These are some of the possible causes of diarrhea in children:

Viral infections: “In younger kids, rotavirus is the most frequent cause of severe diarrhea and dehydration in the world,” says Dr. Neuspiel. These infections occur when children are together in large groups, such as daycares and schools. “Rotavirus is much more of a killer of younger kids in underdeveloped countries in Africa and elsewhere. It's very common in the US and fortunately doesn't cause many deaths but it does cause dehydration.” As children get older, other viral infections can also cause diarrhea.

Bacterial infections: At any age, bacteria, such as salmonella, shigella, campylobacter and E. coli can cause bloody diarrhea. “They're less frequently the cause of diarrhea in kids, but they can be more serious,” says Dr. Neuspiel. “Contaminated food and water in certain tropical countries could lead to some of these infections, but it's also not uncommon to pick them up in the US.”

Food intolerance: While infections are the most common cause of diarrhea, occasionally diarrhea is due to a food intolerance or allergy,” says Dr. Joseph Gigante. Chronic diarrhea may be related to lactose intolerance (an inability to digest lactose), which would typically start to show up in early childhood, according to Dr. Neuspiel. And cow milk protein allergy can also cause diarrhea.

Antibiotics: “Probably one of the most common side effects we see in children treated with antibiotics is the diarrhea that follows,” says Dr. Gigante. “Antibiotics not only treat whatever the child is infected with but will also sometimes kill some of the normal bacteria in the gut that help digest food, which leads to diarrhea.”