It is quite normal to see some variation in the consistency of a baby’s stools, but if there is a sudden change in consistency to loose or watery stools, it is classed as diarrhoea


As well as loose, watery stools, associated symptoms may include:

  • Stomach cramps
  • Nausea and vomiting
  • Headache
  • Loss of appetite
  • Dehydration.

If diarrhoea lasts longer than 48 hours in babies aged between three months and one year, or if a baby passes six or more diarrhoeal stools in 24 hours, refer parents to a GP.

Babies are at high risk of dehydration, so parents should monitor them closely if they have diarrhoea or sickness


A common cause of diarrhoea is a viral or bacterial infection – in other words, a ‘tummy bug’. This is normally self-limiting and will clear up on its own within a couple of days. It may also be a sign that the baby is having difficulty digesting lactose or has an allergy to cows’ milk protein.


Parents should continue to offer the same feeds as usual. Older babies should be offered frequent sips of water. If babies don’t want to eat, drinks should still be offered regularly to prevent dehydration. An over-the-counter oral rehydration solution may also be suitable.

Babies are at high risk of dehydration, so parents should monitor them closely if they have diarrhoea or sickness. Signs of dehydration include drowsiness, passing little urine, glazed eyes, and a dry mouth or tongue. If babies show any of these signs, they should see a doctor immediately.

If a baby has diarrhoea, it is important that everyone in the family washes their hands regularly with soap and warm water to avoid spreading the infection.

Clinical summary:

The most common cause of diarrhoea in infants is gastroenteritis – mostly viral in origin, but sometimes caused by a bacterial or protozoal infection – and is usually self-limiting.

According to NICE, red flag symptoms, i.e. those that indicate a diagnosis other than gastroenteritis, include:

  • Fever (38ºC or higher in babies under three months of age, or 39ºC in infants older than this)
  • Shortness of breath
  • Altered consciousness
  • Neck stiffness
  • Bulging fontanelle
  • Non-blanching rash
  • Blood or mucus in stools
  • Bilious vomit
  • Severe or localised abdominal pain and abdominal distension or rebound tenderness.

During assessment, healthcare professionals should be alert to the signs of dehydration – altered responsiveness, decreased urine output, sunken eyes, tachycardia, tachypnoea, reduced skin turgor and general malaise – and clinical shock, which may manifest as decreased level of consciousness, pale or mottled skin, cold extremities and weak peripheral pulses. These are more common in infants aged under one year (and particularly those younger than six months), babies who were of low birthweight, and individuals who have had more than five diarrhoeal stools or two bouts of vomiting in the previous 24 hours or who cannot tolerate fluids (including breast milk).

In most cases, the main aim of treatment is to prevent dehydration by continuing breastfeeding and other milk feeds, encouraging fluid intake (though not fruit juice or carbonated drinks) and offering oral rehydration therapy (ORT). The latter should be used in all individuals who show signs of dehydration, ideally frequently and in small amounts.

Intravenous fluids may be indicated if clinical shock is suspected, and for children who cannot tolerate ORT or who continue to deteriorate despite taking it. If the child is on solid foods, these should be stopped while ORT is being given, but reintroduced immediately once the child has become rehydrated. Antidarrhoeal medicines, such as loperamide are not recommended, and antibiotics should not be given routinely.

Most children who have gastroenteritis can be safely managed at home, with advice and support from a healthcare professional on the need for scrupulous handwashing and other hygiene practices, awareness of the signs of dehydration and when to seek medical help.


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