Toddler Diarrhoea

Toddler diarrhoea, also called functional diarrhoea of childhood or chronic non-specific diarrhoea, is the daily painless recurrent passage of three or more large unformed stools, symptoms lasting 4 weeks or more, onset between 6 and 60 months, passage of stool during waking hours, no failure to thrive when caloric intake is adequate.

• The commonest cause of chronic diarrhoea in children aged 1 to 5 years; prevalence about 1.5 to 7 percent of toddlers; resolves spontaneously by 4 to 5 years (often by school age).
• Mechanism: accelerated intestinal transit, with contributions from dietary factors: excess fruit juice and sweetened drinks (sorbitol, fructose malabsorption), low dietary fat and fibre, high fluid intake, carbohydrate malabsorption, and rapid gastrocolic reflex. Stools often contain undigested vegetable matter ("peas and carrots").
• Growth and development are normal. It does not cause nutritional deficiency in children with an adequate diet; dietary restriction (low fat, excessive elimination) can induce poor growth and should be avoided.

• Three to six or more loose or watery stools daily, foul smelling, containing undigested food, with mucus but no blood, occurring when awake (rarely nocturnal), with the first stool of the day often formed and later stools looser.
• Child is thriving, active, with good appetite, normal weight and height, no pain, no vomiting, no fever.
• Dietary history: fruit juice (apple, pear), sugar free sweets, squash, milk volume, fat and fibre intake, fluids over 1 to 1.5 litres.
• Examination: normal growth on centile charts, no pallor, no abdominal distension, no clubbing, no perianal soreness except mild.
• Red flags: failure to thrive or weight loss, onset before 6 months, nocturnal diarrhoea, blood in stool, fever, vomiting, abdominal pain or distension, steatorrhoea, recurrent chest infections (cystic fibrosis), oral ulcers, rash, clubbing, family history of coeliac disease or inflammatory bowel disease, travel history or contacts, immunodeficiency, diarrhoea starting after antibiotics.

• Clinical diagnosis from history, growth chart review, and 3 day food and stool diary.
• If red flags or doubt: stool culture, ova, cysts and parasites, Giardia antigen, Clostridioides difficile toxin when appropriate, faecal calprotectin, faecal elastase, reducing substances and pH, coeliac serology (tissue transglutaminase IgA with total IgA), full blood count, CRP, electrolytes, albumin, thyroid function, sweat chloride test, HIV test if indicated, cow's milk protein allergy assessment.
• Differentials: post-infectious diarrhoea, cow's milk protein allergy, lactose intolerance, coeliac disease, giardiasis, cystic fibrosis, inflammatory bowel disease, pancreatic insufficiency, constipation with overflow, antibiotic effects, laxative misuse.

• Reassurance and explanation: harmless, self-limiting, and not caused by infection or allergy.
• Normalise the diet (the mainstay):
  • Limit fruit juice to no more than 120 mL daily (ideally diluted or none), and avoid sugar free and sorbitol containing products.
  • Give adequate fat (about 35 to 40 percent of energy in toddlers; do not use low fat milk before age 2) and appropriate fibre from fruits, vegetables and whole grains.
  • Offer regular meals and snacks, normal amounts of fluids (water and milk; about 1 to 1.2 litres daily), avoid grazing and excessive milk.
  • Avoid restricted or exclusion diets without a diagnosis.
• Do not use antidiarrhoeal drugs (loperamide is contraindicated in young children because of risk of ileus and respiratory depression) or antibiotics.
• Oral rehydration solution only if dehydration occurs with intercurrent gastroenteritis.
• Nappy rash: barrier cream.
• Follow up in 4 to 6 weeks with a growth check; refer if poor growth, red flags or no improvement after dietary changes.