What should you know about low lactose intolerance?

Low lactose intolerance usually refers to difficulty digesting lactose, the natural sugar in milk, rather than a separate medical condition. When the small intestine makes too little lactase, lactose can pass into the colon without being fully broken down. Bacteria there ferment it, which may lead to bloating, abdominal pain, rumbling, gas, or diarrhoea after milk or dairy foods. The amount that causes symptoms varies from person to person.

Lactose intolerance is different from a milk allergy. Intolerance mainly affects digestion, while an allergy involves an immune reaction and can cause symptoms such as hives, swelling, wheezing, or vomiting. Some people tolerate small portions, yoghurt, or hard cheese more easily than a glass of milk. Lactose-free milk contains the same key nutrients as ordinary milk but has lactose already split into simpler sugars. Symptoms after dairy can also have other causes, so a pattern alone cannot confirm lactose intolerance.

A clinician may assess your symptoms, diet, and medical history. They may suggest a planned reduction followed by careful reintroduction, or arrange food intolerance testing when another explanation needs consideration. Do not remove all dairy for a long period without planning replacement sources of calcium, vitamin D, protein, and other nutrients.

Keep a brief food-and-symptom record. Note the dairy food, approximate portion, timing, and symptoms that follow. This can show whether the problem is linked to lactose and whether portion size matters. Try lower-lactose choices, lactose-free alternatives, or smaller portions with meals rather than making a broad, permanent restriction on your own. Check labels because lactose may be present in milk powder, cream, sauces, desserts, and some processed foods.

If symptoms continue, arrange an appointment with a general practitioner or dietitian. Nutrition counselling can help you preserve a balanced diet while testing which foods you tolerate. Seek advice before changing an infant’s or child’s milk intake, because growth and nutrition need special consideration.

Arrange medical review if digestive symptoms are persistent, severe, worsening, or interfering with eating, sleep, work, or school. Contact a clinician promptly for unexplained weight loss, blood in the stool, black stools, repeated vomiting, fever, dehydration, or diarrhoea that does not settle. Sudden swelling of the lips or throat, breathing difficulty, faintness, or widespread hives after dairy may indicate a serious allergic reaction; seek emergency help immediately.

You could ask: Could another digestive condition explain these symptoms? Should I try a structured lactose reduction and reintroduction? How can I meet my calcium and vitamin D needs if I reduce dairy? Would food intolerance testing be useful in my situation?