Why do I get diarrhea when I catch a cold?

The reason for catching a cold and having diarrhea is that cold stimulation speeds up the peristalsis of the intestinal tract reactively, increasing the movement speed of food pellets. This causes a large amount of nutrients that cannot be absorbed by the intestinal tract to enter the rectum. These are rich in nutrients. Nutritious semi-food is quickly exploited by bacteria and releases a large amount of gas, which can also irritate the rectal wall and aggravate the feeling of defecation. Therefore, cold stimulation of the abdomen will cause diarrhea.