Should I tell my anesthesiologist that I use cannabis?

Specialty guidance says yes. The 2023 ASRA Pain Medicine consensus guidelines on the perioperative patient on cannabis and cannabinoids recommend universal screening before surgery, taking into account the type of product used, the route of administration, typical frequency and amount, and the most recent use. Research suggests the specifics matter more than a simple yes or no, because route and frequency are what the estimates in the literature track most closely.

How long before surgery should you stop using cannabis?

Patient guidance from the American College of Surgeons advises not using cannabis products within 72 hours of general anesthesia. Timing depends on the procedure, the anesthetic plan, and the individual, so the window is a question for the surgical team rather than something to decide alone. Abruptly stopping a regular routine can carry its own adjustment, which is another reason to raise it early.

Is the research on cannabis and anesthesia settled?

No. Studies indicate a consistent direction but an unsettled size. Two retrospective studies found cannabis users received more anesthetic agent, while a 2023 quality improvement project published in the Journal of PeriAnesthesia Nursing found no differences in anesthetic requirements, complications, or recovery unit length of stay. What the guidelines rest on is not a precise adjustment but the value of the care team knowing in advance.

Cannabis Before Surgery: What New Research Says About Telling Your Care Team

Q: Does cannabis use change how much anesthesia you need?

Early findings suggest a modest association. A retrospective cohort study published in the British Journal of Anaesthesia on September 29, 2026 reviewed 341,199 adult patients and found non-medical cannabis use was associated with propofol doses higher by 6.85 micrograms per kilogram per minute, and medical cannabis certification with 2.87. The authors noted these effect sizes were smaller than previously reported and called for prospective studies on clinical relevance, so this is an association in records rather than a settled dosing rule.

A surgery date usually arrives with a short list of instructions. Nothing to eat after midnight, pause certain supplements, arrange a ride home. Cannabis rarely appears on that list, and plenty of New Yorkers assume it does not belong there. Anesthesiologists have been arguing otherwise for several years, and the evidence behind that argument just got considerably larger.

A retrospective cohort study published in the British Journal of Anaesthesia on September 29, 2026 is the most detailed look yet at whether cannabis use changes what happens in an operating room. The findings are worth understanding for anyone in New York who consumes regularly and has a procedure coming up, and the practical takeaway is simpler than the statistics.

What the New Study Actually Measured

Researchers affiliated with Harvard Medical School reviewed records for 341,199 adults who received either propofol sedation or volatile-based general anesthesia at Beth Israel Deaconess Medical Center between 2008 and 2024. Within that group, 23,896 patients, about 7.0 percent, were identified as non-medical cannabis users, and 3,193, about 0.9 percent, held a certification for medical cannabinoids.

After adjusting for other factors, both groups were associated with higher doses of the primary anesthetic agent. Non-medical cannabis use was associated with propofol doses higher by 6.85 micrograms per kilogram per minute, and medical certification with 2.87. Estimates were strongest among the most frequent consumers: daily recreational users sat 8.41 micrograms per kilogram per minute above the comparison group. For inhaled anesthetics, the differences worked out to roughly 0.01 to 0.02 additional MAC, a standard measure of anesthetic depth. At comparable induction doses, non-medical users also showed a slightly larger heart rate rise after intubation, on the order of 1.45 beats per minute.

The authors were notably restrained about what this means. Their own conclusion described the differences as modest, noted that the effect sizes were smaller than earlier studies had reported, and called for prospective research to establish whether the gap is clinically relevant. This is a single-center record review with self-reported exposure, which is a real limitation and one the paper names.

A Consistent Direction, an Unsettled Size

Smaller studies have pointed the same way. A 2023 analysis in the Journal of Oral and Maxillofacial Surgery looked at 189 patients undergoing ambulatory dental extractions, 57 of whom reported regular cannabis use, and found users received significantly more propofol, roughly 153 milligrams against 118 milligrams for non-users.

The picture is not unanimous, and it would be misleading to present it as such. A 2023 quality improvement project in the Journal of PeriAnesthesia Nursing compared cannabis users against non-users at one hospital and found no differences in anesthetic requirements, complications, or recovery unit length of stay. Taken together, the literature supports a direction more confidently than it supports a number.

That distinction matters, because the case for mentioning cannabis was never that a clinician needs to add a precise extra dose. It is that surprises during anesthesia are worth avoiding.

The Guidance Already Exists

In 2023 the American Society of Regional Anesthesia and Pain Medicine published the first United States consensus guidelines on managing surgical patients who use cannabis and cannabinoids. The committee worked through nine key questions using a modified Delphi method, requiring at least 75 percent agreement for a recommendation, and reached full consensus on third-round voting.

The first recommendation is universal screening before surgery, covering the type of cannabinoid product, the route of administration, typical frequency and amount, and most recent consumption. Other recommendations address when to postpone an elective procedure, how cannabis interacts with perioperative opioids, intraoperative adjustments, and postoperative monitoring.

Patient-facing guidance from the American College of Surgeons is more specific on timing. It advises against using cannabis products within 72 hours of general anesthesia, and flags three concerns: smoke and vapor can irritate the airway and make intubation more difficult, cannabis can shift heart rate and blood pressure, and patients with prior cannabis use have reported higher postoperative pain and needed more opioid medication for longer.

The Disclosure Gap Cuts Both Ways

One detail from that 2023 nursing study is easy to skip past and genuinely useful. Before a structured screening process was introduced, anesthesia providers conducting pre-anesthetic assessments identified cannabis use in just 4.08 percent of patients. After the intervention, that rose to 14.36 percent. Nursing identification moved from 11.22 to 13.81 percent.

Given that roughly 7 percent of patients in the much larger Boston cohort were identified as non-medical users, a baseline detection rate of 4 percent suggests the shortfall is partly a matter of the question not being asked. That is a reason to volunteer the information rather than wait for it to come up.

What to Do With This Before a Procedure

None of the following is medical advice, and the decisions belong with the clinicians running the case. It is a short list of what the research suggests is worth putting on the table.

Be specific rather than binary. Smoked flower, a vaporizer, an edible, and a tincture behave differently, and the studies that found the largest associations were looking at frequency. Daily use is different information from occasional use.

Ask about the window instead of guessing. The 72 hour figure is general patient guidance, not a rule tailored to a specific procedure or anesthetic plan.

Expect pain planning to come up. The overlap between cannabis and postoperative pain management is one of the more active research areas, and it connects to what we have written about cannabis and chronic pain research.

A planned pause is a known quantity. If a break is part of the plan, knowing what to expect from it helps. Our guide to what research says about tolerance breaks covers the adjustment period in more detail.

Why This Is Worth Knowing in New York

The pool of surgical patients who consume cannabis from a regulated shelf keeps growing here. The Office of Cannabis Management and Cannabis Control Board annual report released in January 2026 reported more than 2.5 billion dollars in adult-use retail sales since legalization, including 1.6 billion dollars in 2025, with licensed storefronts nearly doubling from 261 in 2024 to 556 in 2025.

One practical advantage of buying from a licensed shop is that the product carries a tested label. Knowing the cannabinoid and terpene detail on a Greenline package, and being able to describe the format and how often you use it, is precisely the information a pre-anesthetic assessment is looking for. Reading a label closely is a habit that pays off well beyond the counter, which is the argument our guide to strain categories makes from a different angle.

Research in this area is still developing, and the newest and largest study is the one urging caution about how much the differences matter. What the evidence supports today is modest and useful: a short, specific sentence to your care team is low cost, and it lets people whose job is your safety plan with better information.

References

Ratajczak N, Ahrens E, Wachtendorf LJ, et al. Cannabis use and anaesthetic agent dosing in patients undergoing surgery or interventional procedures: a single-centre retrospective cohort study. British Journal of Anaesthesia. 2026 Sep 29 (online ahead of print). doi:10.1016/j.bja.2026.09.001
Shah S, Schwenk ES, Sondekoppam RV, et al. ASRA Pain Medicine consensus guidelines on the management of the perioperative patient on cannabis and cannabinoids. Regional Anesthesia & Pain Medicine. 2023;48(3):97-117. doi:10.1136/rapm-2022-104013
Ripperger D, Atte A, Ritto F. Cannabis users require more anesthetic agents for general anesthesia in ambulatory oral and maxillofacial surgery procedures. Journal of Oral and Maxillofacial Surgery. 2023;81(12):1460-1465. doi:10.1016/j.joms.2023.09.008
Stover J, Sabol VK, Eastman A, Simmons VC. Preoperative preparation and guidelines for cannabis-using patients undergoing elective surgery. Journal of PeriAnesthesia Nursing. 2023;38(4):560-563. doi:10.1016/j.jopan.2022.10.002
American College of Surgeons. Marijuana and Surgery, patient education. facs.org
New York State Office of Cannabis Management and Cannabis Control Board. 2025 Annual Report, released January 2026. cannabis.ny.gov