Research into Cannabis induced psychosis and marijuana's effect on pre-existing mental disorders has been underway for several decades. However, many of these findings have surfaced in the U.S. over the last 15 years. Most of the information includes endogenous cannabinoid receptors in the brain, facts recently discovered, and more scientific evidence is needed to fully understand their role in Cannabis induced psychosis. Because cannabinoid receptors are neuromodulators, neurotransmitters are involved and how these are affected has yet to be discovered. Based on current understanding of neurotransmitters, the central nervous system, and mental disorders, this narrative review explores possible mechanisms of Cannabis induced mental disorders from a toxicological, pharmacological, and psychological perspective. This review also discusses the myth that no long-term ailments or illnesses arise from Cannabis use. It also illustrates why it is important to consider the potential consequences of legalizing Cannabis due to costly impacts on society with respect to public health and safety. Additionally, the author shares an experience observing an individual suffering from a mental disorder whose increased marijuana use led to more frequent, and dangerous, manic episodes.