Or any antihistamine, really. Researchers at the University of Zurich have found that mice who are given antihistamines after an initial exposure to bee venom react more violently to subsequent exposures than mice who are not given antihistamines
They believe this is because the mice aren't able to build up tolerance to a given level of allergen. The researchers also found that exposure to antihistamines lowered the effectiveness of future immunotherapy, contrary to popular reports.
The study can be read in full in the most recent issue of "Clinical and Experimental Allergy"