Cialis stimulates and increases the effects of nitric oxide on relaxing the blood vessels by blocking the Phosphodiesterase type 5 PDE5 enzyme. What Are the Symptoms of Erectile Dysfunction? Cialis is not immune to irritating or uncomfortable side effects. Erectile dysfunction can be caused by a variety of factors , including age, cardiovascular problems, diabetes, and other conditions that affect nerve function or blood flow. In some cases, ED can cause a strain on relationships and impact self-esteem.Introduction. If you’re looking at treatment options for erectile dysfunction (ED), you may want to learn more about Cialis and its cost. It’s a prescription drug used . Our medical team can prescribe it online and our pharmacy can mail it to you in 5mg, 10mg and 20mg dose. An even lower cost option for ED medicines is generic sildenafil 20mg . What is Tadalafil (Cialis)? Drug Facts. Common Brands Cialis. Drug Class PDE-5 inhibitor. Controlled Substance Classification Not a controlled medication. .