Evidence check: IgE in the context of Müdigkeit

IgE (immunoglobulin E) is an antibody primarily involved in allergic reactions. Elevated IgE levels can indicate allergies (e.g., pollen, dust mites, foods) or parasitic infections. Fatigue is a highly nonspecific symptom. A direct causal link between IgE and fatigue is not strongly supported by evidence. However, allergies can indirectly cause fatigue through sleep disruption (e.g., allergic rhinitis) or chronic low-grade inflammation. The concept of 'allergic fatigue' exists clinically but lacks a clear biomarker definition. Importantly, a single IgE value without corresponding symptoms has limited diagnostic value. Consumer tests measuring IgE against many foods often yield false positives and are not recommended by medical guidelines. For unexplained fatigue, a comprehensive medical workup (e.g., CBC, thyroid, iron, sleep assessment) is essential. The evidence for IgE as a standalone fatigue marker is weak to moderate.