BACKGROUND: Multi-criteria decision analysis (MCDA) has been used to quantify drug harms in the United Kingdom, the European Union, Australia, and New Zealand. This paper presents the result of an MCDA conducted in Canada, with the aim of informing Canadian drug policy and contributing to public understanding of drugs' relative harms.

METHODS: A panel composed of 20 experts from six provinces determined 16 drugs to evaluate on 16 dimensions of harm (ten representing harm to people who use the drug; six representing harm to others). At a two-day decision conference, the panel scored each drug on a scale of 0-100 for each harm criterion, then weighted the relative importance of each criterion.

RESULTS: This analysis of drug harms in Canada found that alcohol causes the most harm overall, with a cumulative weighted score of 79. It was followed by tobacco (45), nonprescription opioids (33), cocaine (19), methamphetamine (19), and cannabis (15). The finding that alcohol causes the most harm is consistent with the results of previous MCDA drug harm studies.

CONCLUSION: These harm scores express population-level harm rather than individual-level "harmfulness." They reflect not only a drug's pharmacological risk profile but also the current policy context in Canada. The high score for alcohol underscores a failure to adopt policies to address alcohol-related harms, despite the known health harms and the existence of proven policy measures. More broadly, when developing drug policies, governments should consider the harm-both individual and societal-caused by drugs and by the laws and regulations that govern them.