Lactose intolerance

• Limited capacity or inability to digest milk sugar (lactose).

• Often mistaken for or mixed with cows milk protein intolerance (which is an allergy to protein(s) in cows milk).

•  Is most commonly due to post-viral gastroenteritis lactase deficiency, e.g. rotavirus. Most cases are transient and short lasting (<4–6wks).

• In older healthy children and adults, lactase levels commonly decline with subsequent variable severity intolerance (especially in certain populations, e.g. South-east Asian and Afro-Caribbean).

• Rarely due to genetic congenital lactase deficiency (primary). Infants present with severe diarrhoea after lactose exposure.