Cannabis use doubles the risk of dying from heart disease

Cannabis use increases the risk of major adverse cardiovascular events (MACE), as shown in a robust meta-analysis, raising serious questions about the assumptions that cannabis use poses little cardiovascular (CV) risk among users.

The pooled risk ratios from 24 epidemiological studies published between January 2016 and January 2023 were 1.29 (95 percent confidence interval [CI], 1.05–1.59) for acute coronary syndrome, 1.20 (95 percent CI,1.13–1.26) for stroke, and 2.10 (95 percent CI,1.29–3.42) for CV death. [Heart 2025;doi:10.1136/heartjnl-2024-325429]

What was more concerning was the “doubling in the risk of dying from cardiovascular disease” (CVD), according to the authors. “Some people have a very positive image about cannabis use, so it’s important to have information about the risks of smoking cannabis.”

While previous studies have linked cannabis use to CV problems, the full extent of the risk has not been clarified until this meta-analysis.

Risks, issues, and repeating history

“What we bring with this meta-analysis is that we quantify the associations,” said senior author Emilie Jouanjus, also from the University of Toulouse, INSERM, France, noting that there are implications for both disease prevention and management. She added that the idea behind the study is not to demonise cannabis but “to make people aware of the increased risks.”

Meanwhile, Dr Robert Page II from the University of Colorado in Aurora, Colorado, US, commented that with meta-analyses, “I don’t put a lot of faith in the magnitude, but I put a lot of faith in that there’s an issue here.”

He added that the findings provide a significant signal and can serve as a helpful starting point for clinicians’ and patients’ discussions. He also emphasized the importance of awareness, not just among patients with a history of CVD. “For clinicians, particularly cardiologists, we have to be asking this at each patient encounter now.”

Page pointed out that it took decades for the world to recognize the harms of tobacco. “If we don’t talk about the risks associated with [cannabis], we’re going to repeat history, and it’s not going to be pretty.”

The recent findings of cannabis’ role as a risk factor for atherosclerotic CVD follow on from another study, which showed that cannabis smoking is associated with endothelial dysfunction. [JAMA Cardiol 2025:e251399]

In a separate editorial, Drs Stanton Glantz and Lynn Silver from the University of California in San Francisco, US, also highlighted the consequences of shifts in thinking amid the legalization of cannabis in many countries.

“Frequent cannabis use has increased recently, and many users believe it is a safe and natural way to relieve pain or stress,” they said. “However, a growing body of evidence links cannabis use to significant harms throughout life, including CV health. [Heart 2025;doi:10.1136/heartjnl-2025-326169] There are also several short-term and long-term adverse effects associated with cannabis use, including impairments to respiratory and cognitive functions.

“Cannabis use, like tobacco and alcohol use, should be assessed in all patients,” Glantz and Silver emphasized. “At least in the US, health professionals are the most influential source of cannabis information … making it important for clinicians to educate all patients about cannabis risks, and take this into account in clinical decision-making.”

Cannabis risks also need to be incorporated into the framework for CVD prevention. “So too must CVD prevention be incorporated into the regulation of cannabis markets. Effective education on risks must be developed and implemented,” Glantz and Silver added.

24 studies, 200 million people

In the meta-analysis, the researchers pooled data from 24 studies (17 cross-sectional, six cohort, and one case-control) involving approximately 200 million people. The average age of participants across the studies ranged from 19–59 years. [Heart 2025;doi:10.1136/heartjnl-2024-325429]

Cannabis users were generally younger than nonusers, and most participants were male. Only one study examined the medical use of cannabis. All but five of the papers controlled for tobacco use, which is important because tobacco use is common among cannabis users, and it is a potentially important confounder, said the authors.

Heightened risks for cannabis use

Compared with nonuse, cannabis use increased the risks of MACE. An analysis restricted to the cohort studies showed similar results.

The authors said the plausible mechanisms for the elevated risks include vasospasm and the pleiotropic effects of cannabinoids, such as cannabidiol and tetrahydrocannabinol, which act through various pathways.

When the type 1 cannabinoid receptor is activated, this can result in “oxidative stress, tissue injury, cell death, proatherogenic, profibrotic, proinflammatory effects and vasodilation/vasoconstriction via the sympathetic nervous system,” they added. “Conversely, activation of the type 2 receptor reduces inflammation and oxidative stress.”

The researchers said their work was an exhaustive analysis of published data on the potential association between cannabis use and adverse CV events and provided new insights from real-world data. “The findings should raise overall awareness of cannabis’ potential to cause CV harm,” they added.