Synopsis
Separate lactose malabsorption from clinical intolerance and milk allergy, recognise secondary mucosal disease, use breath testing or structured dietary challenge appropriately, and preserve calcium, vitamin D and dietary diversity.
- Lactase non-persistence causes reduced lactose absorption, but symptoms depend on dose, meal context, transit, colonic adaptation and visceral sensitivity; malabsorption is not identical to intolerance.
- Bloating, cramp, flatus and watery diarrhoea after lactose reflect osmotic retention and bacterial fermentation, not intestinal inflammation.
- Cow's-milk protein allergy is an immune reaction with a different history; urticaria, wheeze, angioedema or anaphylaxis needs urgent allergy assessment.
Key red flags
Rapid hives, swelling, wheeze, vomiting, hypotension or collapse after milk protein is an immune emergency, not lactose intolerance.
Investigation priorities
Change lactose exposure alone for a defined short period, record symptoms, then reintroduce a measured amount in a usual meal.
Management branches
Meal-linked symptoms occur without allergy or organic alarm features.
- Quantify lactose portions and associated foods, then reduce lactose alone for a short predefined interval while maintaining calcium-rich alternatives.
- Reintroduce a measured amount with food and record symptom threshold; use breath testing if the result remains unclear or major restriction is contemplated.
Key medicines
Lactase enzymeUse the product-specific oral dose with the first mouthful of a lactose-containing meal, adjusted to portion size and individual response.
Colecalciferol and calcium supplementationUse dietitian and BNF-guided supplementation only when dietary intake or measured vitamin D is inadequate, accounting for age, pregnancy, renal function and bone risk.