Lay summary
All drugs, including illicit drugs, licit drugs (e.g. alcohol and tobacco), and emerging synthetic drugs (e.g. carfentanil) can cause harm. Drug policy needs to take into account the harmfulness of a drug, considering both harms to individuals and to others including families, communities, and society. Drug harm ranking studies are a robust method for systematically quantifying drug harms, however, these need to be done locally to reflect cultural and social context, and improvements to the multi-criteria decision-making (MCDA) approach have been proposed. This study will complete a drug harms ranking study for New Zealand, considering the total population, plus analysis specific to both Māori and youth. A participatory and inclusive process will be utilised to extend the MCDA methodology, to build a nuanced picture of drug harm in New Zealand. This study will contribute to drug policy reform, inform resource allocation, and guide health promotion efforts to reduce drug harms.