Anesthesia and medical cannabis: an integrated approach

Cannabis use, both medical and recreational, is increasing and poses a growing challenge for anesthesiologists, given the scarcity of specific clinical data. The main phytocannabinoids, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), interact with CB1 and CB2 receptors, affecting cardiovascular, respiratory, neurological, and immune systems, as well as the metabolism of several anesthetic drugs. Chronic or high-dose use can alter anesthetic requirements, increase risk of perioperative complications, and modify postoperative pain responses, often leading to greater opioid consumption. ASRA and PAIN guidelines recommend universal preoperative screening, assessment for cannabis use disorder, dose tapering or discontinuation in high-use patients, and postponement of elective procedures in the presence of acute intoxication. Differentiating medical use - characterized by standardized formulations and titrated dosing - from recreational use, which is more variable and often associated with polysubstance use, is essential. Cardiovascular (tachycardia, hypotension, arrhythmias), respiratory (bronchitis, airway hyperreactivity), and neurological (cognitive impairment, delirium risk) effects require targeted intra- and postoperative monitoring. Multimodal analgesic strategies, opioid-sparing approaches, and postoperative nausea/vomiting prevention are recommended. The pain specialist plays a key role in managing chronic therapy patients, avoiding abrupt discontinuation and preventing withdrawal syndrome, including through oral cannabinoid substitution. A multidisciplinary approach involving anesthesiologists, pain specialists, and pharmacologists, integrating thorough history-taking, risk assessment, and personalized perioperative planning, is essential to optimize safety and outcomes in surgical patients who consume cannabis.