There is a growing body of evidence that altered reactivity of the tissues on reexposure to certain substances is the causative factor in the production of several diseases the causation of which has been obscure, such as periarteritis nodosa, dermatomyositis, acute glomerular nephritis and others. However, it is the allergic manifestations which appear on the covering and lining membranes of the body, that is, the skin and the mucous membranes of the respiratory and gastrointestinal tracts, which present the day by day problems in practice. These include the eczemas of the infantile, "atopic" and contact types; urticaria; coryzas of the seasonal and perennial varieties; asthma, and some disturbances of the gastrointestinal tract which are usually functional in nature and in which the tissue changes are generally reversible.
In uncomplicated cases, these allergic diseases seldom cause death, but their chronicity and the suffering and disability which they produce demand careful clinical
BULLEN SS. WHAT SHOULD THE GENERAL PRACTITIONER DO ABOUT ALLERGY?. JAMA. 1949;140(1):12-15. doi:10.1001/jama.1949.02900360014005