Traditional Antipyretic Medicinal Plants Used in Yasothon Province, Northeastern Thailand.

Fever is one of the most common health conditions traditionally treated with medicinal plants in rural communities, yet comprehensive documentation of antipyretic ethnomedicinal knowledge in northeastern Thailand remains limited. This study presents a focused ethnobotanical analysis of medicinal plants used for fever treatment in Yasothon Province, northeastern Thailand, and assesses informant agreement regarding their antipyretic use using the fidelity level (FL). Ethnomedicinal data were collected through semi-structured interviews, participant observation, and guided field walks with 108 informants from nine districts between April 2024 and February 2026, and records related to fever treatment were extracted for detailed analysis. Voucher specimens were collected and taxonomically verified. A total of 129 medicinal plant species belonging to 108 genera and 46 families were recorded. Fabaceae was the most represented family, while native species predominated (83.72%). Trees constituted the largest growth form (45.74%), and wild plants accounted for 62.02% of all recorded species. Roots were the most frequently used plant part (39.53%), and decoction was the principal preparation method (93.02%). Twenty-five species exhibited an FL value of 100%. These findings highlight the richness of traditional antipyretic knowledge in Yasothon Province and provide a useful baseline for the preservation of biocultural heritage and for future ethnopharmacological research on medicinal plants used in fever treatment.