How do you know if you're intolerant to dairy?

Rose Constantine-Smith

You may get bloating, or stomach pains. Excessive burping or passing a lot of wind can occur. You may also get watery diarrhoea, and itching around your bottom (anus). These symptoms tend to develop from one to several hours after milk, dairy products or any food containing lactose.

https://patient.info/health/food-allergy-and-intolerance/lactose-intolerance#nav-3