Allergy to drugs. Experience in 771 procedures

Drug hypersensitivity reactions (RHD) are those that present clinically as allergic. They can or cannot involve an immunologic mechanism of lesion. They are frequent and, occasionally, life threatening. Patients with RHD repeat the reaction when they are re-exposed to the drug, limiting the therapeutic options and exposing them to more expensive and toxic drugs. It is difficult to identify the responsible drug when the reaction was not recent or when it occurred in the context of therapy with multiple drugs or confusing concurrent diseases. The diagnosis should be based on clinical history, followed by drug skin tests and drug provocation tests. We describe our experience in 771 procedures, 331 cutaneous and 440 drug provocation tests, 11% of them were positive. Positive symptoms included generalized pruritus, rash, urticaria, angioedema, rhinitis, bronchospasm, nausea and anaphylaxis. All the patients with positive tests had a good response to treatment. It can therefore be concluded that drug tests undertaken on individuals with suspected drug allergy, performed by experienced personnel and in controlled settings, are useful and safe to confirm drug hypersensitivity.