If you are taking tadalafil to treat erectile dysfunction, you should know that it does not cure erectile dysfunction or increase sexual desire. If you need emergency medical care for a heart problem, it will be important for your health care provider to know when you last took Cialis. Viagra is always taken as needed, usually an hour before having sex. Viagra can be taken as long as four hours or as little as 30 minutes before sex. Tadalafil is sometimes taken as needed, usually at least 30 minutes before sexual activity and not more often than once every 24 hours.Dosage. The dose of Cialis you need will depend on whether you’re taking it daily or as needed. Daily doses are often between and 5 milligrams (mg). The as-needed dose is usually 10 mg but can range from 5–20 mg. The typicaldose of Viagra is 50 mg. However, the dosage can range from 25– mg. Dosage range: mg to 5 mg. Frequency: once daily, regardless of the timing of sexual activity. Cialis’s recommended dosage when it’s taken as needed for ED is as follows. Dosage range: 5 mg to 20 mg. Frequency: one dose at least 30 minutes before sexual activity, with a maximum of one dose per day*. 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 .