6. Nausea
As already mentioned, some people have a more severe and immediate reaction to lactose. In these cases, it’s almost as if their body is trying to reject the lactose before even allowing it to enter the rest of the digestive system. Severe intolerance to lactose can trigger feelings of nausea and the urge to vomit, as the body reacts negatively to the ingestion of lactose-containing foods. If this is the case for you, your best bet probably is to listen to your body and throw it back up if you can.