J Invest Allerg Clin
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J Invest Allerg Clin · May 1996
Positive allergological tests may turn negative with no further exposure to the specific allergen: a long-term, prospective, follow-up study in patients allergic to penicillin.
Preliminary literature reports suggest the possibility that, in an allergic patient, a previously positive allergological test may turn negative after a long period of time with no further exposure to the specific allergen. The aim of this study was to evaluate the rate by which a previously positive skin test or RAST may turn negative in a group of patients allergic to penicillin if no further exposure to the specific allergen occurs. Sixty-three patients allergic to penicillin (48 with type I allergy and 15 with type IV allergy) were enrolled in a long-term, prospective, follow-up study, undergoing a successive complete allergological testing within 6 years of the first positive examination. ⋯ Our results provide strong evidence that a positive allergological test performed in a drug-allergic patient may become negative with time, in the absence of further exposure to the specific antigen. A negative allergological test cannot, therefore, rule out the immunological basis of a drug sensitivity. This is why we always suggest advising patients with a personal history of drug hypersensitivity against any further administration of the responsible drug, even in the presence of a completely negative allergological examination.