9) Constipation
After the accelerated release of the first feces with remnants of milk sugar, the opposite of diarrhea can occur: constipation.
That is the presence of hard stool, along with a feeling of incomplete bowel movements, stomach upset, swelling, and excessive exertion. Constipation may be another indication of lactose intolerance, although it is a much uncommon symptom compared to diarrhea. It is mainly caused by an increase in methane production in the colon, and it is precisely the presence of that methane that slows the transit time in the intestine.
