Find drug information for Tadalafil on CVS.com, including related drug classes, side effects, dosage, and answers to frequently asked questions. The recommended starting dose of CIALIS for use as needed in most patients is 10 mg, taken prior to anticipated sexual activity. The dose may be increased to 20 mg or decreased to 5 mg, based on individual efficacy and tolerability. If your doctor prescribes tadalafil as needed for ED, your starting dose will likely be 10 mg. Typically, you’ll take this right before sexual activity. If this dose isn’t working for you, your. The recommended starting dose of CIALIS for use as needed in most patients is 10 mg, taken prior to anticipated sexual activity. The dose may be increased to 20 mg or decreased to 5 mg, based on individual efficacy and tolerability. CIALIS for Use as Needed — For patients taking concomitant potent inhibitors of CYP3A4, such as ketoconazole or ritonavir, the maximum recommended dose of CIALIS is 10 mg, not to exceed once. In combination with sexual stimulation, tadalafil works by increasing blood flow to the penis to help a man get and keep an erection. Tadalafil is also used to treat the symptoms of an enlarged prostate (benign prostatic hyperplasia-BPH). For erectile dysfunction, Cialis can be taken occasionally as needed (10 mg, adjusted to 5 mg or 20 mg) or daily (2.5 mg, adjusted to 5 mg). But it should not be taken more than once per day. Cialis relaxes muscles of the blood vessels and increases blood flow to particular areas of the body. Cialis is used to treat erectile dysfunction (impotence) and symptoms of benign prostatic hypertrophy (enlarged prostate). Adults—10 milligrams (mg) as a single dose, no more than once a day, taken 30 minutes before you think sexual activity may occur. Your doctor may adjust your dose as needed. Common Uses: It is used to treat erectile dysfunction (ED).It is used to treat the signs of an enlarged prostate.It may be given to you for other reasons. Talk with the doctor. WHAT DO I NEED TO TELL MY DOCTOR BEFORE I TAKE THIS DRUG?.