1. Diarrhea
One of the most common symptoms of lactose intolerance, diarrhea can occur when undigested lactose acidifies the colon, leading to an increase in osmotic load that results in watery stools. This doesn’t have to be major, long-lasting diarrhea. It could be that just the first one or two time you use the washroom your stools are looser, or maybe you find yourself heading to the bathroom more urgently than usual after consuming.