<p>Infrared thermography in biomedical and health-related research has expanded across multiple clinical and methodological applications, yet its global structure has remained insufficiently characterised. This study provides a longitudinal scientometric analysis of a deduplicated Scopus-Web of Science corpus covering 1980–2025. The workflow integrated publication output, field- and year-normalised citation impact, international collaboration, citation inequality, and keyword-based thematic mapping. The corpus contained 12,255 unique documents, of which 12,246 fell within the 1980–2025 analytical window. Results showed a field that is internationally connected but unevenly scaled. High-income countries dominated publication volume and total citations, whereas differences in normalised impact across income groups were less clear-cut once field and year were controlled. Citation totals were strongly concentrated within income strata under both full and fractional counting. The collaboration network displayed a dense central backbone anchored by a limited set of highly connected countries. Thematic analysis identified a small number of dominant programmes alongside a long tail of micro-topics. Over time, the field diversified away from foundational skin-temperature thermography, with diagnostic imaging, breast cancer, and artificial intelligence emerging as the clearest recent hotspot within the human-health core, while some expanding themes reflected boundary-spanning literatures captured by the broad retrieval strategy. Within the retrieved corpus, infrared thermography appears as a maturing interdisciplinary domain characterised by thematic differentiation, broad journal dispersion, stable international collaboration, and persistent inequalities in participation scale and citation concentration.</p>