Why you suddenly have problems with milk

Sometimes, lactose intolerance develops when the small intestine’s production of lactase decreases after an illness. Photo: TNS

What would cause someone to become lactose-intolerant later in life?

Lactose intolerance isn’t a true allergy, and it can develop at any age. In some people, lactose intolerance may be triggered by another medical condition, such as Crohn’s disease. In others, it develops without a specific underlying cause.