wie lange vor allergietest keine antihistaminika — which blood markers matter?

This question addresses preparation for allergy testing. Antihistamines primarily affect skin tests (prick, intradermal) by blocking histamine release, potentially causing false negatives. Washout periods depend on the drug: short-acting (e.g., cetirizine, loratadine) should be stopped 3–7 days before testing; long-acting (e.g., desloratadine, fexofenadine) up to 10 days. For blood markers—specific IgE (sIgE), total IgE, eosinophils, tryptase—antihistamines do not directly alter antibody levels, so a washout is less critical. However, clinicians often recommend a pause to ensure consistent interpretation. Key blood markers for allergies include: sIgE to individual allergens, total IgE (elevated in atopy), eosinophil count, and tryptase for suspected anaphylaxis. Evidence for washout times is based on clinical practice guidelines, not high-quality trials. Caveat: Always consult your allergist; some patients require antihistamines for other conditions. Consumer IgG food intolerance tests lack validation and should not replace proper allergy diagnostics.