4. Nausea
As you might expect, all of these unpleasant symptoms can also add up to cause nausea. This is a result of the body trying to reject the unwanted substance. Nausea the vast majority of the time is the result of the body thinking that something is wrong and therefore trying to purge itself.
When you have all the symptoms described above such as nausea, bloating, diarrhea, and stomach pain, this of course rather suggests to the body that something is wrong. The result is that you can begin to bring up the contents of your stomach. This may remove some of the lactose before it makes it as far as the bowels but it certainly isn’t a pleasant experience at the time.