wie lange vor allergietest kein cetirizin — which blood markers matter?

The question addresses two aspects: how long to stop cetirizine before an allergy test and which blood markers are relevant. For skin prick tests, antihistamines like cetirizine should generally be discontinued 3–7 days beforehand because they suppress the histamine response and can cause false-negative results. The exact duration depends on the specific drug and individual half-life; cetirizine has a half-life of about 8–10 hours, but its effect on the skin may persist longer. For blood tests (specific IgE), discontinuation is not necessary because antibodies are measured and are not affected by antihistamines. The key blood markers for allergy testing are specific immunoglobulin E (sIgE) to individual allergens and total IgE as a supportive value. Eosinophil counts and tryptase can provide additional clues for allergic or mast cell-mediated reactions. The evidence is based on clinical practice and guidelines (e.g., EAACI), not on the provided context. Note: When in doubt, consult a physician, as individual factors (e.g., renal function) may influence the washout period.