Mohamed et al identified predictors for true penicillin allergy in a patient who gives a history of penicillin allergy. The authors are from Heart of England NHS Foundation Trust Birmingham.

Patient selection: history of penicillin allergy


Predictors of true allergy:

(1) history of anaphylaxis (OR 30.6)

(2) hospitalization for the reaction (OR 7.0)

(3) less than 5 years since the index reaction (OR 3.0)



Other serious systemic reactions such as Stevens-Johnson Syndrome could be used in addition to anaphylaxis.


The risk increases with the number of predictors present.


The absence of predictors does not exclude penicillin allergy but can identify a patient at low risk.

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