Cialis was also investigated in combination with finasteride, another BPH medication, in another trial. Obesity Additionally, certain risk factors increase the risk of ED, such as smoking , lack of exercise, and drug or alcohol use. BPH occurs when the prostate and the surrounding tissues become enlarged. Take both tablets one after the other. The amount of medicine that you take depends on the strength of the medicine.Is taking Cialis 40 mg daily safe? Cialis: 7 Important Things to Know; View more FAQ.  · Adults—5 milligrams (mg) once a day, taken at the same time each day, without regard for the timing of sexual activity. Children—Use is not recommended. For treatment of pulmonary arterial hypertension: Adults—40 milligrams (mg) (two 20 mg tablets) taken once a day. Take both tablets at the same time each day. Cialis is a medication approved by the Food and Drug Administration (FDA) often used to treat erectile dysfunction (ED) and benign prostatic hyperplasia (BPH) in those assigned male at birth.