Tadalafil has been extensively studied for ED. The four main medicines taken by mouth for erectile dysfunction are: Avanafil Stendra. Tadalafil works on the PDE5 enzyme in the lungs to relax the blood vessels. Meds arrive in the mail in just two days. Alternatively, Cialis may be prescribed as an as-needed treatment for ED, to be taken before sexual activity.Cialis is used to treat erectile dysfunction (impotence) and symptoms of benign prostatic hypertrophy (enlarged prostate). Another brand of tadalafil is Adcirca, which is used to treat pulmonary arterial hypertension . Cialis (tadalafil) is an orally administered prescription medication used for erectile dysfunction (ED) and pulmonary arterial hypertension (PAH) to reduce the symptoms of an enlarged prostate. This article will explain how it works alongside other pertinent information regarding its consumption. 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.