Chronic diarrhea in a child means loose or watery stools that continue for 14 days or more. The definition is a duration threshold rather than a diagnosis. It marks the point where an acute illness has failed to resolve, and where the plausible causes are almost entirely different from those of acute gastroenteritis.
Three things sit behind that threshold. The first is a question of mechanism: the intestine is losing water or failing to absorb what passes through it, and the pattern of the stools narrows down which arm of that mechanism is at work. The second is celiac disease, a permanent immune-mediated intolerance of gluten that damages the mucosa, the lining of the small intestine. The third is inflammatory bowel disease (IBD) — Crohn’s disease, ulcerative colitis and an unclassified intermediate group — a chronic relapsing inflammation of the gastrointestinal tract.
Celiac disease and IBD are not forms of chronic diarrhea; both are diseases in their own right. They belong with it because prolonged loose stools are often what brings the child to medical attention in the first place. All three also share a red-flag set, and a single work-up logic runs through them: history and growth chart, then first-line non-invasive tests, then endoscopy only where it is pointed. What separates them is mechanism, definitive diagnosis and treatment, so the useful way to learn them is as a layered differential rather than as three unrelated topics.
Choose a route through this family
If the topic is new, begin with the two notes on mechanism and work-up. Together they establish the vocabulary of mechanism and the order of tests that the disease notes then assume. After them, celiac disease and IBD can be read in either order.
- Definitions and Mechanisms of Chronic Diarrhea in Children explains the duration thresholds, the four mechanisms that produce loose stools — osmotic, secretory, fat-malabsorptive and inflammatory — with the bedside and stool findings that tell them apart, and how the likely causes change with the age of the child.
- Clinical Approach and Work-up of Chronic Diarrhea in Children turns that vocabulary into a gated four-step work-up, sets out the red flags that override reassurance, and shows how a malabsorptive or an inflammatory pattern sends the child to a different endoscopy.
- Functional Diarrhea of Toddlerhood and Overflow Around Constipation describes the two non-organic patterns that dominate the differential in early childhood, one of which is a chronic diarrhea diagnosis and the other only mimics one.
Celiac disease runs from the disease itself, through its diagnosis, to its lifelong treatment.
- Celiac Disease in Children explains how common the disease is, the HLA genes that predispose to it and the mechanism behind it, the clinical forms including the ones without diarrhea, and how it differs from wheat allergy and non-celiac wheat sensitivity.
- Diagnosing Celiac Disease in Children follows the blood antibody tests, total IgA with anti-transglutaminase IgA, to the European pathway that diagnoses some children without a biopsy, and explains when biopsy and histology are still needed.
- Treating and Monitoring Celiac Disease covers the strict, lifelong gluten-free diet and the contamination that matters as much as the obvious sources, follow-up every 6 to 12 months, and the long-term risks that make the diet permanent.
IBD runs from recognition and diagnosis to treatment.
- Pediatric Inflammatory Bowel Disease explains how Crohn’s disease, ulcerative colitis and IBD-unclassified differ, when to suspect them in a child, how fecal calprotectin (a stool marker of intestinal inflammation) is read, how endoscopy and imaging make the diagnosis, and what predicts a more aggressive course.
- Treatment and Monitoring of Pediatric Inflammatory Bowel Disease covers inducing remission — nutritionally in Crohn’s disease, by severity-based drug treatment in ulcerative colitis — then maintenance with thiopurines and biologics, and the growth and surveillance questions that are specific to children.
How this connects to acute diarrhea
The acute diarrhea family already published on this site — Acute Diarrhea and Dehydration with its six companion notes — defines the opposite end of the time axis. Acute diarrhea lasts less than 7 days, is viral in most European children, and is managed by replacing fluid. This family begins where that reasoning stops. It reuses the same vocabulary of osmotic and secretory mechanisms, described for the acute setting in Pathophysiology of Acute Diarrhea and Dehydration, and then extends it into conditions that are defined by duration, and for which rehydration is not the answer.
Where this family stops
Several causes of prolonged loose stools appear here only as parts of the differential: cow’s milk protein allergy, cystic fibrosis, congenital enteropathies such as microvillus inclusion disease, parasitic infection and irritable bowel syndrome. Each has its own mechanisms and its own work-up, and none of them is covered in depth.
The same limit applies to deeper IBD treatment questions: which biologic to choose after failure of a first agent, how to switch, and the thresholds for therapeutic drug monitoring, the measurement of drug levels to guide dosing. These follow current guidance from ESPGHAN (the European Society for Paediatric Gastroenterology, Hepatology and Nutrition) and ECCO (the European Crohn’s and Colitis Organisation), and they are also outside this family. This family covers the childhood presentation, the diagnostic reasoning and the treatment framework; nothing here is intended as patient-specific advice.