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. Cialis: Is one right for you? If you are taking tadalafil for erectile dysfunction on a regular schedule, take the missed dose as soon as you remember it. You can take Viagra daily, but because the medication stays in your system for four to six hours, it will not be effective all day. Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medicine. Ask your doctor if you are not sure whether any of your medications contain nitrates.Tadalafil – STADA T20 – 20 Milligramm. Tadalafil, sold under the brand name Cialis among others, is a medication used to treat erectile dysfunction, benign prostatic hyperplasia, and pulmonary arterial hypertension. It is taken by mouth. Onset is typically within half an hour and the duration is up to 36 hours. Common side effects include headache, muscle pain, . stockcam / Getty Images. What is generic Cialis? Generic Cialis is called tadalafil, which is the active ingredient in Cialis. Cialis is Food and Drug Administration (FDA) approved to. Cialis contains the active drug ingredient tadalafil and belongs to a group of medications called phosphodiesterase 5 (PDE5) inhibitors. For ED, Cialis relaxes the blood vessels .