Researchers have discovered that cannabis use doubles the risk of developing severe COVID infections and hospitalizations.

Previous studies have identified that several factors could heighten an individual's susceptibility to developing severe COVID-19 infection. These include advanced age, a history of smoking, elevated body mass index (BMI), and the presence of comorbidities such as diabetes.

Since the onset of the pandemic, numerous studies have highlighted both the protective and harmful effects of cannabis use in relation to COVID-19 infection.

In a study published in the journal JAMA Network Open, researchers from the Washington University School of Medicine in St. Louis found that cannabis use is associated with a heightened risk of severe illness in individuals with COVID-19.

"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. 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. People who reported yes to current cannabis use, at any frequency, were more likely to require hospitalization and intensive care than those who did not use cannabis," said Dr. Li-Shiun Chen, senior author of the study.

The findings were derived from an analysis of deidentified electronic health records of COVID patients who visited BJC HealthCare hospitals and clinics in Missouri and Illinois between Feb. 1, 2020, and Jan. 31, 2022. Apart from the information on sex, age, and race, data included patients' history of having other medical conditions such as diabetes and heart disease. It also recorded their use of tobacco, alcohol, cannabis, and vaping. The outcomes of the illness were also documented, specifically hospitalization, intensive-care unit (ICU) admittance, and survival.

"The researchers found that people who reported using any form of cannabis at least once in the year before developing COVID-19 were significantly more likely to need hospitalization and intensive care than were people with no such history. This elevated risk of severe illness was on par with that of smoking," the news release stated.

Contradicting previous studies that suggest the benefits of cannabis on COVID-19, the study results indicated that cannabis users had an 80% increased risk of hospitalization and a 27% increased risk of ICU admission. These findings remained significant even after accounting for other factors such as tobacco smoking, vaccination status, other health conditions, date of diagnosis, and demographic factors.

"Most of the evidence suggesting that cannabis is good for you comes from studies in cells or animals. The advantage of our study is that it is in people and uses real-world healthcare data collected across multiple sites over an extended time period. All the outcomes were verified: hospitalization, ICU stay, death. Using this data set, we were able to confirm the well-established effects of smoking, which suggests that the data are reliable," Chen said.