Effect of H2 blockade in the challenged allergic nose

To examine whether H₂ blockade might prevent development of allergen-induced nasal congestion, we subjected 18 volunteers with allergic rhinitis to nasal allergen challenge after pretreatment with cimetidine or with placebo. Response after cimetidine was more severe than that which followed placebo. H₂ blockade has a subtle adverse effect on nasal allergic response.