What should you know about lactose intolerance?

Lactose is the natural sugar in milk and many dairy foods. When it is not broken down well, it reaches the colon, where bacteria ferment it and draw in fluid. This can lead to bloating, cramps or abdominal pain, rumbling, gas, and diarrhoea after dairy. The timing and intensity vary with the amount consumed and the person's tolerance.

Lactose intolerance is different from a milk allergy. An allergy involves the immune system and may cause hives, swelling, wheezing, or vomiting. New intolerance can sometimes follow an intestinal illness or another condition affecting the gut, so a sudden change is worth discussing.

Keep a food and symptom diary rather than removing every dairy food without a plan. Some people tolerate small portions, yoghurt, or hard cheese better than milk. Lactose-free products or lactase products may help, but check labels and follow professional advice.

If you reduce dairy, replace its nutrients with suitable alternatives. Nutrition counselling can help you choose calcium- and protein-containing foods, particularly for children, pregnancy, or restricted diets. A clinician may recommend food intolerance testing or another assessment when the pattern is unclear.

Seek urgent help for breathing difficulty, facial or throat swelling, collapse, or widespread hives after milk, as these suggest allergy rather than intolerance. Arrange a review for blood in stool, persistent vomiting, fever, dehydration, unexplained weight loss, symptoms that wake you, or ongoing diarrhoea.

Ask whether your symptoms fit lactose intolerance, whether another bowel condition should be considered, how to test your tolerance safely, and how to maintain calcium and vitamin intake if dairy is limited.