What should you know about lactose intolerance symptoms?

Lactose is the natural sugar in milk. When the enzyme lactase is limited, undigested lactose reaches the colon, where it is broken down by bacteria. This can lead to bloating, cramping, excess gas, rumbling and loose stools. Abdominal pain is a common presentation of lactose intolerance, and diarrhoea may follow dairy intake. Symptoms often depend on the amount eaten and may start after a delay, so keeping a food and symptom diary can reveal a pattern. Lactose intolerance is different from a milk allergy, which can involve skin, breathing or swelling symptoms.

Write down the dairy food, portion, timing and symptoms rather than removing many foods without guidance. Some people tolerate small amounts, yoghurt or hard cheese better than a large glass of milk; lactose-free alternatives may also help. Read labels for milk, whey and other dairy ingredients, and keep calcium-containing foods in your routine. A clinician can discuss a structured reduction and reintroduction plan. If the pattern is unclear, [Food Intolerance Testing](/treatments/diagnostics-and-screening/food-intolerance-testing/) or [Nutrition Counselling](/treatments/lifestyle-and-wellness/nutrition-counselling/) may help identify a safe approach.

Arrange medical advice if symptoms persist, disturb sleep, cause weight loss, or continue despite avoiding lactose. Seek urgent help for severe or worsening abdominal pain, repeated vomiting, blood in stool, fainting, breathing difficulty, or swelling of the lips or tongue. A new persistent change in bowel habit should be assessed rather than attributed to lactose intolerance alone.

Could another digestive condition explain this pattern? Should I try a supervised lactose reduction? How can I maintain calcium and vitamin intake? Would testing be useful before I change my diet?