You can usually expect Cialis to start working quickly, often within 30 minutes — but of course, this is different for every man. That said, some men have reported the effects kicking in after just 15 minutes! The FDA has also approved tadalafil for treatment of both benign prostatic hypertrophy and erectile dysfunction where the two conditions co-exist. What to Know Before Taking Cialis If, after taking Cialis, Tadalafil, or any other ED drug, you find yourself with a painful erection for 4 hours or more, seek urgent medical advice. Tadalafil can be synthesized starting from D – tryptophan methyl ester and piperonal via a Pictet—Spengler reaction. The sound of a never-ending erection might sound fun to some people, but it can actually cause lasting damage to your penis. So, exactly when should you take Cialis, and how long does it take for the Tadalafil to kick in? · The Food and Drug Administration (FDA) has approved Cialis and Levitra to treat erectile dysfunction (ED) in males.*. ED is a condition in which you can’t get or keep . Cialis is a PDE5 inhibitor medication approved for use for erectile dysfunction (ED) and benign prostatic hyperplasia. Don’t take Cialis with nitrate class . tadalafil. erectile dysfunction (ED) benign prostatic hyperplasia, or BPH). Tadalafil (Cialis) is available both as brand-name and generic tablets. Common side .