What is secondary lactose intolerance?

Secondary lactose intolerance is a condition in which the body can't digest a sugar called lactose, which is found in dairy products. Usually, your body produces an enzyme called lactase that breaks down this sugar, but certain conditions like illness or injury cause the small intestine to produce less lactase. This means that the body can't digest the sugar as well. Secondary lactose intolerance usually causes digestive issues like diarrhea and stomach cramps after you eat or drink any dairy products.