Chronic Diarrhea in Teens: Causes, Risks & When to See a Doctor

Definition

Chronic diarrhea in adolescents is defined as loose or watery stools occurring ≥3 times daily for more than 4 weeks. At age 13, this warrants prompt medical evaluation.

Potential Complications

• Dehydration & electrolyte imbalance: Sodium, potassium, magnesium loss → fatigue, dizziness, arrhythmia risk.
• Malnutrition & growth failure: Reduced nutrient absorption → weight loss, stunted linear growth, vitamin/mineral deficiencies (iron, B12, D, zinc).
• Quality of life impact: School absenteeism, social anxiety, sleep disruption.

Common Causes in Adolescents

Category	Examples	Clues
Infections	Giardia, C. difficile, post-infectious IBS	Travel, antibiotics, outbreak exposure
Food-related	Lactose intolerance, fructose malabsorption, celiac disease	Bloating, post-prandial symptoms, family history
Inflammatory	Crohn’s disease, ulcerative colitis	Blood/mucus in stool, abdominal pain, weight loss, extraintestinal manifestations
Functional	Irritable bowel syndrome (IBS-D)	Pain relieved by defecation, change in frequency/form, no alarm features
Medication-induced	Antibiotics, metformin, laxative abuse	Temporal association
Malabsorption	Pancreatic insufficiency, SIBO, bile acid diarrhea	Steatorrhea (oily, foul-smelling stool)

Diagnostic Approach

• History: Onset, pattern, triggers, diet, medications, travel, family history, growth chart.
• Physical: Growth parameters, abdominal exam, perianal inspection.
• Initial labs: CBC, CMP, ESR/CRP, TSH, celiac serology (tTG-IgA + total IgA), stool studies (culture, ova/parasites, C. diff toxin, fecal calprotectin).
• Advanced: Breath tests (lactose, fructose, SIBO), endoscopy/colonoscopy with biopsy, imaging (MR enterography).

When to Seek Immediate Care

• Signs of severe dehydration (no urine >8 hrs, sunken eyes, altered mental status)
• Bloody diarrhea, high fever (>38.5°C / 101.3°F)
• Severe abdominal pain, distension
• Weight loss >5% body weight

Management Principles

• Treat underlying cause (e.g., gluten-free diet for celiac, biologics for IBD).
• Oral rehydration solution (ORS) for ongoing losses.
• Nutritional rehabilitation with dietitian guidance.
• Avoid empiric anti-diarrheals (loperamide) without diagnosis—can worsen invasive infections.