Retho-Cialis is the brand name of the active substance Tadalafil and is a medication that is used to treat erectile dysfunction (ED). The product is much better known simply as Cialis but both Cialis and Retho-Cialis are actually the same product since they both offer the same active ingredient known as Tadalafil. There are a number of other different brand names for Tadalafil such as Tadacip, Adcirca and many others. All of these names including Retho-Cialis are considered generic versions of Cialis.