Comparison with actions of other PDE5 inhibitors[ edit ] Sildenafil and vardenafil inhibit PDE6, an enzyme found in the eye, more than tadalafil. The FDA has also approved tadalafil for treatment of both benign prostatic hypertrophy and erectile dysfunction where the two conditions co-exist. One advantage Cialis has over Viagra and Levitra is its Symptoms may include sudden urges to urinate urgency , difficulty in starting urination hesitancy , a weak urine stream, and more frequent urination — especially at night. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail. This medicine comes with a patient information leaflet. Follow your doctor’s orders or the directions on the label.Official answer. The maximum recommended dose of Cialis is 20mg daily. Increasing the dose to 40mg might just increase the intensity of side effects and may not actually deal with the erectile dysfunction problem. If 20mg dose is not working you might want to look for an another medicine. Sometimes even a medicine in the same class . Cialis (tadalafil), for instance, is one of the most popular brand-name ED medications, and it is manufactured by Eli Lilly. Cialis can cost around $ to $ per month out of pocket, depending on the dosage you need. The first generic version of Cialis was released in October , and other manufacturers have released generic versions .  · What is Cialis? Cialis is a brand-name prescription medication. It’s FDA-approved to treat the following in males:* erectile dysfunction (ED), a condition in which you can’t get or keep an.