Population data estimates that around 200 million individuals use cannabis worldwide. Being one of the most widely used recreational drugs, it is imperative to understand the effects of cannabis. While cannabis has been implicated in the development, worsening, and treatment of psychosis and cognitive dysfunction, this recent review explored the contributions of THC and CBD such effects. Frequent and high THC cannabis was associated with a higher risk of psychosis, especially in individuals with genetic vulnerabilities. In contrast, some studies have found that CBD has antipsychotic effects. Not only may it prevent, reverse, or reduce the effects of THC, but CBD is also being tested as a treatment for multiple psychiatric conditions. These effects may be dependant on age and disease progression.