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What's causing my infant's diarrhea?

Medically reviewed by Last updated on Apr 8, 2021.

Although frequent diarrhea is common among children, it can be difficult to determine exactly what's causing it.

Chronic diarrhea can have many causes, including:

  • Bacterial or parasitic infection, which is a rare cause in developed countries
  • Celiac disease — an immune reaction to eating gluten, a protein found in wheat, barley and rye
  • Chronic inflammation of the digestive tract (inflammatory bowel disease), such as ulcerative colitis or Crohn's disease
  • Chronic, nonspecific diarrhea of childhood — a condition that typically occurs in children ages 1 to 3 for which no cause can be found and which usually resolves on its own without causing weight loss or poor growth
  • Dietary protein or sugar intolerance
  • Irritable bowel syndrome

Rare causes of chronic diarrhea also include:

  • Neuroendocrine tumors — tumors that typically start in the digestive tract
  • Hirschsprung's disease — a condition present when a baby is born (congenital) that results from missing nerve cells in the muscles of part or all of the baby's colon
  • Cystic fibrosis — an inherited disease that can lead to a buildup of thick mucus that prevents the body from absorbing nutrients from food
  • Eosinophilic gastrointestinal disorders — a group of complex diseases characterized by higher than normal amounts of white blood cells, called eosinophils, in organs in the digestive system
  • Zinc deficiency

In children, slower than normal growth or weight loss accompanying diarrhea may indicate that the stomach and intestine are having difficulty absorbing nutrients — common in cases of celiac disease or cystic fibrosis — while other problems may be more difficult to diagnose.

When to see a doctor

In children, particularly young children, diarrhea can sometimes lead to dehydration. This is especially true if the diarrhea is combined with a fever or vomiting or both. Call your doctor if your child's diarrhea doesn't improve after 24 hours or if your baby:

  • Hasn't had a wet diaper in three or more hours
  • Has a fever of more than 102 F (39 C)
  • Has bloody or black stools
  • Has a dry mouth or cries without tears
  • Is unusually sleepy, drowsy, unresponsive or irritable
  • Has a sunken appearance to the abdomen, eyes or cheeks
  • Has skin that doesn't flatten if pinched and released

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