The successful treatment of hay fever, asthma and eczema, like the successful treatment of other diseases, depends on a complete understanding of the patient and his particular problem. In the allergic diseases this is especially true because, as Pirquet1 has described, the symptoms depend on the peculiar capacity of the individual to react toward certain foreign substances. Not only must the physician understand the physiologic changes in the body of his patient, but particularly in the cases of hay fever, asthma, eczema and the other manifestations of allergy he must understand the patient's environment, his contacts with the various foreign substances that it may contain, and his reaction to these contacts. Recent clinical experience has led to the use of certain "tricks" in history taking in allergic diseases which are of such practical importance that their recognition constitutes a virtual advance in diagnosis and treatment.
First of all, the