Lactose intolerance and milk allergy: The difference

In short: Lactose intolerance is a digestive disorder due to a missing enzyme, milk allergy a defensive reaction to milk protein; both require different handling.

In more detail: Complaints after milk can have two very different causes. What matters is the right diagnosis by a doctor instead of treating yourself. This is general information and does not replace medical advice. With complaints, illnesses, pregnancy or medication, ask a doctor or pharmacist.

In Depth

Lactose intolerance

The body produces too little of the enzyme lactase, which splits milk sugar (lactose). Undigested lactose reaches the large intestine and is fermented by bacteria: bloating, stomach ache, diarrhoea, feeling of fullness, usually 30 minutes to 2 hours after consumption. It is not an allergy, not life-threatening, and many sufferers tolerate small amounts (for example a splash of milk in coffee). It is common worldwide and often increases in adulthood.

Milk allergy

The immune system reacts to milk protein (casein, whey proteins). Symptoms: skin rash, swelling, shortness of breath, vomiting, in the worst case anaphylaxis (life-threatening). It occurs mainly in infants and small children and often disappears later. Then all milk components must be strictly avoided, not just lactose; lactose-free milk does not help because it still contains the protein. Milk is one of the 14 main allergens highlighted on packaging.

Diagnosis

If suspected see a doctor: hydrogen breath test, diet and symptom diary, for allergy skin and blood tests, challenge under medical supervision. Coeliac disease, irritable bowel and other causes must be excluded. Your own elimination diets without consultation can cause nutrient gaps and complicate diagnosis.

Everyday life

With lactose intolerance: lactose-free products (with added lactase), hard cheese and yoghurt are often better tolerated, lactase tablets, plant drinks (oat, soy, almond) with calcium fortification. Watch ingredient lists: lactose is in bread, sausage, sauces and ready meals. With allergy: take notes such as “may contain traces of milk” seriously, emergency plan and possibly emergency kit. Make sure of enough calcium and vitamin D.

See also: The 14 main allergens, Fibre and protein, Reading the nutrition table, Labelling vegan and vegetarian