At the UN Climate Change Conference 26 in Glasgow, 50 countries committed to low-carbon health services, with 14 countries further committing to net-zero carbon health services by 2050. Reaching this target will require decision makers to include carbon emissions when evaluating new and existing health technologies (tests and treatments). There is currently, however, a scarcity of data on the carbon footprint of health-care interventions, nor any means for decision makers to include and consider carbon emission health-care assessments. We therefore investigated how to integrate carbon emissions calculated by environmental life cycle assessment (LCA) into health technology assessments (HTA). HTAs are extensively used in developing clinical and policy guidelines by individual public or private payers, and by government organisations. In the first section we explain the methodological differences between environmentally extended input-output and process-based LCA. The second section outlines ways in which carbon emissions calculated by LCA could be integrated with HTAs, recognising that HTAs are done in several ways by different jurisdictions. International effort and processes will be needed to ensure that robust and comprehensive carbon footprints of commonly used health-care products are freely available. The technical and implementation challenges of incorporating carbon emissions into HTAs are considerable, but not unsurmountable. Our aim is to lay foundations for meeting these challenges.