Diarrhoea management: to go lactose-free or not?

This article presents an overview of the current evidence for managing childhood diarrhoea and the importance of early refeeding.

Young children with acute diarrhoea, typically due to infectious gastroenteritis, may temporarily stop producing the intestinal enzyme lactase (Figure 1). This is commonly referred to as secondary lactase deficiency. If young children are unable to digest and absorb lactose because of lactase deficiency then, continuing to ingest lactose-containing milk or milk products may worsen acute diarrhoea due to the osmotic effects of undigested lactose in the colon.1,2 This may exacerbate dehydration, malabsorption, malnutrition, and growth failure.1

To feed or not to feed

Early refeeding reduces illness duration and improves nutritional outcomes.3 Not feeding until the diarrhoea has resolved (gut rest) is unnecessary, since some absorptive and digestive ability is retained.4 Mothers who breastfeed should continue their normal feeding practice once their child is rehydrated. Likewise, for formula-fed children, full strength milk formula should be provided after rehydration therapy.5 Dilution of milk formula is not recommended as this may prolong symptoms and delay nutrition recovery.3 Fruit juices or carbonated drinks should not be provided during diarrhoea.5

Milk matters

Lactose is the most abundant sugar in mammalian milk and in most cow milk-based formulas. Many consensus guidelines recommend the continued use of lactose containing milk feeds during acute diarrhoea once infant is rehydrated.5,7,9 However, a recent Cochrane review in young children with acute diarrhoea who were not predominantly breastfed, found that a change to a lactose-free diet may result in earlier resolution of acute diarrhoea and reduce treatment failure.1 Soy based formulas are naturally lactose-free, and may be recommended for the management of acute diarrhoea during secondary lactase deficiency.8 In a study of children with acute gastroenteritis and mild to moderate dehydration due to intolerance to cow’s milk, the use of soy formula was shown to significantly reduce the duration of diarrhoea and hospital stay.9

A little known fact is that lactose malabsorption in children may persist after the diarrhoea episode. Davidson et al estimated that it could take between 2 to 8 weeks for the secondary lactose intolerance to resolve, with younger children recovering more slowly than older ones.10

Clinical Pearls
  • Rehydrate
    It is important to rehydrate quickly to replace fluid and electrolyte losses.
  • Refeed
    Soy formulas and lactose-free cow milk formulas are widely available and may be recommended for the management of acute diarrhoea resulting in secondary lactase deficiency.
    Duration of use of lactose free formulas can range up to 2 to 8 weeks depending on the severity of the symptoms and the age of the child.


1. Macgilivray S et al. Cochrane Database Syst Rev 2013:10.
2. Lasekan JB, et al. Clin Pediatr (Phila) 2011;50:330-7.
3. Centers for Disease Control and Prevention. MMWR Recomm Rep. 2003;52:1–16.
4. Thapar N, Sanderson IR. Lancet 2004;363:641-653.
5. National Institute for Health and Clinical Excellence (NICE). CG84 Diarrhoea and vomiting in children under 5: quick reference guide. March 2010.
6. Guarino A, Albano F et al. JPGN 2008;46:S81-S122.
7. Heyman MB. Pediatrics 2006;118:1279.
8. Bhatia J, Greer F, AAP. Pediatrics 2008;121:1062-1068.
9. Santosham M, et al. Pediatrics. 1985;76:292-8.
10. Davidson GP, et al. J Pediatr 1984;105:587-590.


Last updated on 26 Feb 2015

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