An important role of modern forensic and clinical toxicologists is to monitor the adverse events of novel psychoactive substances (NPS). This critical literature review analyzes and evaluates published case reports for NPS from January 2017 through December 2020. The primary objective of this study is to assist in the assessment and interpretation of these cases as well as provide references for confirmation methods. Chemistry, pharmacology, adverse events, and user profiles (e.g., polypharmacy) for NPS are provided including case history, clinical symptoms, autopsy findings, and analytical results.