Cannabis and synthetic cannabinoids have been linked to strokes in young adults | Research

The takeaway

A review of 98 reported cases found that cannabinoid-related strokes primarily affected young men who were chronic users, though strokes remain rare relative to overall cannabis use.

Read this if you use cannabis regularly and want to understand the rare but real vascular risks, especially if you are young.

98 cases of cannabinoid-related stroke in the literature, average age 32

What the researchers found

Researchers compiled 98 cases from the medical literature where stroke occurred in the context of cannabinoid use. Of these, 85 followed natural cannabis use and 13 followed synthetic cannabinoid use. The average age was just 32 years old, and men were nearly four times more likely to be affected than women.

The vast majority of cases (85 of 98) involved ischemic strokes, where blood flow to the brain is blocked, rather than hemorrhagic strokes involving bleeding. Most patients (81%) were chronic cannabis users, and 18% had recently increased their consumption shortly before the stroke occurred.

While 46% of patients recovered with no or few lasting effects, five people died following their strokes. A proposed mechanism in about 27% of cases was reversible cerebral vasoconstriction, where blood vessels in the brain suddenly narrow. The authors suggest some individuals may have a genetic predisposition that makes them more vulnerable to this vascular toxicity.

Why it matters

While cannabinoid-associated strokes appear to be rare compared to the large number of people who use cannabis worldwide, the fact that they disproportionately affect young adults is concerning. Young people typically have very low stroke risk, and any factor that increases it warrants attention. The review also highlights that these cases may be underreported because clinicians do not always ask about or test for cannabis use in stroke patients.

The numbers in context

98 total cases identified in the literature. 85 involved natural cannabis, 13 involved synthetic cannabinoids. Mean age was 32.3 years. Male-to-female ratio was 3.7 to 1. Cannabis was smoked with tobacco in 66% of cases. 81% were chronic users. 46% had favorable outcomes. 5 patients died. Reversible cerebral vasoconstriction was identified in 27% of cases.

How the study worked

This was a narrative review that compiled all published case reports and case series of cannabinoid-associated strokes from the medical literature. The authors analyzed patient demographics, type of cannabinoid used, type of stroke, clinical outcomes, and proposed mechanisms across all 98 reported cases.

What this study cannot tell us

The review is limited to published case reports, which represent a selection bias toward unusual or severe cases. There is no denominator showing how many cannabis users did not experience strokes, making it impossible to calculate actual risk rates. Tobacco co-use in 66% of cases complicates attribution. The temporal correlation between cannabis use and stroke does not establish causation, as the authors themselves acknowledge.

How to read the evidence

This is a narrative review of case reports, providing moderate evidence of an association but unable to establish causation or risk rates.

When this study was published

Published in 2017, this review covers cases reported up to that date.

The bigger picture

This review sits within a broader conversation about the cardiovascular risks of cannabis. While most public attention focuses on respiratory or mental health effects, vascular complications like stroke represent a less-discussed but potentially serious risk. The finding that synthetic cannabinoids carry similar or greater risk adds urgency, as these products are often more potent and unpredictable than natural cannabis.

Questions still open

Why do some individuals appear genetically susceptible to cannabinoid-related vascular events while most users are unaffected? Would routine drug screening in young stroke patients reveal a higher incidence than currently reported? Do synthetic cannabinoids carry proportionally greater stroke risk than natural cannabis?

Common questions

How common are cannabis-related strokes?

They appear to be rare relative to the millions of people who use cannabis worldwide. Only 98 cases were found in the entire medical literature. However, the authors believe this number is likely an undercount because cannabis use is not routinely screened in stroke patients.

Does smoking method matter for stroke risk?

The review noted that 66% of patients smoked cannabis with tobacco, which is itself a stroke risk factor. The contribution of the smoking route versus the cannabinoid compounds themselves remains unclear.

Read the original research

Strokes are possible complications of cannabinoids use.

Epilepsy & behavior : E&B, 70(Pt B), 355-363

View on PubMed ↗Publisher’s paper ↗

Citation

Wolff, Valérie; Jouanjus, Emilie. (2017). Strokes are possible complications of cannabinoids use.. Epilepsy & behavior : E&B, 70(Pt B), 355-363. https://doi.org/10.1016/j.yebeh.2017.01.031