You can buy it from a store-based pharmacy or reputable online pharmacy with a prescription. A small number of patients taking Cialis also reported abnormal vision. Your healthcare provider may prescribe Cialis for daily use at a daily dosage of 2. Taking more than 1 dose every 24 hours can cause heart issues and other problems. Tell your doctor if any of these symptoms are severe or do not go away: headache. By inhibiting the effects of PDE5, medications such as Cialis relax and expand the blood vessels near the penis and increase blood flow, allowing for easier, more reliable erections. If you are already taking medication to treat BPH, your doctor may tell you to stop taking your other medication at least one day before starting treatment with tadalafil.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*. Tadalafil (Cialis) is used to treat erectile dysfunction (ED, impotence; inability to get or keep an erection), and the symptoms of benign prostatic hyperplasia (BPH; an enlarged prostate) which include difficulty urinating (hesitation, dribbling, weak stream, and incomplete bladder emptying), painful urination, and urinary frequency and urgency in adult men. For a complete listing see Dosage Forms, Composition and Packaging section. INDICATIONS AND CLINICAL USE CIALIS (tadalafil) is indicated for the treatment of .