There’s no single number that tells you how many years cannabis smoking takes off your life. Unlike tobacco, where decades of research have pinpointed an average loss of about 10 years, cannabis research is still catching up. What we do know is that regular cannabis use is linked to a meaningfully higher risk of early death, with the strongest evidence pointing to a 53% greater risk of dying from any cause compared to non-users, based on a recent meta-analysis of cohort studies. But that number comes with important caveats about who’s using, how much, and what else they’re doing.
What the Mortality Data Actually Shows
A 2025 systematic review pooling data from multiple long-term studies found that cannabis users had a relative risk of 1.53 for all-cause mortality compared to people who never used. That means, across the studies analyzed, users were about 53% more likely to die during the follow-up period than non-users. When researchers looked only at high-quality prospective studies (which track people forward in time rather than looking backward), the risk was even higher, roughly double that of non-users.
Separately, among people diagnosed with cannabis use disorder who received hospital-based care, 3.5% died within five years. That’s six times the rate of the general population over the same period. Even after adjusting for other substance use, mental health conditions, and chronic illness, the risk of death remained 2.8 times higher. For context, cannabis use disorder carries about half the five-year mortality risk of opioid use disorder and slightly less than alcohol use disorder.
How Frequency Changes the Risk
The more often you use cannabis, the steeper the health risks become, and the pattern is consistent across studies. Daily cannabis users have a 25% increased likelihood of heart attack and a 42% increased likelihood of stroke compared to non-users. Weekly users show smaller but still measurable increases: about 3% for heart attack and 5% for stroke.
Heart disease risk specifically follows a dose-response curve. In a nationally representative U.S. survey of adults under 50, every additional 90 days of cannabis use per year was associated with 9% higher odds of heart disease. Daily users had 40% higher odds compared to non-users. This is notable because heart disease among younger adults is relatively uncommon, so a 40% increase in a low-probability event isn’t the same as a 40% increase in a common one. Still, the linear relationship between frequency and risk is clear.
Lung Damage From Smoking Cannabis
Smoking is smoking, regardless of what’s burning. A study using chest CT scans found that 75% of cannabis smokers had emphysema, compared to 67% of tobacco-only smokers and far fewer non-smokers. Cannabis smokers were especially prone to a specific type of emphysema that damages the tiny ducts connecting to the air sacs in the lungs.
Airway inflammation and chronic bronchitis were also more common in cannabis smokers than in both non-smokers and tobacco-only smokers. Researchers noted that cannabis appears to have effects on the lungs beyond what tobacco alone causes, suggesting the two substances together are worse than either one individually. This matters because a large percentage of cannabis smokers also use tobacco, making it hard to separate the damage from each.
The Tobacco Problem in Cannabis Research
One of the biggest challenges in studying cannabis and life expectancy is that many cannabis users also smoke tobacco, drink heavily, or use other substances. When researchers try to untangle these factors, the picture shifts considerably.
A large study published in JAMA Network Open looked at heavy cannabis use and mortality separately by sex, adjusting for tobacco history, alcohol, blood pressure, diabetes, and other conditions. Among women who also smoked tobacco, heavy cannabis use more than doubled the risk of death from any cause and tripled the risk of cancer death. But when the researchers excluded anyone with hypertension, diabetes, obesity, current tobacco use, or prior cardiovascular disease, heavy cannabis use was no longer significantly associated with dying from any cause, cancer, or heart disease in either men or women.
Similarly, when looking at cannabis users versus never-users without accounting for how heavily they used, there was no significant increase in death from any cause, heart disease, or cancer for either sex. This suggests that much of the mortality risk attributed to cannabis may be driven by the heaviest users and by the overlap with tobacco and other health conditions. It does not mean cannabis is harmless. It means the risk is concentrated in certain patterns of use.
Faster Biological Aging
Even if cannabis doesn’t kill you outright, it may age you faster. The Dunedin Study, which has tracked over 1,000 people born in New Zealand in 1972-73 from birth through age 45, found that long-term cannabis users showed significantly accelerated biological aging. Researchers measured this using pace of aging, brain scans, walking speed, and how old participants looked compared to their actual age. The differences were large and statistically robust.
Long-term users also scored worse on measures of health preparedness (less knowledge about their health, more pessimism about aging, shorter self-predicted life expectancy), financial preparedness (less savings, lower credit scores, more financial problems), and social preparedness (more loneliness, less social support, lower life satisfaction). The relationship followed a dose-response pattern: the more times someone had been diagnosed with cannabis dependence between ages 18 and 45, the worse their outcomes at midlife.
Mental Health and Suicide Risk
Cannabis is the most commonly detected illicit substance in the toxicology tests of suicide victims. Heavy cannabis use is associated with roughly 2.5 times the odds of suicidal thoughts and 3.2 times the odds of a suicide attempt compared to non-use. Starting young, using for many years, and consuming heavily all correlate with worse outcomes. Among people with cannabis use disorder specifically, suicide is one of the leading causes of death, followed by opioid poisoning, other drug poisonings, trauma, and lung cancer.
Cognitive Decline May Not Be the Concern You Think
One area where cannabis research is more reassuring than expected is long-term cognitive decline. A Danish study following more than 5,000 men for an average of 44 years found no significant harmful effects of cannabis use on age-related cognitive decline from early adulthood to late midlife. Men who had used cannabis actually showed slightly less cognitive decline than non-users, though this likely reflects other differences between the groups rather than a protective effect of cannabis. Neither the age someone started using nor how frequently they used was linked to greater mental sharpness loss over time.
What This Means in Practical Terms
No study has produced a clean number like “cannabis smokers live X fewer years.” The research consistently shows that heavy, long-term cannabis smoking is associated with higher risks of heart attack, stroke, lung disease, certain cancers (particularly in women who also smoke tobacco), suicide, and faster biological aging. Occasional use carries much smaller, sometimes statistically insignificant risks. The method of consumption matters too: most of the lung damage research is specific to smoking, and nearly all the large mortality studies involve smoked cannabis rather than edibles or other forms, making it difficult to draw conclusions about non-smoked consumption.
The clearest takeaway is that the risks scale with use. Daily smoking over many years is a fundamentally different exposure than occasional use, and the health consequences reflect that. People who smoke cannabis daily, especially those who also use tobacco, carry the most concentrated risk for shortened life expectancy.