Background: The term "intolerance" is not mentioned in the World Allergy Organization (WAO) document on allergy nomenclature. "Intolerance" has been used to describe some non-immunological diseases. However, pediatric gastroenterologists mix allergy and intolerance, e.g. by using the term "cow's milk protein allergy/intolerance (CMPA/I)", lumping together all types of mechanisms for not tolerating cow's milk. The basis for this mix is the fact that double-blind oral food challenges are time-consuming and expensive. Therefore, cow's milk exclusion and reintroduction is proposed to be used in primary care for the diagnosis of CMPA in children with common gastrointestinal (GI) problems such as colic and constipation. This may lead to a widespread use of hypoallergenic formulas in children without proven CMPA. In lay language, intolerance describes "not tolerating".
Objective: To discuss the reasons why the term "intolerance" should not be used in the area of allergy.
Results: Presently, intolerance is not part of the allergy nomenclature. It is used by lay persons to describe "not tolerating". Pediatricians use intolerance to describe non-immunological hypersensitivity such as lactose intolerance which is acceptable. However, using the mixed term CMPA/I describing a variety of gastrointestinal symptoms in children, should be avoided. The WAO Nomenclature does not clearly distinguish between non-IgE-mediated allergy and non-allergic hypersensitivity.
Conclusion: The term "intolerance" should not be used within the area of allergy. Intolerance should be better defined and the term restricted to some non-immunological/non-allergic diseases and not mixed with allergy, e.g. by using the term CMPA/I. A revision of the WAO nomenclature is proposed.
Keywords: Allergy; Cell mediated allergy; IgE sensitization; IgE-mediated allergy; Immunologically mediated hypersensitivity; Intolerance; Nomenclature; Non-IgE-mediated allergy; Non-allergic hypersensitivity; Non-immunologic hypersensitivity.