The prevalence of cannabis use has been increasing among both adolescents and adults worldwide. New trends in cannabis legalization and enhanced social media marketing have led to the availability of multiple high-potency cannabis products with hundreds of new and powerful delivery systems. Over the last decade, there have been drastic changes in cannabis formulations, potency, routes of consumption, and device technology, with increased complexity and sophistication among growers, suppliers, and consumers. Patterns of cannabis use among patients can have important clinical implications, including acute neurocognitive effects, chronic multiorgan toxicity, psychiatric, behavioral, social, and economic impact. However, assessment of medical or surgical patients who use cannabis either recreationally or problematically has become challenging for the clinician due to the changing patterns of cannabis consumption. This review provides information on the clinical evaluation of patients who use cannabis in a problematic fashion, with the focus on tetrahydrocannabinol. It provides the clinician with knowledge regarding cannabis terminology, sources, pharmacology, routes of administration, formulations, dosing, and toxicities. Using these components, an assessment approach for diagnosing cannabis use disorder is synthesized at the conclusion of the article.