smoking weed regularly has serious health risks, including death after surgery

cannabis use disorder has been linked to post-surgery complications, increased infections and mental health issues.

by karen hawthorne

published jul 21, 2023

5 minute read

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5 minute read

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smoking weed regularly has serious health risks, including after surgery

about one in five americans use cannabis, and among those, about three in 10 will develop cannabis use disorder. hector vivas/getty images

if you’re smoking weed or eating cannabis gummies to relax and unwind, be aware that it’s a habit that comes with potential harm. “i think people view recreational cannabis use as being harmless,” says dr. paul potnuru, anesthesiologist and researcher at the department of anesthesiology, critical care and pain medicine at mcgovern medical school, part of the university of texas health science center, uthealth houston. “the problem with that is we don’t really know when you cross over from recreational use into more harmful use.”

potnuru explains that opinions on cannabis use tend to occupy two ends of the spectrum.

“one end says ‘hey, cannabis is just bad. nobody should use it ever. we should just ban it.’ then there are those who say, ‘hey, cannabis is natural. it’s the best thing ever. you can use it all the time, everyone can use it, and it should be widely available and legal,'” he says, adding that unlike tobacco or alcohol, there’s still a lot to learn about the amounts at which cannabis becomes harmful.

how much cannabis are you consuming?

one of the challenges in figuring out the effects of cannabis is the increasing amount of the active component thc — or tetrahydrocannabinol — which is much higher now than in the early 1990s, says potnuru. it’s hard to tell how much people are actually consuming — when you consume an edible, for example, is that equal to one joint or two joints?

another concern is that the rising use of cannabis is leading to substance dependence, he adds. in fact, statistics canada reports that by the end of 2020, 7.9 per cent of canadians aged 15 and older used cannabis daily or almost daily, with similar prevalence for males and females, and higher for people aged 18 to 44 than those aged 45 and older. health canada says that daily use puts the risk of addiction at 25 to 50 per cent.

about one in five americans use cannabis, and among those, about three in 10 will develop cannabis use disorder, characterized by food cravings or decreased appetite, restlessness, irritability, and mood and sleep difficulties after quitting, according to the u.s. national institute on drug abuse. another telltale sign of the disorder is the inability to stop using even when it’s negatively interfering with daily life.

cannabis use disorder increases chance of complications after surgery

but the negative impacts of overusing cannabis don’t stop there.

potnuru is the first author of a breakthrough uthealth houston study that appeared in the journal jama surgery which demonstrated the heightened risk for people with cannabis use disorder for serious complications after major elective surgery.

researchers looked at data from the 2016 to 2019 national inpatient sample database of 12,422 hospitalizations that happened after 11 types of major elective, noncardiac surgery. these surgeries included hip or knee replacement, hernia repair, gall bladder or colon surgery, breast lump biopsy, mastectomy or hysterectomy, spinal fusion and lumbar disk surgery.

more than 6,200 of the patients had cannabis use disorder. for the study, they were matched with people who were not dependent or addicted to cannabis. researchers found that patients with cannabis use disorder were more likely to experience heart attacks, strokes, acute kidney injury, respiratory failure, blood clots, infections and in-hospital death.

cannabis can lead to heart attacks

and while potnuru says that cannabis can’t be definitively blamed for these complications, the link is apparent.

“the main mechanism identified so far is that cannabis can cause your blood vessels to spasm, so that’s what leads to these strokes and heart attacks that have been found in previous studies,” he says. “and if you’re an acute user or if you’ve been using for a long time or you’ve just recently used a lot, it can increase your heart rate and stress your heart out more.”

cannabis is also a known immunosuppressant, reducing the body’s ability to fight off infections, which can leave you more vulnerable after surgery. potnuru notes that patients who are already immunosuppressed, like those with inflammatory bowel disease (ibd) or rheumatoid arthritis who take immunosuppressants, are known to have higher infection rates after surgery.

cannabis users need more anesthetic

to put his research focus in context, potnuru works in an anesthesia clinic where he sees elective surgery patients to make sure they’re in the best health possible leading up to surgery. a lot of what he does is risk stratification, figuring out who is high-risk, who is low-risk, and then helping optimize the high-risk patients for surgery. if patients consume alcohol or tobacco, doctors will counsel them early on to consider cutting back or stopping completely so they are in the best medical condition to undergo surgery and manage recovery. he also refers to research that shows patients who use cannabis frequently need more anesthetic to achieve the same degree of sedation as those who use less.

like potnuru, clinical physician and addiction expert dr. vera tarman also stresses the physical effects of cannabis use disorder, including frequent episodes of bronchitis, chronic congestion and weight loss, along with the psychological impact on mood and increased anxiety.

as the medical director of the renascent residential addiction rehabilitation centre in toronto, tarman has a front-row seat to the effects of increased cannabis use, saying that patients often describe it as “taking over their lives.”

cannabis is “taking over their lives”

“they can keep paying their rent, but they’re not going out doing anything or working. they might be on disability or something because they’re stuck in their basement smoking pot all the time,” she says. “we’re now seeing people coming in with cannabis use disorder on a weekly to monthly basis — before, it was maybe once every six months. it was the rare person that came in thinking, ‘i’m here just for pot and other people are here for fentanyl.’ now we see people coming in where cannabis is their sole addiction.”

tarman is also concerned about the popularity of cannabis among adolescents and preteens who face a higher risk of becoming addicted because their brains are still developing.

“it’s become much like alcohol,” she says. “i have nothing against alcohol, if a person is having one or two drinks, maybe occasionally three on a happy day, but we’re seeing the people that can’t stop at just one. that’s happening with marijuana as well, and we have to realize that we can’t diminish marijuana as harmless. its effects are as relevant as any other addictive drug.”

part of tackling this is education, says potnuru, who would like to see health-care providers screen people early for cannabis use as part of their standard care process. this would help to increase awareness of the potential risks, but also possibly change their perspectives on cannabis safety.

“a lot of times people develop a habit, they don’t realize it’s bad, and then their doctor says, ‘that can be harmful. maybe you should think about cutting down.’ and that prompts people to start seeking treatment or maybe rethink their own use.”

karen hawthorne is a toronto-based writer.

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karen hawthorne

karen hawthorne worked for six years as a digital editor for the national post, contributing articles on health, business, culture and travel for affiliated newspapers across canada. she now writes from her home office in toronto and takes breaks to bounce with her son on the backyard trampoline and walk bingo, her bull terrier.

smoking weed regularly has serious health risks, including death after surgery