What role does IgG play in Allergie?

IgG antibodies play a complex but secondary role in allergies. While IgE mediates classic immediate-type hypersensitivity, IgG – especially the IgG4 subclass – is associated with tolerance induction and long-term effects of allergen immunotherapy. Elevated IgG levels to foods are often marketed as 'food intolerance' tests, but clinical evidence is weak. IgG-based food allergy tests are not recommended by professional societies because they merely reflect exposure, not allergy. In venom or drug allergies, IgG4 can serve as a biomarker for successful desensitization. Evidence is human-strong for IgG4 in immunotherapy, but human-weak for IgG food tests. Consumers should be aware that IgG tests do not diagnose allergies and often lead to unnecessary dietary restrictions. For suspected allergy, IgE testing and clinical history remain the gold standard.