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the claim

Smoking cannabis has negative effects on human health

the verdict
SUPPORTED
the evidence backs this
Recorded sources
8 sources for · 0 against

Counts group repeated records of the same source within each side. They do not measure evidence strength or source independence.

Is it true that smoking cannabis has negative effects on human health?

Yes. 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.

Verdict: SUPPORTED · 8 sources for, 0 against · Last checked

The analysis

The claim is specific and empirical. Multiple high-quality systematic reviews, meta-analyses, and umbrella reviews provide robust evidence that cannabis use carries various adverse health effects, including cognitive deficits, mental health risks (such as psychosis), cardiovascular events, and complications during pregnancy. No papers refute the broad claim that cannabis has negative effects on some aspects of human health, though studies note that safety profiles vary by dosage, potency, and route of administration.

Evidence for · 8
Does cannabis use increase the risk of death? Systematic review of epidemiological evidence on adverse effects of cannabis use
2010
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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CALABRIA, B., DEGENHARDT, L., HALL, W., & LYNSKEY, M. (2010). Does cannabis use increase the risk of death? Systematic review of epidemiological evidence on adverse effects of cannabis use. doi.org. https://doi.org/10.1111/j.1465-3362.2009.00149.x

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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
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.
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Dellazizzo, L., Potvin, S., Giguère, S., & Dumais, A. (2022). Evidence on the acute and residual neurocognitive effects of cannabis use in adolescents and adults: a systematic meta-review of meta-analyses.. doi.org. https://doi.org/10.1111/add.15764

Prenatal Cannabis Use and Neonatal Outcomes: A Systematic Review and Meta-Analysis.
2025
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.
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Lo, J. O., Ayers, C. K., Yeddala, S., Shaw, B., Robalino, S., Ward, R., & Kansagara, D. (2025). Prenatal Cannabis Use and Neonatal Outcomes: A Systematic Review and Meta-Analysis.. doi.org. https://doi.org/10.1001/jamapediatrics.2025.0689

Adverse clinical effects associated with the use of synthetic cannabinoids: A systematic review.
2025
A 2025 systematic review highlighted severe clinical outcomes associated with synthetic cannabinoids, including psychosis, seizures, and cardiovascular complications.
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Prete, M. M., Feitosa, G., Ribeiro, M. A., Fidalgo, T. M., & Sanchez, Z. M. (2025). Adverse clinical effects associated with the use of synthetic cannabinoids: A systematic review.. doi.org. https://doi.org/10.1016/j.drugalcdep.2025.112698

Cardiovascular risk associated with the use of cannabis and cannabinoids: a systematic review and meta-analysis.
2025
A 2025 systematic review and meta-analysis revealed positive associations between cannabis use and major adverse cardiovascular events, including acute coronary syndrome and stroke.
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Storck, W., Elbaz, M., Vindis, C., Déguilhem, A., Lapeyre-Mestre, M., & Jouanjus, E. (2025). Cardiovascular risk associated with the use of cannabis and cannabinoids: a systematic review and meta-analysis.. doi.org. https://doi.org/10.1136/heartjnl-2024-325429

Balancing risks and benefits of cannabis use: umbrella review of meta-analyses of randomised controlled trials and observational studies.
2023
An umbrella review from 2023 reported convincing evidence that cannabis causes psychotic symptoms, impairs cognition, increases car crash risks, and worsens outcomes in pregnancy.
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Solmi, M., Toffol, M. D., Kim, J. Y., Choi, M. J., Stubbs, B., Thompson, T., Firth, J., Miola, A., Croatto, G., Baggio, F., Michelon, S., Ballan, L., Gerdle, B., Monaco, F., Simonato, P., Scocco, P., Ricca, V., Castellini, G., Fornaro, M., Murru, A., Vieta, E., Fusar-Poli, P., Barbui, C., Ioannidis, J. P. A., Carvalho, A. F., Radua, J., Correll, C. U., Cortese, S., Murray, R. M., Castle, D., Shin, J. I., & Dragioti, E. (2023). Balancing risks and benefits of cannabis use: umbrella review of meta-analyses of randomised controlled trials and observational studies.. doi.org. https://doi.org/10.1136/bmj-2022-072348

Cannabinoids for Medical Use: A Systematic Review and Meta-analysis.
2015
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.
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Whiting, P. F., Wolff, R. F., Deshpande, S., Nisio, M. D., Duffy, S., Hernandez, A. V., Keurentjes, J. C., Lang, S., Misso, K., Ryder, S., Schmidlkofer, S., Westwood, M., & Kleijnen, J. (2015). Cannabinoids for Medical Use: A Systematic Review and Meta-analysis.. doi.org. https://doi.org/10.1001/jama.2015.6358

Association of cannabis potency with mental ill health and addiction: a systematic review.
2022
A 2022 systematic review concluded that the use of higher-potency cannabis is associated with an increased risk of psychosis and cannabis use disorder.
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Petrilli, K., Ofori, S., Hines, L., Taylor, G., Adams, S., & Freeman, T. P. (2022). Association of cannabis potency with mental ill health and addiction: a systematic review.. doi.org. https://doi.org/10.1016/S2215-0366(22)00161-4

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What does the evidence say?

The claim is specific and empirical. Multiple high-quality systematic reviews, meta-analyses, and umbrella reviews provide robust evidence that cannabis use carries various adverse health effects, including cognitive deficits, mental health risks (such as psychosis), cardiovascular events, and complications during pregnancy. No papers refute the broad claim that cannabis has negative effects on some aspects of human health, though studies note that safety profiles vary by dosage, potency, and route of administration.

Receipt History
first checked31 Jul 2026
judged → SUPPORTED · 8831 Jul 2026
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