Eosinophil peroxidase (EPX) is a marker of eosinophilic inflammation in allergic diseases. Currently, measuring EPX in nasal swabs as a surrogate for airway eosinophil levels is completed using a gold standard enzyme-linked immunosorbent assay (ELISA) lab test. The purpose of this project was to develop and validate a novel lateral flow assay (LFA) that measures EPX with the same sensitivity and range of detection as the gold standard EPX ELISA, but that can be efficiently used in clinical settings. The results of this project show that the EPX LFA is a promising method for measuring EPX in nasal swab samples. While future studies are needed for further validation, the EPX LFA could provide rapid point-of-care EPX measurements for clinicians and patients suffering with eosinophil-associated diseases.