The Scale of Harm: Alcohol Scores 79/100, Cannabis 15/100
How the Multi-Criteria Decision Analysis framework ranks substances — and why alcohol is the most destructive substance known to humanity.
In 2010, a team led by Professor David Nutt published a landmark study in The Lancet that would forever change how scientists think about drug harm. Using a framework called Multi-Criteria Decision Analysis (MCDA), the researchers asked a simple question: if we judge drugs not by legal classification but by objective measures of harm — to the user, to others, and to society — how do they truly compare? [Nutt et al. (2010, The Lancet)]
The answer was explosive. Alcohol scored 79 out of 100 — the highest of any substance, surpassing heroin (55), crack cocaine (54), and methamphetamine (33). Cannabis scored just 15. The legal status of these substances bore almost no relation to their scientific harm profile. Alcohol, the most harmful drug overall, was legal and aggressively marketed. Cannabis, among the least harmful, carried criminal penalties. [Journal of Psychopharmacology (2026, CIHR-funded)]
The MCDA framework evaluates drugs across 16 criteria, divided into harm to the user (drug-specific mortality, drug-related mortality, drug-specific damage, dependence, impairment, loss of tangibles, loss of relationships) and harm to others (injury, crime, family adversity, community decline, economic cost, environmental damage, and international damage). Each criterion is weighted by expert panels, producing a composite score that reflects the totality of harm. [Nutt et al. (2010, The Lancet)]
In 2026, the MCDA framework was updated with new data from the Canadian Institutes of Health Research. The updated ranking confirmed the original findings: alcohol remains the most destructive substance, while cannabis remains near the bottom. The gap between scientific evidence and legal policy is as wide as ever. [Journal of Psychopharmacology (2026)]
For a side-by-side comparison of all 18 substances across every harm criterion, visit our full Substance Matrix. To see how alcohol and cannabis compare on specific harm dimensions, explore the Harm Matrix.
Sources: [Nutt et al. (2010, The Lancet)] | [Journal of Psychopharmacology (2026)] | [Canadian Institutes for Health Research]