You should only be treated with one of these products at a time. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Side effects Side effects of oral ED medicines are often mild. Tell your doctor if tadalafil is not working well or if you are experiencing side effects. It works to treat erectile dysfunction by increasing blood flow to the penis during sexual stimulation. Often, these are prescribed for chest pain called angina. Tadalafil is sometimes taken as needed, usually at least 30 minutes before sexual activity and not more often than once every 24 hours.CIALIS for Use as Needed. Creatinine clearance 30 to 50 mL/min: A starting dose of 5 mg not more than once per day is recommended, and the maximum dose is 10 mg not more than once in every 48 hours. Creatinine clearance less than 30 mL/min or on hemodialysis: The maximum dose is 5 mg not more than once in every 72 hours [see . Tadalafil, the generic version of Cialis is available for about $9 for 30 tablets of the 5 mg strength. Does cialis have a generic? expand_more. Yes, Cialis is available as a generic medication called tadalafil. Generic medications are just as effective as the brand. Tadalafil 10 mg is available for about $10 for 10 tablets with GoodRx. Tadalafil (Cialis) is available both as brand-name and generic tablets. Common side effects of this medication include headache and indigestion. Tadalafil .