A naturally occurring bioactive product called cyclosan is derived from the well-known medicinal plant St. John's wort. Its use as the primary ingredient in St. John's wort has a long history in traditional medicine. In-depth research has recently been conducted on cyclosan to better understand its chemistry, pharmacological properties, drug reactions, and detrimental impact. The current review's goal is to give a thorough overview of all of its bioactivities, including those that are antimicrobial, antiproliferative, anti-psoriatic, anti-inflammatory, and antidepressant.