“What was particularly striking was that the concerned patients hospitalised for these disorders were young (and thus, not likely to have their clinical features due to tobacco smoking) and with no history of cardiovascular disorder or cardiovascular risk factors,” senior author Émilie Jouanjus, an associate professor of pharmacology at the University of Toulouse, France, said in an email.

“This is one of the largest studies to date on the connection between marijuana and heart disease, and it raises serious questions about the assumption that cannabis imposes little cardiovascular risk,” paediatrician Dr Lynn Silver, a clinical professor of epidemiology and biostatistics at University of California, San Francisco, said.

“Getting this right is critically important because cardiovascular disease is the top cause of death both in the United States and globally,” Silver, who is also senior adviser at the Public Health Institute, a non-profit public health organisation that analyses marijuana policy and legalisation, said.

Silver is the coauthor of an editorial published with the paper that calls for change in how cannabis is viewed by health professionals, regulatory bodies and the public at large.

“Clinicians need to screen people for cannabis use and educate them about its harms, the same way we do for tobacco, because in some population groups it’s being used more widely than tobacco,” she said.

“Our regulatory system, which has been almost entirely focused on creating legal infrastructure and licensing legal, for-profit (cannabis) businesses, needs to focus much more strongly on health warnings that educate people about the real risks.”

The dangers of smoke (and maybe edibles)

The new systematic review and meta-analysis analysed medical information from large, observational studies conducted in Australia, Egypt, Canada, France, Sweden and the US between 2016 and 2023.

Those studies did not ask people how they used cannabis – such as via smoking, vaping, dabbing, edibles, tinctures or topicals.

Dabbing involves vaporising concentrated cannabis and inhaling the vapour.

However, “based on epidemiological data, it is likely that cannabis was smoked in the vast majority of cases,” Jouanjus said.

Smoking tobacco is a well-known cause of heart disease – both the smoke and the chemicals in tobacco damage blood vessels and increase clotting, according to the US Centres for Disease Control and Prevention.

Therefore, it is not surprising that smoking, vaping or dabbing cannabis could do the same, Silver said: “Any of the many ways of inhaling cannabis are going to have risks to the user, and there’s also secondhand smoke risks, which are similar to tobacco.”

“When you burn something, whether it is tobacco or cannabis, it creates toxic compounds, carcinogens, and particulate matter that are harmful to health,” Cohen said in an email.

However, edibles may also play a role in heart disease, according to a May 2025 study.

People who consumed edibles laced with tetrahydrocannabinol, or THC, showed signs of early cardiovascular disease similar to tobacco smokers.

“We found that vascular function was reduced by 42 per cent in marijuana smokers and by 56 per cent in THC-edible users compared to nonusers,” Dr Leila Mohammadi, an assistant researcher in cardiology at the University of California, San Francisco, told CNN in a prior interview.

The danger of high potency cannabis

None of the studies included in the new meta-analysis asked users about the potency of THC in the products they consume.

Even if they had, that information would be quickly outdated, Silver said.

“The cannabis market is a moving target. It is getting more potent every day,” she said.

“What’s being sold to people today in California is 510 times stronger than what it was in the 1970s. Concentrates can be 99 per cent pure THC. Vapes are over 80 per cent THC.

“A variety of chemically extracted cannabinoids can be almost pure THC, and all of these just have very different effects on people than smoking a joint in the 1970s.”

“We know that more potent cannabis makes people more likely to become addicted,” Silver said.

“We know that more potent cannabis makes people more likely to develop psychosis, seeing and hearing things that aren’t there, or schizophrenia. Habitual users may also suffer from uncontrollable vomiting.”

The rise in potency is one reason that the current study may not have captured the full extent of the risk of marijuana for heart disease, Jouanjus said: “We are afraid that the association might be even stronger than that reported.”

While science continues to study the risk, experts say it’s time to think twice about the potential harms of cannabis use – especially if heart disease is a concern.

“If I was a 60-year-old person who had some heart disease risk, I would be very cautious about using cannabis,” Silver said.

“I’ve seen older people who are using cannabis for pain or for sleep, some of whom have significant cardiovascular risk, or who have had strokes or had heart attacks or had angina, and they have no awareness that this may be putting them at greater risk.”