Evidence check: IgG Unverträglichkeitstest in the context of fatigue

The IgG food intolerance test is often marketed to identify triggers for vague symptoms like fatigue. However, current evidence does not support its use: IgG antibodies reflect immune exposure, not intolerance or allergy. Major allergy and immunology societies (e.g., EAACI, AAAAI) advise against IgG testing for diagnosis. Fatigue has numerous potential causes – sleep disorders, nutritional deficiencies, chronic infections, or stress. Relying on an IgG test may lead to unnecessary dietary restrictions or false reassurance, delaying proper medical evaluation. A thorough clinical workup, including validated allergy tests (IgE) and symptom diaries, is more appropriate. The evidence for IgG testing in fatigue is best described as 'marketing' – it lacks robust clinical validation.