Does taking zyrtec or Claritin (loratadine) before a methacholine challenge affect the results?

Mrthacholine test. Methacholine challenge test for asthma is not affected by zyrtec, claritin, allegra, Benadryl (diphenhydramine) or any other antihistamines. The test can be blocked or affected by bronchodilators like albuterol, xopinex, adrenaline etc.