Preoperative cannabinoid exposure and postoperative pain: A narrative review.

BACKGROUND: Cannabis use is increasingly common, yet its effects on postoperative pain and opioid requirements remain unclear. While cannabinoids are used in chronic pain, their role in acute perioperative recovery is less defined.

METHODS: A systematic search of PubMed, CINAHL, and Embase identified studies published within the past ten years that examined preoperative cannabis use and its relationship with postoperative pain and opioid consumption. Forty-two studies met the inclusion criteria. Data were extracted and summarized using a narrative synthesis methodology.

RESULTS: Exposure definitions, surgical specialties, and outcome metrics were heterogeneous, limiting cross-study comparability; therefore, effects were reported in their native form without pooling. Of the 42 included studies, 14 (33.3 %) found that cannabis users reported higher postoperative pain, 10 (23.8 %) reported no difference, 2 (4.8 %) suggested reduced pain, and 16 (38.1 %) did not report pain outcomes. Regarding opioids, 18 studies (42.9 %) indicated greater postoperative requirements, 17 (40.5 %) found no difference, 3 (7.1 %) suggested reduced use, and 4 (9.5 %) did not report opioid outcomes. Specialty-specific patterns emerged: mixed cohorts (90 %) and spine populations (55 %) more frequently reported increased opioid use, whereas arthroplasty studies more often reported no difference (62 %). Limited, low-certainty evidence suggested that resuming cannabis after discharge was associated with lower persistent opioid use.

CONCLUSIONS: Preoperative cannabis exposure is associated with increased postoperative pain and opioid requirements in some, but not all, surgical contexts. Outcomes vary by specialty, and residual confounding and nonstandardized exposure measurement constrain inference, underscoring the need for standardized exposure definitions, prospective designs, and individualized perioperative pain strategies.