cialis work? Cialis works by increasing blood flow to the penis to help a person get and maintain an erection. It also blocks.