Do not break or split a Cialis tablet. We prescribe 3 different doses: 5mg, 10mg and 20mg. Potential Side Effects and Interactions While Cialis is generally safe, like all medications, it can have side effects. Use the medicine exactly as directed. No more queuing up at the pharmacy or scheduling visits; with just a few clicks, your medication can be on its way to your doorstep.Published on October 18, warning. This article is no longer being updated and some information may not be current. Visit the GoodRx Healthhomepage for our latest articles. We have good news for you: generic Cialis, used to treat erectile dysfunction (ED)and enlarged prostates, just hit pharmacies. Cialis form and strengths ( mg, 5 mg, 10 mg, 20 mg) Cialis comes as oral tablets that are available in four strengths: milligrams (mg), 5 mg, 10 mg, and 20 mg. Recommended dosage for Cialis. What is Tadalafil (Cialis)? Drug Facts. Common Brands Cialis. Drug Class PDE-5 inhibitor. Controlled Substance Classification Not a controlled medication. Generic Status No lower-cost generic available. Availability Prescription only. How Tadalafil (Cialis) works. Tadalafil (Cialis) is a phosphodiesterase-5 enzyme (PDE-5) inhibitor.