What does diarrhoea feel like with lactose intolerance?

Lactose is the natural sugar in milk. When the body does not digest it fully, it reaches the bowel where it can draw in water and be broken down by bacteria. This may produce loose or watery stools, rumbling, gas, and abdominal discomfort. Symptoms may begin after milk, ice cream, soft cheese, or other dairy foods, but the timing and severity differ between people. Similar symptoms can have other causes.

Record what you eat, how much dairy you have, when symptoms begin, and how long they last. Keep drinking fluids during loose stools. Do not remove all dairy for a long period without advice, because calcium and other nutrients still matter. A clinician or dietitian can discuss lactose-free choices, portions, and whether a supervised dietary trial or breath test is suitable. Check labels carefully if symptoms are frequent.

Seek medical advice if symptoms occur without dairy, continue despite avoiding lactose, or are accompanied by weight loss, persistent vomiting, fever, night-time diarrhoea, or poor growth in a child. Get urgent help for severe pain, fainting, dehydration, swelling of the lips or tongue, wheezing, or breathing difficulty, as these may signal a reaction other than lactose intolerance.

Ask whether your pattern suggests lactose intolerance, milk allergy, coeliac disease, or another bowel problem. Discuss a nutritionally balanced dairy reduction, suitable substitutes, and whether any medicines or supplements contain lactose. Mention rashes, swelling, breathing symptoms, or symptoms in other family members.