This is a tutorial for people searching for solutions for prolonged illnesses. It is also an introduction for scholars who are studying the limitations of the medical worldview. Food allergy, as a topic in medicine, has been actively suppressed for many years and is taught poorly or not at all in medical schools.

The first issue is the meaning and use of the term "allergy." There are different types of allergy. Hay fever is the most common expression of  allergy and is a prototype of immediate hypersensitivity, easily recognized because it involves quick and dramatic symptoms. This is referred to as immediate hypersensitivity.

Delayed patterns of allergy are not so obvious and generally go unrecognized. Allergy skin tests do not show this problem nor do blood antibody tests. The presence of  delayed patterns of food allergy is concealed in a variety of diagnoses such as migraine headaches, asthma, eczema, irritable bowel syndrome, depression, chronic fatigue, fibromyalgia, panic disorder, and arthritis. Patients with these problems tend to have two or more manifestations concurrently in a matrix of non-specific symptoms.

The difficulty in diagnosing food allergy and other food-related problems in medicine and disputes within the allergy community have left many patients suffering, frustrated and confused. At the same time as physicians default in the diagnosis and treatment of food-related illnesses, many non-medical practitioners have launched careers in the food and chemical "sensitivity" business, using diverse, sometimes curious and bizarre methods, dubious tests and questionable treatments.