wie lange vor allergietest kein cetirizin — what are common causes?

Cetirizine (a second-generation antihistamine) should generally be discontinued 3–7 days before an allergy skin prick test, as it suppresses the histamine-induced wheal response and can cause false-negative results. The exact duration depends on the specific drug and individual half-life; for cetirizine, 3–5 days is common, but up to 7 days may be needed after long-term use or higher doses. Common reasons for this washout include: blockade of H1 receptors preventing wheal formation, and slower drug elimination in patients with renal impairment. Other antihistamines (e.g., loratadine, desloratadine) have similar required intervals. Important: Always consult your doctor before stopping any medication, especially if allergy symptoms are severe. The evidence is based on clinical practice guidelines and expert consensus, not large randomized trials. Caveat: No washout is needed for oral food challenges or specific IgE blood tests.