In 2019, the FDA approved esketamine, a derivative of ketamine, for treatment of severe depression when oral anti-depressants alone are unsuccessful.  Ketamine is sometimes thought to be a controversial treatment because despite being used for years in the hospital setting as an anesthetic and painkiller, it is also frequently abused as a recreational club drug.   Chief psychiatrist, John Krystal, MD at Yale Medicine believes esketamine, when used as part of a comprehensive treatment plan, could prove to be a revolutionary “game changer” for those struggling with severe anxiety and depression.