What is primary lactose intolerance?

Primary 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 as people get older, their bodies produce less lactase and can't digest the sugar as well. Primary lactose intolerance usually causes digestive issues like diarrhea and stomach cramps after you eat or drink any dairy products.