Lactose intolerance in adulthood: what to know

Lactase breaks lactose into smaller sugars that can be absorbed. When digestion is incomplete, bacteria in the colon ferment the lactose and draw in water. This can lead to abdominal pain, bloating, rumbling, gas or diarrhoea after milk or other dairy foods. The amount that causes symptoms varies; yoghurt and hard cheese may be easier to tolerate than a glass of milk. Similar symptoms can also come from another digestive condition, so a new or persistent pattern deserves assessment rather than self-diagnosis.

Keep a simple food-and-symptom diary, noting the food, portion and timing. A clinician may suggest a structured lactose reduction followed by a planned reintroduction, or discuss Food Intolerance Testing. Do not remove every dairy food without replacing its calcium, vitamin D and protein sources. Lactose-free milk, fortified alternatives and lactase products may help some adults; check labels and ask a pharmacist or clinician which option suits you. Nutrition Counselling can help build a balanced plan around foods you already enjoy.

Arrange an appointment if symptoms are persistent, worsening, occur without dairy, or are accompanied by weight loss, blood in stool, fever, repeated vomiting or symptoms that wake you. Seek urgent care for severe or rapidly worsening abdominal pain, faintness, marked dehydration or breathing difficulty. Those features need assessment because lactose intolerance itself does not explain every digestive or allergic reaction.

Ask whether your symptom timing fits lactose intolerance, whether another condition should be considered, and how to test tolerance safely. You can also ask how to meet calcium and vitamin D needs if you reduce dairy.