This stretching causes pain, usually what we call a cramp or gripe. Nausea may also develop. In addition, the small bowel temporarily stops contracting, resulting in a loss of bowel tone. This first leads to a sensation of bloating and eventually may produce abdominal swelling. When these abnormal contractions eventually relax, the high pressure between them is released.
Urgent stools tend to develop after heavy meals.
In some people, the enzyme needed to absorb milk sugar is absent so ingestion of raw milk products leads to diarrhea. Finally, despite all of the above, IBS patients rarely have symptoms at night once they have gone to sleep. Some patients have one or the other, but many will alternate between the two. Neither x-rays nor blood test measure intestinal contractions. X-rays look at the permanent anatomy of the bowel.