Impact of partial cannabis legalisation in Luxembourg: an interdisciplinary perspective

Background In 2023, Luxembourg partially legalised cannabis, permitting home cultivation and private-domain use. The current study aimed to evaluate the short-term impacts of this reform on consumption patterns, market dynamics, product potency, and cannabis-related driving-under-the-influence cases (DUI). Methods An interdisciplinary approach was applied, combining data from cannabis seizures, wastewater analysis, toxicological data from DUI cases, and a web-based consumer survey. Indicators were compared before and after the policy change. Results Most indicators suggested a limited overall impact of partial legalisation in the year following the reform. Tetrahydrocannabinol (THC) concentrations in seized herbal and resin samples remained stable, as did THC metabolite loads in wastewater. Consumer surveys indicated little change in user patterns, prices, or acquisition channels, with most users continuing to purchase from illicit sources. Only a minority of respondents reported personal or intended future cultivation. In contrast, cannabis-related DUI cases increased significantly. Although average THC concentrations in blood samples remained unchanged, elevated levels of THC metabolites suggested a potential increase in chronic use among some individuals. Conclusion Partial cannabis legalisation in Luxembourg appears to have had only moderate impacts on market dynamics, consumer patterns, and product potency during the first year, but was associated with an increase in cannabis-related DUI cases. Similar to findings in other countries, new initiation of cannabis consumption was limited, while existing frequent users may have intensified their use. These findings highlight the need for continued monitoring of impaired driving, cannabis user patterns, and emerging trends in self-cultivation, alongside public education on health risks.