| Brain & mind | Impairs short-term memory, attention and learning while high | Acute | Harm | Strong | NASEM 2017 |
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| Brain & mind | Roughly 3 in 10 past-year users meet criteria for cannabis use disorder | Regular use | Harm | Strong | Hasin 2015 |
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| Brain & mind | Daily high-potency use: about 5× the odds of a psychotic disorder | Regular use | Harm | Strong | Di Forti 2019 |
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| Brain & mind | Up to 30% of schizophrenia in Danish men aged 21–30 linked to cannabis use disorder | Regular use | Harm | Moderate | Hjorthøj 2023 |
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| Brain & mind | Crash risk about 1.2–1.4× when driving high | Acute | Harm | Moderate | Rogeberg 2016 |
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| Brain & mind | Persistent use from adolescence to 45: IQ decline and smaller hippocampus, followed from birth | Regular use | Harm | Moderate | Meier 2022 |
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| Brain & mind | Ages 40–69: ever-users score slightly higher on memory tests; genetic analysis finds no causal effect on cognitive aging or dementia | Regular use | Neutral | Moderate | Ishrat 2026 |
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| Brain & mind | Better short-term sleep in people with apnea, fibromyalgia, chronic pain or MS | Medical | Benefit | Moderate | NASEM 2017 |
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| Brain & mind | Ages 22–36, over 1,000 lifetime uses: weaker working-memory brain activation (d = −0.28) | Regular use | Harm | Limited | Gowin 2025 |
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| Brain & mind | Ages 40–69: ever-users have slightly larger hippocampus, putamen and amygdala; no adjustment for education or income | Regular use | Benefit | Limited | Guha 2026 |
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| Lungs | Smoking causes chronic cough, phlegm and bronchitis episodes; these ease after quitting | Regular use | Harm | Strong | NASEM 2017 |
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| Lungs | No link found between smoking cannabis alone and lung cancer | Regular use | Neutral | Moderate | NASEM 2017 |
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| Heart | Raises heart rate within minutes of use | Acute | Harm | Strong | NASEM 2017 |
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| Heart | Daily use: 25% higher odds of heart attack and 42% higher odds of stroke, including in non-tobacco users | Regular use | Harm | Limited | Jeffers 2024 |
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| Gut | Oral cannabinoids reduce chemotherapy nausea and vomiting | Medical | Benefit | Strong | NASEM 2017 |
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| Gut | Cannabinoid hyperemesis: bouts of severe vomiting in long-term heavy users, relieved by hot showers and resolved by stopping | Regular use | Harm | Moderate | Sorensen 2017 |
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| Pregnancy | Smoking during pregnancy lowers birth weight | Regular use | Harm | Strong | NASEM 2017 |
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| Nerves & pain | CBD cut convulsive seizures by a median 39% vs 13% on placebo in Dravet syndrome | Medical | Benefit | Strong | Devinsky 2017 |
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| Nerves & pain | Modest relief of chronic pain in adults | Medical | Benefit | Strong | NASEM 2017 |
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| Nerves & pain | Less self-reported muscle spasticity in multiple sclerosis | Medical | Benefit | Strong | NASEM 2017 |
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