You may attempt sexual activity at any time between doses. Sildenafil, the active ingredient in Viagra, was originally developed in the early s to treat cardiovascular disease. This medicine is available only with your doctor’s prescription. Tadalafil is also used in both men and women to treat the symptoms of pulmonary arterial hypertension to improve your ability to exercise. Cialis was also investigated in combination with finasteride, another BPH medication, in another trial. Murphy says Cialis can be taken whenever you want and allows for more spontaneous sexual activity. Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medicine.As of September , generic daily 5 mg tadalafil can cost around $8 per dose, and higher doses of generic tadalafil — 10 mg and 20 mg — can start around $44 per pill. Pros. It can be taken. 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 . Cialis; Descriptions. Tadalafil is used to treat men who have erectile dysfunction (also called sexual impotence). Tadalafil belongs to a group of medicines called .