Cannabis Use and Severe COVID-19 Are Linked

A new study suggests that cannabis users are almost twice as likely to require hospitalization and intensive care when contracting COVID.

Since the start of the COVID-19 pandemic in 2020, researchers have been working hard to determine who faces an increased risk of experiencing severe outcomes, and a new study suggests cannabis users are on that list.

Conducted by researchers at Washington University School of Medicine in St. Louis and published in JAMA Network Open, the study aimed to determine whether cannabis use might be a risk factor for severe infection, as previous studies on the subject have produced contradictory results — with some even suggesting that cannabis may help the body fight off viral infections.


But these previous studies were mostly based on cells or animals, while this one is based on real-world healthcare data.

In the study, researchers found that cannabis use was, in fact, associated with an almost doubled risk of needing hospitalization and intensive care — similar to the risk level faced by tobacco smokers.

“There’s this sense among the public that cannabis is safe to use, that it’s not as bad for your health as smoking or drinking, that it may even be good for you,” said senior author Li-Shiun Chen, M.D., DSc, a professor of psychiatry, in a news release. “I think that’s because there hasn’t been as much research on the health effects of cannabis as compared to tobacco or alcohol. What we found is that cannabis use is not harmless in the context of COVID-19.”

Researchers conducted the study by analyzing health records from 72,501 people treated for COVID-19 at BJC HealthCare hospitals and clinics in Missouri and Illinois between Feb. 1, 2020, and Jan. 31, 2022.

They found that those who had reported using cannabis in any form at least once in the previous year were 80% more likely to be hospitalized and 27% more likely to be admitted to the ICU than patients who had not used cannabis, even after taking into account tobacco smoking, vaccination, other health conditions, date of diagnosis, and demographic factors.

Tobacco smokers with COVID-19 were meanwhile 72% more likely to be hospitalized and 22% more likely to require intensive care than nonsmokers.

However, one significant difference between cannabis and tobacco use was found: the risk of death. While tobacco users were significantly less likely to survive their COVID-19 infection, the same was not true for cannabis users.

While the study doesn’t address why cannabis might increase the risk of severe outcomes, the authors suggest that it may be because inhaling cannabis smoke injures delicate lung tissue and makes it more vulnerable to infection. But that doesn’t mean edibles are harmless, either. As cannabis in all forms is known to suppress the immune system, the authors say it may impact the body’s ability to fight off viral infections no matter how it is consumed.


The authors say they hope their findings will lead to further research on the health effects of cannabis.


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