Does Marijuana Interfere With Anesthesia?

Medically Reviewed By William C. Lloyd III, MD, FACS
Close-up of hand holding smoking marijuana cigarette

The short answer: Yes, marijuana interferes with anesthesia. As uncomfortable as it may be to disclose substance use to your healthcare providers, it is essential if you want to receive top-notch care. If you regularly smoke weed or use cannabis-based products and do not tell your healthcare providers about your use, your body may not receive enough anesthetic or pain medication to be effective.

Learn more about marijuana and anesthesia, including how to talk about marijuana use with your anesthesiologist or nurse anesthetist.

Marijuana and Anesthesia

Doctors and researchers have found that patients who use marijuana usually require more anesthetic medication to achieve adequate numbing and relaxation. One study found that regular marijuana users (defined as using at least weekly) needed more than 3 times as much total anesthetic as nonusers to reach the level of sedation for endoscopies.

So, if you’re scheduled for a colonoscopy, it’s a good idea to be honest with your anesthesiologist about your cannabis use. If you don’t tell your provider about your marijuana use, or under-report your usage, you may have a more unpleasant experience, as it will likely take longer to perform the procedure and you may not be as “out” of it as you’d like.

Another study found that patients who used cannabis and required surgical repair of a broken leg needed more anesthetic and pain medicine than patients who underwent the same surgical repair but did not use cannabis.

There is also some evidence that smoking weed may cause airway hyperreactivity, just as cigarette smoking does. This hyperreactivity can cause problems with breathing during and after surgery. An anesthesiologist or nurse anesthetist who is aware of this risk is better positioned to respond quickly, should problems occur.

How to Talk About Marijuana Use With Healthcare Providers

Before any surgery or medical procedure requiring anesthesia, a healthcare provider will ask you a lot of questions about your health and health habits. These questions are designed to identify any potential issues so your medical team can treat you appropriately. When the provider asks about drug and alcohol use, share the details of your marijuana use, regardless of whether marijuana use is legal in your state. Your healthcare providers will not disclose any information you share with them to law enforcement or anyone not directly involved in your healthcare.

Be honest about your use; don’t downplay or underestimate how much you use. Remember: marijuana use can impact the effectiveness of your anesthetic and pain medicine, so honest disclosure is your best chance at a comfortable procedure.

Tell your provider what form (or forms) of cannabis you use, how much you use, and how frequently you use. Your provider will take this information into consideration when planning your anesthesia and postoperative pain relief.

It is not a good idea to undergo surgery or an endoscopy while under the influence of marijuana. If possible, stop using marijuana at least 72 hours before a scheduled colonoscopy, surgery or other medical procedure requiring anesthesia or sedation.

The American Society of Anesthesiologists has urged the federal government to allow more research into the effects of marijuana on anesthesia and human health.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Mar 17
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