There are two different ways to take tadalafil, either daily or on an as needed basis. What should I do if I forget a dose? Patients who demonstrate hemodynamic instability on alpha-blocker therapy alone are at increased risk of symptomatic hypotension with concomitant use of PDE5 inhibitors. How should this medicine be used? Do not divide the 40 mg dose. Therefore, physicians should inform patients that substantial consumption of alcohol e. In such circumstances, nitrates should still only be administered under close medical supervision with appropriate hemodynamic monitoring.What is Cialis? 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). The dose may be increased to 20 mg or decreased to 5 mg, based on individual efficacy and tolerability. The maximum recommended dosing frequency is once per day in most patients. CIALIS for use as needed was shown to improve erectile function compared to placebo up to 36 hours following dosing. Side Effects. Headache, stomach upset, back pain, muscle pain, stuffy nose, flushing, or dizziness may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly. To.