Evaluating the carbon footprint of antibiotics prescribed in Irish primary care: a retrospective analysis using the medicine carbon footprint (MCF) method

Abstract Introduction Climate change is one of the most urgent global health challenges, with healthcare contributing around 5% of global greenhouse gas emissions. Medicines are estimated to represent 20–55% of healthcare’s carbon footprint, yet their environmental impact is poorly characterised.[1] Antibiotics are among the most frequently prescribed medicines, making them a major contributor to antimicrobial resistance and healthcare-associated carbon emissions.[2] To date, no study has quantified the carbon footprint of antibiotics in Ireland, representing an evidence gap with important policy implications. Aim The primary aim of this study was to evaluate the carbon footprint of antibiotics prescribed in Irish primary care between 2019 and 2024 using the MCF method. Methods Prescription data were obtained from the Health Service Executive–Primary Care Reimbursement Service for antibiotics dispensed between 2019 and 2024. Only agents with available MCF ratings were included. The MCF method estimates the greenhouse gas emissions associated with the production of active pharmaceutical ingredients per dose, classifying medicines as low (<10gCO2e), medium (10–100gCO2e), high (100–1000gCO2e), or very high (>1000gCO2e). Prescription volumes were combined with MCF ratings and Ireland’s Green/Red Antibiotic Quality Improvement initiative, which classifies antibiotics as ‘green’ (preferred) or ‘red’ (not preferred) to support prudent antimicrobial prescribing, to estimate trends in carbon footprint. Results Table 1 summarises annual prescription volumes and corresponding MCF ratings for all included antibiotics. Of 23 antibiotics analysed, 21 were categorised as having a high or very high carbon footprint. Antibiotic prescriptions increased annually, with amoxicillin use more than doubling from 2020 to 2024. Red-listed antibiotics had a higher carbon footprint than green-listed agents, with 73% of red-listed prescriptions falling in the very high carbon category versus 1% of green-listed prescriptions. Conclusion Findings highlight that most prescribed antibiotics have a high/very high environmental impact. The MCF Formulary offers a practical tool to inform prescribers how they can implement carbon-conscious prescribing by allowing an appreciation of the environmental impact of prescribing choices. Despite this, limitations include exclusion of combination products and extrapolation of 2024 data. Integrating environmental sustainability into antimicrobial stewardship initiatives could synergistically reduce antimicrobial resistance whilst supporting climate goals.