The conversation around cannabis has shifted dramatically over the past decade. As legalisation sweeps across nations and the substance becomes increasingly normalised, a troubling pattern has emerged in medical research that demands urgent attention. The link between cannabis and heart attack risk has become undeniable, with young, seemingly healthy adults experiencing cardiac events at rates that have left cardiologists alarmed.

The Six-Fold Risk That Changed Everything

In March 2025, research published in JACC Advances sent shockwaves through the medical community. The study examined over 4.6 million adults under the age of 50, people who should be at their cardiovascular peak. These weren’t individuals with pre-existing heart conditions, high blood pressure, or unhealthy cholesterol levels. They didn’t have diabetes. They didn’t smoke tobacco. By every traditional measure, they should have been safe from heart attacks.

Yet those who used cannabis faced a staggering reality: they were more than six times as likely to suffer a heart attack compared to non-users.

The numbers tell an even grimmer story. Cannabis users in this study also demonstrated a four-fold increased risk of stroke, double the risk of heart failure, and triple the risk of dying from cardiovascular events. These aren’t marginal increases. They represent a fundamental threat to heart health that has gone largely unrecognised by the public.

When Daily Use Becomes Deadly: Cannabis and Heart Attack Risk

A separate study examining 430,000 American adults, published in the Journal of the American Heart Association, revealed the dose-dependent nature of cannabis and heart attack risk. Daily users showed 25% higher odds of heart attack and 42% higher odds of stroke compared to those who abstained entirely; the more frequently someone used cannabis, the higher their cardiovascular risk climbed.

What makes these findings particularly significant is their rigour. Researchers controlled for every confounding factor they could identify: tobacco use, alcohol consumption, body mass index, diabetes, physical activity levels. The cardiovascular risks persisted regardless. Even among people who had never touched a cigarette or vaping device, cannabis use independently increased their chances of heart attack and stroke.

How Cannabis Damages Your Heart

Understanding why cannabis harms the heart requires looking at the body’s endocannabinoid system. This complex network of receptors exists throughout the cardiovascular system, including in the heart muscle itself, blood vessel walls, and the cells that line our arteries.

THC, the primary psychoactive compound in cannabis, activates cannabinoid receptors in ways that trigger a cascade of harmful effects. It promotes oxidative stress—essentially, it causes cells to rust from the inside out. It sparks inflammation in blood vessel walls, the first step in atherosclerosis. It interferes with how the heart contracts, reducing its pumping efficiency.

Cannabis also wreaks havoc on the autonomic nervous system, which regulates heart rate and blood pressure. Within minutes of use, heart rate can spike dramatically while blood pressure swings unpredictably. This combination forces the heart to work harder precisely when blood flow may be compromised—a perfect storm for triggering a cardiac event.

Research has documented that the risk of heart attack peaks within the first hour after cannabis use, suggesting an acute trigger effect similar to other major cardiac stressors.

The Stroke Connection You Need to Know

Whilst heart attacks dominate headlines, the cannabis stroke risk deserves equal attention. The same 2025 research found that younger adults who used cannabis had significantly elevated stroke risk, even without traditional risk factors like high blood pressure or tobacco use.

Cannabis appears to affect stroke risk through multiple mechanisms. It can cause blood vessels in the brain to constrict abnormally. It promotes blood clotting. It triggers inflammatory responses in vessel walls. The combination creates dangerous conditions for both ischaemic strokes (caused by blocked blood flow) and potentially haemorrhagic strokes (caused by bleeding).

For young people who believe strokes only affect the elderly, this represents a profound wake-up call. The research demonstrates that cannabis use fundamentally alters cerebrovascular function in ways that put users at immediate risk.

200 Million People Can’t Be Wrong

A meta-analysis examining 24 studies involving approximately 200 million people confirmed what individual studies suggested. Published in the journal Heart, this systematic review found that cannabis users faced a 29% higher risk of acute coronary syndrome, a 20% higher risk of stroke, and. Most alarming, a doubled risk of dying from cardiovascular disease.

These aren’t isolated findings from a single laboratory or region. The research spans multiple countries, diverse populations, and various study designs. Ten studies were conducted in the United States, with additional research from Canada and India. Seven found significant positive associations between cannabis and heart attacks, whilst the pooled data conclusively demonstrated a 50% increased risk.

The consistency across this research is striking. When hundreds of millions of data points from independent studies all point in the same direction, it becomes impossible to dismiss the connection as coincidence.

Vaping and Edibles Won’t Save You

Some advocates have suggested that smoking cannabis specifically poses risks, but that other consumption methods might be safer. The evidence doesn’t support this comforting narrative.

Studies examining cannabis use found elevated cardiovascular risks whether people smoked, vaped, or consumed edibles. Whilst smoking introduces additional particulate matter that damages blood vessels, the fundamental problem lies with THC itself and how it interacts with the cardiovascular system.

Cannabis smoke does contain many of the same toxic compounds as tobacco smoke—particulate matter, oxidant gases, carbon monoxide. These substances activate platelets, promote oxidised cholesterol formation, and trigger inflammatory responses. But even when researchers isolated cannabis users who had never smoked anything, the cardiovascular risks remained significantly elevated.

K2 and Spice: Even More Dangerous

If traditional cannabis poses substantial cardiovascular risks, synthetic cannabinoids represent an exponentially greater danger. Products marketed as K2, Spice, and similar brands contain compounds that are full agonists of cannabinoid receptors—meaning they activate these receptors completely, unlike THC which only partially activates them.

These synthetic substances can be hundreds of times more potent than natural cannabis. They’ve been linked to severe cardiac emergencies including sudden cardiac arrest from dangerous heart rhythm abnormalities, acute heart attacks in otherwise healthy young people, and catastrophic strokes.

Critically, standard drug tests don’t detect synthetic cannabinoids, making it difficult for medical professionals to identify exposure when users present with cardiac emergencies.

Why Doctors Are Sounding the Alarm

As cannabis legalisation expands globally and social attitudes shift towards acceptance, consumption rates have climbed, particularly among younger demographics. The 2025 research reveals that this trend coincides with cardiovascular risks that public health messaging has largely failed to communicate. Understanding cannabis and heart attack risk has become critical for anyone making informed decisions about their health.

The researchers behind these studies have called for cannabis to be treated as a serious cardiovascular risk factor, on par with tobacco smoking, hypertension, and high cholesterol. Dr Ibrahim Kamel, lead author of the landmark 2025 study, stated: “At a policy level, a fair warning should be made so that people who are consuming cannabis know that there are risks.”

Yet public perception lags dangerously behind the science. Legalisation and medical cannabis programmes have inadvertently fostered the belief that cannabis is benign. The cardiovascular research tells a different story entirely.

Is Any Amount Safe? Cannabis and Heart Attack Risk

The dose-dependent relationship observed in multiple studies, where more frequent use correlates with higher cardiovascular risk, suggests there’s no threshold where cannabis and heart attack risk disappears entirely. Daily users face the highest risks, but even occasional use shows elevated cardiovascular danger compared to abstinence.

This presents a clear message: from a cardiovascular standpoint, any cannabis use carries risk. For young people who believe they’re invulnerable, for individuals with undiagnosed heart conditions, for anyone with a family history of cardiovascular disease, that risk could prove fatal.

Where You Stand on the Risk Scale

Cardiovascular disease remains the leading cause of death globally. The addition of cannabis as a significant, modifiable risk factor changes the prevention landscape fundamentally.

Traditional risk factors. Smoking, obesity, sedentary lifestyle, poor diet, hypertension: remain critical. But the emerging evidence demonstrates that cannabis use independently elevates risk, potentially turning someone who would otherwise be safe into someone vulnerable to life-threatening cardiac events.

The research indicates that asking about cannabis use should become standard practice in cardiovascular risk assessment, alongside questions about tobacco, exercise, and family history. For individuals making informed decisions about their health, this information is essential.

Major Medical Organisations Agree

The scientific consensus emerging from this research is unambiguous. Major cardiovascular organisations including the American Heart Association and the American College of Cardiology have published statements acknowledging the cardiovascular risks of cannabis use.

Editorials accompanying the research have called for cannabis to be actively discouraged from a public health standpoint, with particular protection for vulnerable populations. The comparison to tobacco is deliberate. Both substances carry serious cardiovascular risks that public policy should address.

Researchers emphasise the need for continued investigation into mechanisms, dose-response relationships, and population-specific vulnerabilities. But the foundation of evidence is already substantial enough to warrant serious concern and immediate public health action.

The Bottom Line on Cannabis and Your Heart

This body of research represents a turning point in our understanding of cannabis and cardiovascular health. The evidence is no longer preliminary, isolated, or ambiguous. Multiple large-scale studies involving millions of participants have demonstrated clear, consistent, and alarming associations between cannabis use and serious heart disease.

For individuals, the message is straightforward: cannabis use significantly elevates the risk of heart attack, stroke, heart failure, and cardiovascular death. This risk exists independently of other factors, affects young people who should be at low cardiovascular risk, and increases with frequency of use.

The choice to use cannabis is ultimately personal, but it should be an informed choice based on accurate understanding of genuine risks. The research published in 2024 and 2025 provides that information with unprecedented clarity.

Hearts are remarkable organs, resilient and powerful. But they’re not invincible, and the evidence demonstrates that cannabis use represents a serious, preventable threat to cardiovascular health. In an era where heart disease remains our greatest health challenge, adding unnecessary risk factors makes little sense.

The conversation around cannabis has focused heavily on legalisation, medical applications, and social justice. It’s past time the discussion included the cardiovascular consequences that research has now conclusively documented.

Your heart deserves better than wishful thinking and outdated assumptions. It deserves decisions based on the best available science. And that science speaks clearly about the dangers cannabis poses to cardiovascular health.

References

1. Kamel I, Mahmoud AK, Twayana AR, et al. Myocardial Infarction and Cardiovascular Risks Associated with Cannabis Use: A Multicenter Retrospective Study. JACC Adv. 2025. https://www.acc.org/About-ACC/Press-Releases/2025/03/17/15/35/Cannabis-Users-Face-Substantially-Higher-Risk
2. Jeffers AM, Glantz S, Byers AL, Keyhani S. Association of Cannabis Use With Cardiovascular Outcomes Among US Adults. J Am Heart Assoc. 2024;13(5):e030178. https://www.ahajournals.org/doi/10.1161/JAHA.123.030178
3. Cardiovascular risk associated with the use of cannabis and cannabinoids: a systematic review and meta-analysis. Heart. 2024. https://bmjgroup.com/cannabis-use-linked-to-doubling-in-risk-of-cardiovascular-disease-death/
4. Chandy M, Jimenez-Tellez N, Wu JC. The relationship between cannabis and cardiovascular disease: clearing the haze. Nat Rev Cardiol. 2025;22:467-481. https://www.nature.com/articles/s41569-025-01121-6

"For patients using cannabis or cannabinoids for treatment of medical conditions, clinicians should discuss harm reduction strategies, including avoiding concurrent use with alcohol or other central nervous system depressants such as benzodiazepines, using the lowest effective dose, and avoiding use when driving or operating machinery.

Evidence from randomized clinical trials does not support the use of cannabis or cannabinoids for mostconditions for which it is promoted, such as acute pain and insomnia.“

 (For complete analysis https://pubmed.ncbi.nlm.nih.gov/41296368/) 

A groundbreaking study from the University of California San Diego has identified cannabis as a significant gateway to tobacco use among American youth and young adults. The research reveals that cannabis may be responsible for roughly 13% of new regular tobacco cases in the United States.

The study, published in the journal Tobacco Control, challenges traditional assumptions about the relationship between cannabis and tobacco amongst young people. It provides compelling evidence that cannabis serves as a gateway to tobacco addiction rather than the reverse.

Understanding the Cannabis Gateway to Tobacco Research

Researchers analysed national data from more than 13,800 respondents between the ages of 12 and 24 who had not previously been regular tobacco users. The data came from the Population Assessment of Tobacco and Health (PATH) study conducted in 2017.

Among those surveyed, 15% reported using cannabis within the previous year. Four years later, in 2021, cannabis users were significantly more likely to have taken up regular tobacco use compared to non-users.

“This study challenges long-held assumptions about the pathways between cannabis and tobacco use amongst youth,” said corresponding study author Karen Messer, PhD, professor at the UC San Diego Herbert Wertheim School of Public Health and Human Longevity Science.

The observational study tracked participants over four years to examine progression patterns. Researchers used propensity score matching to control for confounding factors including demographics, tobacco use history, perceived harmfulness of cigarettes, and mental health symptoms.

Striking Differences Between Age Groups

Among younger respondents aged 12 to 17, 32.7% of those who used cannabis had become regular tobacco users by 2021. This represented approximately 15 percentage points higher than their peers who did not use cannabis.

The cannabis gateway to tobacco effect proved particularly pronounced in this age group. Among youth who had never used tobacco at baseline, 24.0% of cannabis users reported current regular tobacco use four years later, compared with just 7.5% of matched controls who did not use cannabis.

Among youth who had experimented with but never regularly used tobacco, 36.8% of cannabis users progressed to regular tobacco use. This compared to 22.9% of their matched peers who did not use cannabis.

For young adults aged 18 to 24, the difference was smaller but still notable. Overall, 14% of cannabis users in this age group became regular tobacco users, representing a 5.4 percentage point increase over their matched controls.

National Impact of Cannabis as Gateway to Tobacco

When weighted on a national level, researchers estimate that more than 509,800 fewer young Americans might have avoided regular tobacco use in 2021 if they had not previously used cannabis.

The study attributed 13.0% of total new regular tobacco use in the United States to cannabis. This represents a substantial proportion of new cases amongst a population where tobacco use has historically declined.

Among the estimated 1.96 million never regular tobacco users aged 12 to 17 who used cannabis in 2017, 33.8% progressed to current regular tobacco use by 2021. The matched analysis estimates these numbers would have been reduced by 43.6% in the absence of cannabis.

Among 4.69 million never regular tobacco user young adults who used cannabis, 14.4% progressed to current regular tobacco use. These numbers would have been reduced by 32.6% without cannabis use.

The “Reverse Gateway” Phenomenon

The findings support an emerging “reverse gateway” effect, suggesting that using cannabis may lead to initiation of other addictive substances like tobacco. This challenges the traditional “gateway hypothesis” from the 1970s, which noted that adolescent cannabis users had almost all started by first smoking tobacco.

Public health action against tobacco led to dramatic declines in cigarette smoking amongst US youth. However, cannabis use did not decline in the same way. By 2005, 50% of US high school seniors had ever used tobacco, and 45% had ever used cannabis.

Cigarette smoking is now at historically low levels amongst American youth. However, electronic nicotine delivery systems (ENDS) have become the most popular tobacco product. Ever-use of any tobacco product has remained comparatively stable amongst US high school students at 23.4% in 2024.

Cannabis use has also remained stable, at 47% amongst US high school students in 2024. This rate is higher than tobacco use rates.

Shared Risk Factors and Common Liabilities

Cannabis and tobacco share many common risk factors in this cohort. These included prior experimentation with tobacco products, living with a smoker in the home, reported mental health symptoms, and residence in certain US regions.

Common liabilities for initiation of both substances include individual factors such as anxiety, depression, conduct disorder, and attention-deficit/hyperactivity disorder. Environmental factors include stress, drug use modelling in the family, social norms of friendship groups, and easy access to products.

Twin studies have identified overlapping genetic influences in cannabis and tobacco use. These include genes influencing dopamine signalling and genetic factors predisposing people to impulsivity and risk-taking.

The study found that past-hour substance use was the strongest indicator that someone would use the next day. Situational risk factors, such as seeing drugs or being near substances, also strongly predicted use.

Implications for Prevention Efforts

“These findings underscore the importance of investigating not only the direct effects of cannabis, but also its broader influence on patterns of tobacco initiation and dependence,” Messer explained.

The finding that prior cannabis use is a major risk factor for initiation of current regular tobacco use amongst youth suggests important policy implications. The effect occurs independent of whether young people have tried tobacco, indicating cannabis represents a primary risk factor.

The research suggests that tobacco control programmes should include cannabis prevention as a key goal. Successful teenage tobacco control activities have shown spillover effects in reducing teenage cannabis use in some instances.

However, although major health agencies recognise early cannabis use as a significant public health problem, they have not adequately addressed its potential to increase future regular tobacco use.

Study Methodology and Strength

The study centred on 13,851 respondents aged 12 to 24 years who had never or never regularly used tobacco in 2017. All participants completed follow-up surveys in 2019 and 2021.

Researchers used propensity score matching to create comparable groups. The researchers matched each cannabis user with up to two similar non-users based on demographics, tobacco use history, perceived cigarette harm, mental health symptoms, and other baseline measures.

Most cannabis users (93%) were successfully matched. After matching, the exposure groups were well balanced on all confounders, strengthening the validity of the comparisons.

The comprehensive list of baseline covariates helped control for confounding. Survey weights adjusted for sampling design, longitudinal dropout, and non-response to ensure estimates represented the civilian non-institutionalised US population.

Study Limitations Acknowledged

Researchers noted that the observational study does not prove that cannabis directly causes tobacco use. It demonstrates a strong association whilst controlling for known confounding factors.

Additional factors such as peer influences, socioeconomic status, and general susceptibility to substance use were not fully accounted for and could play a role. Cannabis use may in part be a marker for these underlying factors rather than solely a cause of increased tobacco use.

The study used self-reported measures of tobacco and cannabis use, though such measures have been validated with biomarkers. Attrition and non-response in longitudinal surveys present challenges, though survey weights help mitigate these issues.

The exposure measure of “past 12 months” cannabis use is likely to underestimate effect sizes compared to a more proximal measure such as current cannabis use. This suggests the true association may be even stronger than reported.

Call for Integrated Prevention Strategies

The authors conclude that cannabis use amongst youth should be considered a major risk factor for later tobacco addiction. They recommend that prevention efforts should address both substances together.

Cannabis prevention should be incorporated as a synergistic strategy within tobacco control programmes. Regulatory approaches, school-based interventions, and targeted public health messaging campaigns should address both substances.

The study provides evidence that failure to address cannabis use amongst young people has potential to undermine progress tobacco control efforts have made in reducing tobacco initiation and progression to regular use.

Strategies for integrating the understanding of cannabis as a gateway to tobacco into prevention programmes should be considered urgently. The identification of high-risk groups, the estimated impact of reducing risk factors, and the relative contribution to overall cases all support cost-effective intervention approaches.

The research was funded in part by the Tobacco-Related Disease Research Programme of the University of California and the National Cancer Institute. It represents an important contribution to understanding substance use patterns amongst young people. (Source: WRD News)

JAMA Network: Open Published Online 2025;8;(1):e2457069. doi:10.1001/jamanetworkopen.2024.57069

Key Points

Question  Are recent cannabis use and lifetime cannabis use associated with differences in brain function during cognitive tasks?

Findings  In this cross-sectional study of 1003 young adults, heavy lifetime cannabis use was associated with lower brain activation during a working memory task; this association remained after removing individuals with recent cannabis use. These results were not explained by differences in demographic variables, age at first cannabis use, alcohol use, or nicotine use.

Meaning  These findings suggest that cannabis use is associated with short- and long-term brain function outcomes, especially during working memory tasks.

Abstract

Importance  Cannabis use has increased globally, but its effects on brain function are not fully known, highlighting the need to better determine recent and long-term brain activation outcomes of cannabis use.

Objective  To examine the association of lifetime history of heavy cannabis use and recent cannabis use with brain activation across a range of brain functions in a large sample of young adults in the US.

Design, Setting, and Participants  This cross-sectional study used data (2017 release) from the Human Connectome Project (collected between August 2012 and 2015). Young adults (aged 22-36 years) with magnetic resonance imaging (MRI), urine toxicology, and cannabis use data were included in the analysis. Data were analyzed from January 31 to July 30, 2024.

Exposures  History of heavy cannabis use was assessed using the Semi-Structured Assessment for the Genetics of Alcoholism, with variables for lifetime history and diagnosis of cannabis dependence. Individuals were grouped as heavy lifetime cannabis users if they had greater than 1000 uses, as moderate users if they had 10 to 999 uses, and as nonusers if they had fewer than 10 uses. Participants provided urine samples on the day of scanning to assess recent use. Diagnosis of cannabis dependence (per Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria) was also included.

Main Outcomes and Measures  Brain activation was assessed during each of the 7 tasks administered during the functional MRI session (working memory, reward, emotion, language, motor, relational assessment, and theory of mind). Mean activation from regions associated with the primary contrast for each task was used. The primary analysis was a linear mixed-effects regression model (one model per task) examining the association of lifetime cannabis and recent cannabis use on the mean brain activation value.

Results  The sample comprised 1003 adults (mean [SD] age, 28.7 [3.7] years; 470 men [46.9%] and 533 women [53.1%]). A total of 63 participants were Asian (6.3%), 137 were Black (13.7%), and 762 were White (76.0%). For lifetime history criteria, 88 participants (8.8%) were classified as heavy cannabis users, 179 (17.8%) as moderate users, and 736 (73.4%) as nonusers. Heavy lifetime use (Cohen d = −0.28 [95% CI, −0.50 to −0.06]; false discovery rate corrected P = .02) was associated with lower activation on the working memory task. Regions associated with a history of heavy use included the anterior insula, medial prefrontal cortex, and dorsolateral prefrontal cortex. Recent cannabis use was associated with poorer performance and lower brain activation in the working memory and motor tasks, but the associations between recent use and brain activation did not survive false discovery rate correction. No other tasks were associated with lifetime history of heavy use, recent use, or dependence diagnosis.

Conclusions and Relevance  In this study of young adults, lifetime history of heavy cannabis use was associated with lower brain activation during a working memory task. These findings identify negative outcomes associated with heavy lifetime cannabis use and working memory in healthy young adults that may be long lasting. 

(For complete Research: JAMA Network)

There is abundant scientific literature on the harms of marijuana use that will be discussed in this report. More than 20,000 peer-reviewed research articles have linked marijuana use to adverse mental health outcomes, ranging from depression to psychosis, as well as consequences for physical health and even negative outcomes for neonates exposed in utero. The connections between marijuana use and negative consequences for mental and physical health, among other risks, are often 2 3 lost in the debate surrounding legalization. The distinction between medical and recreational marijuana has been deliberately blurred by an industry with significant investments in both markets. A study found that despite evidence that lower THC dosage is more appropriate for medical purposes, the medical marijuana products that are advertised in retail stores contain around the same amount of THC as recreational marijuana products, which generally contain upwards of 15% THC (Cash et al., 2020). And a 2022 study suggests that the risk of developing a cannabis use disorder (CUD) increases as marijuana’s THC level increases (Petrilli et al., 2022).

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