Lactose intolerance is a physiological response to poorly digested and/or absorbed lactose in the gut due to lactase deficiency or inactivity and does not involve the immune system.⁶ Cows’ milk protein allergy is an adverse immune system reaction to cows’ milk protein that can be either immunoglobulin E (IgE) or non-IgE mediated.⁶

Lactose intolerance and cows’ milk protein allergy are often incorrectly used interchangeably due to similarities in the gastrointestinal clinical symptoms.³ Misdiagnosis or delayed diagnosis may result in inappropriate treatment options and/or unnecessary dietary restriction.³