Food allergy can cause rapid, dramatic bloating by a mechanism that is not understood but probably involves increased blood flow through the small intestine with transfer to blood gases. Constipation consists often decreased frequency of bowel movement, often with harder stools that are difficult to pass. Skipping bowel movements for several days will usually result in abdominal bloating and tenderness. Constipation suggests a slowing of peristalsis, with accumulation of feces in the colon. Often the muscle of the colon will contract in a spastic manner blocking the passage of stool.
Many patients report alternating constipation and diarrhea.
They will describe days with no bowel movements followed by a burst of loose or watery stool often with crampy pain. Diarrhea is increased frequency of bowel movements with stools that are loose to watery. Some have defined diarrhea as more than 3 loose to watery stools per day. Often diarrhea contains increased mucous. The colon is somewhat like the nose in its tendency to secrete protective mucous with food allergy.