Cannabis use tied to increased risk of severe COVID-19

July 8, 2024
Similar to smokers, cannabis users nearly twice as likely to need hospitalization, intensive care when infected with the virus.

A new study by researchers at Washington University School of Medicine in St. Louis links cannabis use to an increased risk of serious illness for those with COVID-19.

The study, published June 21 in JAMA Network Open, analyzed the health records of 72,501 people seen for COVID-19 at health centers in a major Midwestern healthcare system during the first two years of the pandemic. 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 from smoking.

Cannabis use was different than tobacco smoking in one key outcome measure: survival. While smokers were significantly more likely to die of COVID-19 than nonsmokers — a finding that fits with numerous other studies — the same was not true of cannabis users, the study showed.

The study analyzed deidentified electronic health records of people who were seen for COVID-19 at BJC HealthCare hospitals and clinics in Missouri and Illinois between Feb. 1, 2020, and Jan. 31, 2022. The records contained data on demographic characteristics such as sex, age and race; other medical conditions such as diabetes and heart disease; use of substances including tobacco, alcohol, cannabis and vaping; and outcomes of the illness — specifically, hospitalization, intensive-care unit (ICU) admittance and survival.

COVID-19 patients who reported that they had used cannabis 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, after taking into account tobacco smoking, vaccination, other health conditions, date of diagnosis, and demographic factors. For comparison, tobacco smokers with COVID-19 were 72% more likely to be hospitalized and 22% more likely to require intensive care than were nonsmokers, after adjusting for other factors.

These results contradict some other research suggesting that cannabis may help the body fight off viral diseases such as COVID-19.

Washington University School of Medicine in St. Louis release on Newswise