Smoking cannabis has negative effects on human health
the verdict
SUPPORTED
the evidence backs this
confidence 88/100
Substantial scientific literature, including systematic reviews and meta-analyses, supports the claim that smoking or consuming cannabis has negative effects on human health, ranging from cognitive impairment and cardiovascular risks to adverse pregnancy outcomes and increased risk of psychosis.
Evidence for · 8
Does cannabis use increase the risk of death? Systematic review of epidemiological evidence on adverse effects of cannabis use
2010 · cited by 146
Calabria et al. (2010) found evidence suggesting adverse health outcomes, such as fatal motor vehicle accidents and respiratory or brain cancers, among heavy cannabis users.
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More for · 7
Evidence on the acute and residual neurocognitive effects of cannabis use in adolescents and adults: a systematic meta-review of meta-analyses.
2022 · cited by 98
A systematic meta-review by a research group in 2022 demonstrated that acute cannabis intoxication and residual use lead to small-to-moderate neurocognitive and memory deficits.
Prenatal Cannabis Use and Neonatal Outcomes: A Systematic Review and Meta-Analysis.
2025 · cited by 20
A 2025 systematic review and meta-analysis found moderate-certainty evidence linking prenatal cannabis use to adverse neonatal outcomes like low birth weight and preterm birth.
Adverse clinical effects associated with the use of synthetic cannabinoids: A systematic review.
2025 · cited by 11
A 2025 systematic review highlighted severe clinical outcomes associated with synthetic cannabinoids, including psychosis, seizures, and cardiovascular complications.
Cardiovascular risk associated with the use of cannabis and cannabinoids: a systematic review and meta-analysis.
2025 · cited by 0
A 2025 systematic review and meta-analysis revealed positive associations between cannabis use and major adverse cardiovascular events, including acute coronary syndrome and stroke.
Balancing risks and benefits of cannabis use: umbrella review of meta-analyses of randomised controlled trials and observational studies.
2023 · cited by 0
An umbrella review from 2023 reported convincing evidence that cannabis causes psychotic symptoms, impairs cognition, increases car crash risks, and worsens outcomes in pregnancy.
Cannabinoids for Medical Use: A Systematic Review and Meta-analysis.
2015 · cited by 0
A 2015 systematic review found that cannabis and cannabinoids were associated with an increased risk of short-term adverse events such as dizziness, confusion, and hallucinations.
Association of cannabis potency with mental ill health and addiction: a systematic review.
2022 · cited by 0
A 2022 systematic review concluded that the use of higher-potency cannabis is associated with an increased risk of psychosis and cannabis use disorder.