Cannabis increases heart rate and can cause blood pressure drops when standing, with tolerance developing rapidly to most cardiovascular effects, but poses risks for people with existing heart disease.
Read this if you use cannabis and want to understand its effects on your heart and blood vessels.
Cardiovascular tolerance develops rapidly; risks mainly for those with heart disease
What the researchers found
Cannabis and THC increased heart rate, slightly increased blood pressure when lying down, and occasionally caused marked drops in blood pressure upon standing. Cardiac output increased while peripheral vascular resistance and maximum exercise performance decreased. Tolerance to most cardiovascular effects developed rapidly with repeated use.
With continued exposure, blood pressure while lying down decreased slightly, standing blood pressure drops disappeared, blood volume increased, and heart rate slowed. These changes were consistent with reduced sympathetic and enhanced parasympathetic nervous system activity. For most young, healthy users, these effects were not associated with serious health problems. However, occasional myocardial infarction, stroke, and other adverse cardiovascular events had been reported, and smoking cannabis posed particular risks for people with existing cardiovascular disease due to increased cardiac workload, catecholamine levels, and carbon monoxide exposure.
Why it matters
This review provided a comprehensive account of how cannabis affects the cardiovascular system, distinguishing between effects in healthy young users (generally benign) and risks in people with heart disease (potentially dangerous). The description of rapid tolerance development to cardiovascular effects was clinically relevant for understanding both recreational and medical cannabis use.
The numbers in context
No specific numerical data were presented in the abstract, though the review described characteristic patterns of heart rate increase and blood pressure changes.
How the study worked
This was a narrative review of the cardiovascular pharmacology of cannabis, covering human and animal studies of acute and chronic effects, tolerance development, and clinical safety considerations. It addressed both receptor-mediated and endocannabinoid system mechanisms.
What this study cannot tell us
As a narrative review, the evidence was synthesized without systematic methodology. Most data came from studies in young, healthy subjects and may not apply to older or medically compromised populations. The mechanisms of rare but serious cardiovascular events were not fully elucidated.
How to read the evidence
This is a comprehensive narrative review by an established pharmacologist, providing moderate-level evidence through synthesis of clinical and preclinical data.
When this study was published
Published in 2002. Subsequent large studies have provided more data on cardiovascular risks, particularly in older populations.
The bigger picture
Subsequent research has confirmed and extended these findings. Large epidemiological studies have found that cannabis use may increase the risk of heart attack and stroke, particularly in older users and those with cardiovascular risk factors. The recognition of cardiovascular risks has become more prominent as cannabis use has expanded to older populations through legalization.
Questions still open
- How does the cardiovascular risk of cannabis compare to that of tobacco or alcohol? Do non-smoked routes of cannabis administration reduce cardiovascular risks? Should people with heart disease be specifically warned against cannabis use?
Common questions
Can cannabis cause a heart attack?
Does your body get used to the heart effects of cannabis?
Read the original research
Cardiovascular system effects of marijuana.
Journal of clinical pharmacology, 42(S1), 58S-63S
Citation
Jones, Reese T. (2002). Cardiovascular system effects of marijuana.. Journal of clinical pharmacology, 42(S1), 58S-63S.
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