Unused medications negatively impact the environment and healthcare budgets. To meet Green Deal goals, a healthcare system-wide assessment of unused medications could yield a comprehensive basis for promoting sustainable medication practices. This study aimed to quantify unused medications across the Dutch healthcare system, including its carbon footprint and economic impact.

This cross-sectional study was conducted in eleven community pharmacies, three outpatient pharmacies, 22 hospital departments, and 17 tertiary care departments in the Netherlands. Unused medications were collected during two weeks. Primary outcome was quantity of unused medication in Defined Daily Doses (DDDs). Secondary outcomes included waste-based carbon emissions, based on weight of unused medications, and economic value, determined using Dutch retail prices.

In community and outpatient pharmacies, respectively, 148 and 47 DDDs per 100 dispensed orders remained unused. In hospital and tertiary care departments, respectively, 243 and 245 DDDs per 100 occupied beds per day remained unused. Waste-based carbon emissions in community and outpatient pharmacies were, respectively, 0.32 and 0.24 kgCO2-equivalent per 100 dispensed orders. In hospital and tertiary care departments, respectively, 3.58 and 0.69 kgCO2-equivalent per 100 occupied beds per day was emitted. The economic loss was €89 and €249 per 100 dispensed orders in community and outpatient pharmacies, respectively, and €359 and €121 per 100 occupied beds in hospital and tertiary care departments.

Medications remain unused across all healthcare settings, resulting in carbon emissions and economic losses. Implementing strategies to reduce unused medication could mitigate environmental contamination that threatens human health, while enhancing economic sustainability of healthcare systems.