Is IgE Allergietest useful for fatigue?

An IgE allergy test (measuring specific IgE antibodies to foods or inhalants) is generally not useful for isolated fatigue without accompanying allergic symptoms (e.g., urticaria, dyspnea, eczema). Fatigue is a highly nonspecific symptom with many potential causes: sleep deprivation, iron deficiency, thyroid dysfunction, depression, chronic infections, or lifestyle factors. Allergies can contribute to fatigue (e.g., in seasonal rhinitis or untreated food allergy), but a positive IgE result alone does not prove a causal link. Moreover, many positive IgE findings are clinically irrelevant (sensitization without disease). Guidelines recommend IgE testing only when allergy is suspected based on symptoms and history. Screening for allergies in fatigue is not evidence-based and may lead to misinterpretation, unnecessary dietary restrictions, and costs. A structured medical workup is recommended instead.