This site is intended for health professionals only

Symptom sorter – Diarrhoea in children

Diarrhoea in children

The final article in our series of abridged chapters from the recently updated Symptom Sorter, which gives a grassroots analysis of common presenting symptoms in primary care

The GP overview

This is a very common presentation and is usually caused by gastroenteritis or another acute infection. Less common is the subacute or prolonged case, where the differential is wider.

Differential diagnosis


• Gastroenteritis.

• Other systemic infection (such as UTI, otitis media, pneumonia).

• Toddler’s diarrhoea.

• Medication side-effects (usually antibiotics).

• Cows’ milk protein intolerance (CMPI).


• Lactose intolerance (typically following a bout of gastroenteritis in babies).

• Irritable bowel syndrome.

• Faecal impaction (causing overflow diarrhoea).

• Coeliac disease.

• Other infections such as giardia.


• Inflammatory bowel disease (IBD).

• Appendicitis (relatively common but in rare cases can present with diarrhoea).

• Intussusception.

• Cystic fibrosis.

Possible investigations




Stool culture if diarrhoea persists more than a week, is bloody or there is recent foreign travel, urinalysis, MSU, FBC, CRP, ESR, anti-endomysial and anti-gliadin antibodies, faecal calprotectin.

Small print

Hospital tests might be necessary for cystic fibrosis, IBD and to confirm coeliac disease.

Top tips

• It is not unusual for the diarrhoea in gastroenteritis to take a couple of weeks to settle. Consider a stool specimen if it is not starting to improve after a week.

• Don’t overlook faecal impaction as a cause of overflow diarrhoea. The clues are soiling and preceding constipation.

• Lactose intolerance tends to be confused with CMPI. The former is less common, typically follows gastroenteritis and is usually shortlived.

• Undigested food (‘peas and carrots syndrome’) in the persistent loose stool of an otherwise well and thriving child is usually harmless toddler’s diarrhoea.

Red flags

• In the acute case – particularly in younger children with severe diarrhoea and vomiting – assess for dehydration. If the child is significantly dehydrated, admission is needed regardless of cause.

• Bloody diarrhoea raises the stakes. In the acute situation, this could be a more severe gastroenteritis or, especially in those under 12 months, intussusception. Prolonged cases might be CMPI or IBD.

• Very minor, transient weight loss is common during a bout of gastroenteritis. More prolonged weight loss with persistent diarrhoea should, on the other hand, prompt urgent referral.

• Appendicitis can cause diarrhoea. In such cases, the abdominal pain is usually more marked and constant than in a typical gastroenteritis, where it is typically mild (and therefore not the presenting complaint) and intermittent.

Dr Keith Hopcroft is Pulse’s clinical adviser and a GP in Basildon, Essex


Visit Pulse Reference for details on 140 symptoms, including easily searchable symptoms and categories, offering you a free platform to check symptoms and receive potential diagnoses during consultations.