Marijuana Use and Its Impact on Outpatient Anesthesia

Cannabis is one of the most common psychoactive substances used worldwide, and its use is increasing. Modern products vary widely in tetrahydrocannabinol (THC) concentrations and usage routes, creating challenges for anesthesia providers. This review summarizes current evidence on the pharmacology, pharmacokinetics, physiologic effects, and perioperative considerations of cannabis to help guide safe anesthetic management of cannabis-using patients. Cannabis contains over 100 phytocannabinoids, chiefly psychoactive Δ9-THC and nonpsychoactive cannabidiol (CBD), which act on cannabinoid type-1 (CB1) and type-2 (CB2) receptors. Chronic use downregulates CB1 signaling, contributing to tolerance, dependence, and withdrawal. Cannabis exerts widespread physiologic effects, including neuropsychiatric complications, cardiovascular changes, respiratory issues, delayed gastric emptying, appetite stimulation, and reproductive endocrine disruption. Cannabis use has been associated with increased propofol requirements, possibly via cytochrome P450 enzyme induction and CB1 receptor downregulation. It may also alter responses to opioids, ketamine, and gabapentinoids, and chronic users often report higher postoperative pain. Cannabis use influences anesthetic dosing, airway and cardiovascular stability, and postoperative pain control. Thorough preoperative assessment, individualized anesthetic planning, and vigilant monitoring are essential, and further research is needed to establish evidence-based perioperative guidelines.