Dairy intolerance, also known as lactose intolerance or dairy sensitivity, occurs when the body has difficulty digesting lactose—the natural sugar found in milk and dairy products. This happens due to a deficiency of lactase, the enzyme responsible for breaking down lactose in the small intestine.

Without enough lactase, undigested lactose ferments in the gut, leading to uncomfortable symptoms such as bloating, gas, diarrhea, and stomach cramps. Unlike a dairy allergy, which triggers an immune response, dairy intolerance primarily affects digestion and varies in severity from person to person. Many people with dairy intolerance find relief by avoiding milk-based products or opting for lactose-free and dairy-free alternatives.