Lactose intolerance concerns digestion of milk sugar; milk allergy is a reaction to milk protein. The difference affects food choices and investigation. Lactose-free cow’s milk still contains milk protein.
Several problems can follow a meal
Lactose intolerance commonly causes gas, bloating, cramps and diarrhoea. The amount of lactose that causes symptoms varies. Milk allergy can produce other reactions and needs its own assessment. Timing after a meal alone does not establish either diagnosis.
Symptoms after milk can have other explanations too. Avoid removing several major food groups indefinitely without a plan. It becomes difficult to identify what helped and to make sure nutritional needs are met.
Two different clinical questions
| Question | Lactose intolerance | Milk allergy |
|---|---|---|
| What is involved? | Milk sugar is not digested adequately. | Milk protein triggers an allergic reaction. |
| Does lactose-free milk help? | May be an option according to tolerance. | Still contains milk protein; it is not a milk-free substitute. |
| How is assessment chosen? | From symptoms and a planned dietary assessment. | From the reaction pattern and allergy assessment. |
Keep a useful food and symptom diary
- What did you eat or drink and approximately how much?
- When did symptoms begin and how long did they last?
- Were symptoms confined to the gut or did skin and breathing change too?
- Did the same thing happen on another occasion?
Bring the diary to your vårdcentral, a primary care centre. Ask whether a time-limited dietary change is appropriate and how it will be evaluated. Do not deliberately reproduce a reaction at home after breathing problems or another severe reaction.
Does a genetic test provide the whole answer?
No. It can identify a genetic tendency towards lower lactase production, but does not establish that lactose causes your current symptoms. Ask what a proposed test would change.
When to get help in Sweden
Call 112 for a severe allergic reaction with breathing difficulty or feeling faint. Contact primary care for recurring bowel symptoms, blood in stool or weight loss. Children need age-appropriate assessment and dietary advice; prolonged exclusion diets should not be started without guidance. Call 1177 if you are unsure about urgency.
Sources and further reading
- 1177: Laktosintolerans (in Swedish)
- 1177: Komjölksallergi (in Swedish)
- Region Skåne: IBS, irritabel tarm (in Swedish)
Sources and links checked on 22 October 2026. Editorial team: Hagakliniken. General information; individual assessment may differ.