GRAND RAPIDS, Mich. — As cannabis use becomes more mainstream, doctors are raising concerns about how it can affect patients during surgery.

Medical experts say marijuana can stay in the body longer than many people realize, especially when consumed regularly through smoking, vaping or edibles. That lingering presence can interfere with how anesthesia works, which could make surgeries riskier.

When cannabis is in the system, it can lead to prolonged and unpredictable effects because it is metabolized by the same enzymes that process many anesthesia drugs. As a result, doctors may need to use higher doses to keep patients sedated.

Cannabis use can also raise heart rate, impact blood pressure, and make pain more difficult to manage after surgery. In some cases, it can increase airway activity, which can lead to complications like laryngospasm or bronchospasm—conditions that make it harder for medical staff to keep patients oxygenated during the procedure. It can also delay gastric emptying, another risk during surgery.

Doctors say the best way to reduce these risks is simple: be honest. Patients should be upfront about any cannabis use—daily, occasional or edible—even if it’s legal.

“Cannabis isn’t harmless,” Dee Berry, CRNA & President of Michigan Association of Nurse Anesthetists said. “We’re not here to judge you. We just want to make the best plan of care.”

Physicians encourage patients to answer pre-surgery questions truthfully so medical teams can properly adjust care plans and avoid preventable complications.