Major study finds cannabis use may double heart disease deaths and boost stroke risk by 20%

Cannabis, often perceived as a low-risk recreational drug, could pose a far deadlier threat than previously understood. A sweeping global review led by researchers at the University of Toulouse has found that cannabis users may face up to double the risk of dying from cardiovascular disease and a 20% higher chance of suffering a stroke.

The findings, published in the journal Heart, challenge assumptions around the drug’s safety, especially as legalisation and usage rates surge worldwide. Experts are now urging health regulators to treat cannabis with the same seriousness as tobacco, warning that the modern drug market is neglecting the growing evidence of harm.

Researchers analysed 24 studies published between 2016 and 2023, covering around 200 million individuals. The majority of study participants were aged between 19 and 59, with cannabis users skewing younger and more likely to be male. Among the studies included were 17 cross-sectional studies, six cohort studies, and one case-control study—each probing links between cannabis consumption and cardiovascular outcomes.

The results were alarming: users faced a 29% higher risk of acute coronary syndrome, a 20% higher risk of stroke, and—most dramatically—twice the risk of dying from heart disease.

Although the authors acknowledged some limitations in the analysis, including a moderate to high risk of bias in several studies and unclear data on how cannabis use was measured, they insisted the findings were “an exhaustive analysis of published data.” The scale of the study, they said, offers critical insight into cannabis’s impact on real-world cardiovascular health.

“The findings outlined by this meta-analysis should enhance the general awareness of the potential of cannabis to cause cardiovascular harm,” the researchers said.

In a strongly worded editorial published alongside the study, public health experts Prof Stanton Glantz and Dr Lynn Silver from the University of California, San Francisco, warned the implications could be far-reaching. “The analysis raises serious questions about the assumption that cannabis imposes little cardiovascular risk,” they wrote.

They pointed out that cannabis products today are not what they were a decade ago. The modern market now includes high-potency concentrates, synthetic cannabinoids, and edibles—all of which may have unique health risks. “How these changes affect cardiovascular risk requires clarification,” they added, noting that it’s still unclear whether the risks stem primarily from the cannabinoids themselves or other compounds inhaled during use.

Glantz and Silver argued that cannabis must be treated more like tobacco—legal but heavily discouraged. “Effective product warnings and education on risks must be developed, required, and implemented,” they wrote. “Cardiovascular and other health risks must be considered in the regulation of allowable product and marketing design.”

While some campaigners have focused on legalisation and decriminalisation—such as Sadiq Khan’s calls for partial cannabis reform—the new findings may shift public debate. Critics of relaxed cannabis policy have long warned of underexplored health consequences, particularly on vulnerable groups and young users.

The editorial concluded with a sharp message for policymakers: “Today’s regulation focuses too much on creating a legal market, with woeful neglect of minimising health risks. This must change.”

As more countries legalise or relax cannabis laws, calls are growing for deeper research, stronger health warnings, and stricter rules on marketing and public exposure. The high may be temporary—but for some, the consequences could be fatal.