The first version of this work was originally the thesis that Dr Michel Pradal submitted for his Doctorate of Medicine in 1987. Thanks to Pharmacia & Upjohn Diagnostics Division, this first version was published in French in 1990, and received positive reviews among the French allergist community. Two years later, in 1992, we published a second edition, this time in English, in the hope that this work might be a practical help to allergists facing difficulties in making etiologic diagnoses of drug allergies. These difficulties reside in the fact that where drug allergy is concerned, there is but one general rule: "there are no general rules". Each drug has its own metabolites and mechanisms, and the diagnostic tools must be adapted to the type of reaction caused by the drug in question and to the mechanisms involved.
Seven years after this second edition, we thought it would be useful to publish an updated version enriched with up-to-date knowledge and recent references. To achieve this, I asked dermatologist and allergist Doctor Michel Castelain to join Doctor Pradal and myself and enrich this work particularly in regard to delayed allergic reactions which often show skin reactions.
I hope that all the information found here will be useful in the day-to-day practice of allergology, and I thank Pharmacia & Upjohn for its material support.
Daniel Vervloet

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.