What should you know about severe lactose intolerance?

Lactose is the natural sugar in milk. When the small intestine does not make enough lactase, lactose reaches the colon undigested, where bacteria break it down and produce gas and fluid. This can lead to abdominal pain, bloating, rumbling and diarrhoea after dairy. Symptoms may depend on the food, portion and your individual tolerance. Lactose intolerance is different from a milk allergy, which can involve hives, swelling, wheezing or other allergic reactions.

Keep a food-and-symptom record and look for patterns rather than removing every food at once. Many people can use lactose-free milk or smaller portions, and some tolerate yoghurt or hard cheese better than milk. Avoiding dairy completely without guidance can make it harder to meet calcium and vitamin needs. A clinician may discuss food intolerance testing and a nutrition counsellor can help build a balanced plan. Check packaged foods for milk ingredients and ask about lactase products before relying on them.

Arrange medical advice if symptoms are persistent, severe, cause weight loss, wake you at night or lead to dehydration. Seek urgent help for fainting, severe or worsening abdominal pain, blood in stool, repeated vomiting, facial swelling or breathing difficulty. These features can point to another digestive problem or an allergic reaction rather than lactose intolerance alone.

Ask whether your symptoms fit lactose intolerance, whether another condition should be checked, and how to trial lactose reduction safely. Discuss which dairy alternatives provide calcium and vitamin D, whether testing is useful, and when to review the plan if symptoms continue.