Differentiating milk allergy (IgE and non-IgE mediated) from lactose intolerance: understanding the underlying mechanisms and presentations.

British Journal of General Practice, August 2016 e609 INTRODUCTION Children with food allergy and, in particular, infants with suspected adverse reactions to cow’s milk, commonly present to primary care. It is thought that 6–8% of children aged <3 years have a food allergy1 and up to 4.9% have a cow’s milk allergy.2 Inconsistencies in the management of food allergy prompted the commissioning of projects such as the National Institute for Health and Care Excellence (NICE) clinical guideline on the diagnosis and assessment of food allergy in the community1 and in 2014 the NICE Clinical Knowledge Summary looking specifically at the management of milk allergy.3 It has been shown that GPs’ knowledge of these guidelines is poor. Inconsistencies remain in the management of milk allergy, with a particularly lengthy time period and multiple consultations before diagnosis.4 There is anecdotal evidence of confusion between lactose intolerance and milk allergy among both patients and physicians, which could result in unnecessary dietary restriction or avoidable reactions. Terminology such as suspected ‘milk allergy’, ‘milk intolerance’, and also ‘lactose intolerance’ are often used without a clear sense of the different meanings, understanding of the different mechanisms that underlie them, or the dietary implications of the diagnosis. The management of these conditions is distinctly different, and inappropriate recognition or management may have significant implications for the patient. In the last 15 years, there have been many discussions on the nomenclature of reactions to foods, including milk. The currently accepted nomenclature is determined by the mechanism likely to be producing the symptoms, with cow’s milk allergy being immune mediated and lactose intolerance not immune mediated.1,2