Lactose intolerance is a clinical condition characterized by the inadequate hydrolysis of lactose due to a deficiency in the lactase enzyme, which is essential for its digestion in the small intestine. This enzymatic insufficiency impairs the breakdown of lactose into glucose and galactose, resulting in gastrointestinal symptoms such as abdominal pain, bloating, and diarrhea following the ingestion of lactose-containing foods. The condition can arise from primary genetic factors or secondary causes and exhibits variability in symptom severity among individuals. Lactose intolerance is also known as lactose malabsorption.