[Extrinsic allergic alveolitis of drug origin]

Extrinsic allergic alveolitis of drug origin is now a better known branch of respiratory pathology. The symptoms and course of these cases resemble in many ways those of extrinsic allergic alveolitis in general with a few differences. The list of drugs responsible is longer every day, and it is important to be aware of it. The diagnosis of these diseases is not always easy, as there are certain similarities between them and other long diseases either iatrogenic or not, but not immuno-allergic. Our physiopathological knowledge is based on already known data concerning allergic alveolitis, but includes many theories which still have to be verified. It is important for the clinician to be aware of this new type of respiratory disease as the treatment includes withdrawal of the responsible drug as soon as possible, failing which irreversible pulmonary fibrosis develops.