The Major Surgery Risk for Cannabis Users

Wanna be sedated (during surgery)? Your marijuana habits could be a problem.

by Lara DeSanto Health Writer

Smoke it, vape it, eat it, whatever: Many people use weed on the reg for the potential health benefits, like reduced anxiety or chronic pain management. But if you’ve got surgery or another medical procedure coming up, your cannabis use may endanger you in an unexpected way.

Those who regularly use marijuana may need more than twice the usual level of sedation during routine procedures like colonoscopy, according to a study published in the Journal of the American Osteopathic Association. The study looked at patients who had received endoscopic procedures, and those who smoked or ingested cannabis on a weekly or daily basis required 14% more fentanyl, 20% more midazolam, and a shocking 220% more propofol.

This is alarming news for a number of reasons, researchers say. "Some of the sedative medications have dose-dependent side effects, meaning the higher the dose, the greater the likelihood for problems," said lead researcher Mark Twardowski, D.O., an osteopathic internal medicine physician, in a press release. "That becomes particularly dangerous when suppressed respiratory function is a known side effect [of regular cannabis use]."

There could be other unforeseen issues related to weed use and medications that have yet to be discovered because of a lack of research, Dr. Twardowski said. "Cannabis has some metabolic effects we don't understand, and patients need to know that their cannabis use might make other medications less effective,” he said. “We're seeing some problematic trends anecdotally, and there is virtually no formal data to provide a sense of scale or suggest any evidence-based protocols.”

The “problematic trends” he’s referring to? More ER patients reporting chronic nausea (which can happen if you toke up often), patients who need much higher doses for general anesthesia during surgery, and higher rates of post-op seizures.

Twenty-four million people age 12 or older are current marijuana users, according to the 2017 National Survey on Drug Use and Health — and the numbers are on the rise, especially in adults over age 26.

Dr. Twardowski and his fellow researchers hope the increasing use of cannabis throughout the country will prompt even more research and data collection to help keep patients safe.

"This study really marks a small first step," says Dr. Twardowski. "We still don't understand the mechanism behind the need for higher dosages, which is important to finding better care-management solutions."

Lara DeSanto
Meet Our Writer
Lara DeSanto

Lara is a former digital editor for HealthCentral, covering Sexual Health, Digestive Health, Head and Neck Cancer, and Gynecologic Cancers. She continues to contribute to HealthCentral while she works towards her masters in marriage and family therapy and art therapy. In a past life, she worked as the patient education editor at the American College of OB-GYNs and as a news writer/editor at