Frequent loose bowel movements. Diarrhea is acute when it starts suddenly and clears up within a few days. Most people have diarrhea once in a while, usually after eating or drinking contaminated food or liquid or when they have stomach flu.
Diarrhea that doesn't go away after a few days or keeps coming back is called chronic. It may be a sign of other medical problems.
Diarrhea can be serious in very young children and older adults because it can cause dehydration (a loss of too much fluid from the body).