Hypersensitivity to Pyrazolone Drugs

There is a group of patients who are hypersensitive to pyrazolone analgesics, but not to the aspirin-like drugs (Szczeklik et al. 1977 a). These patients, more often 

Mean age (years) Males/females Family history of atopy Positive skin tests with common aeroallergens Serum IgE Administration of noramidopyrine 

Often elevated Leads to anaphylactic shock or urticaria and/or angioedema 

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