There are innumerable substances to which the immune system can become sensitive. There are the classic allergens, such as foods, environmental, and airborne allergens. But there are also a great many other things to which the body can react. In order to review the plethora of possible reactants, I have categorized them. The categories include infectants, also known as pathogens, ingestants, inhalants, environmental allergens, atmospheric conditions, and injectants. Of course, there are many more substances to which the body can become sensitive than have been described here. In fact, an individual can become sensitive to almost anything.
From my newest book, Clearing the Way to Health and Wellness.