Lactose intolerance is different from milk allergy. In milk allergy, the body is intolerant to milk proteins and not to milk sugar while the person who is lactose intolerant must avoid milk and different dairy products. A lactose intolerant person may show different symptoms like abdominal cramps, diarrhea and bloating.
People not having lactose intolerance do not make enzyme lactase needed to digest lactose into galactose and glucose. Without sufficient amount of lactase, the undigested lactose remains undigested and gets fermented by gut bacteria leading to bloating and digestive symptoms. Lactase production gets impaired with age. Thus, lactose intolerance is most commonly found in the older population.
The secondary symptoms of lactose intolerance include bloating, gas, abdominal cramps and gas. Few people experience an urgency to go to the toilet, nausea, constipation and pain in the belly. The symptoms range from a severe reaction to mild discomfort based on the amount of lactase deficiency is present. In severe cases, dehydration may occur.