Evidence check: Cortisol in the context of allergy

The provided context does not contain specific information on cortisol in relation to allergy. Generally, cortisol is a stress hormone with immunomodulatory effects; it can suppress inflammatory mediators and influence allergic responses. However, evidence for using cortisol measurements (e.g., saliva, hair) to guide allergy management is limited. Most studies show associations between chronic stress, elevated cortisol, and worsened allergy symptoms, but causality is not firmly established. Consumer tests marketing cortisol for allergy often rely on mechanistic reasoning rather than robust clinical validation. Without concurrent allergy markers (e.g., IgE, eosinophils) and medical interpretation, the clinical utility is low. Evidence is rated as mechanistic/unclear. Caution: cortisol levels fluctuate diurnally and are affected by many lifestyle factors; a single measurement is not diagnostic for allergy. No direct sources from the provided context.