Tools for Practice

#321 “Not Milk?”: Avoiding lactose-containing products during acute pediatric diarrhea (Free)

Do lactose-containing formulas/diets worsen acute pediatric diarrhea?

Breastfed children should continue breastfeeding. In formula-fed children under two years, temporarily switching to lactose-free infant formula shortens diarrhea duration by ~18 hours and reduces treatment failure (9% versus ~17% control) at 24-72 hours. The effects of cow’s milk are investigated in only three small, older randomized controlled trials and results are likely unreliable.

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  • Results statistically different unless stated.
  • Four systematic reviews with 22-33 RCTs, 2215-2973 mostly hospitalized (clinically stable) formula-fed children with acute diarrhea receiving oral rehydration.1-4
    • Lactose-free versus lactose-containing products (infant formula/foods): Focusing on the largest systematic review (children’s ages 1-28 months),
      • Duration of diarrhea:1 Reduced by 18 hours with lactose-free formulas/foods.
        • Median diarrhea duration (calculation by PEER): ~2.75 versus ~3.5 days (lactose-containing).
      • Treatment failure (typically: Continued/worsening diarrhea or vomiting, need for rehydration, or weight loss).
        • 9% versus 17% (lactose-containing),1 number needed to treat (NNT)=14 over 24-72 hours.
        • Duration of hospitalization1 and weight:1,2,4 No difference.
      • Results of other systematic reviews similar.2-4
      • Diluted versus non-diluted lactose-containing formula.
    • Systematic review (9 RCTs, 687 children)1 found diluted (25-50%) lactose-containing formula reduced treatment failure: 11% versus 17%, NNT=17 over 24-72 hours.
      • Other found similar results.4
      • Diarrhea duration1,3,4 and weight:1,2 No difference.
    • RCTs in above systematic reviews comparing full-strength cow’s milk to:
      • Diet without milk: 2 RCTs5,6 (~70 children each, mean ages: 7-15 months)
        • Diarrhea duration: No difference.5,6
      • Diluting milk: 1 RCT7 (62 children, mean age: 22 months).
        • Treatment failure: No difference.
      • Limitations:
        • Many RCTs unblinded;1,5,6,7 baseline illness duration not reported;1-4 statistics difficult to clinically interpret.2,4
        • RCTs investigating the effects of cow’s milk are old5-7 (>30 years old) and not generalizable (gave cow’s milk to infants at 3-6 months).5
        • No RCTs in older children.
  • Acute diarrhea guidelines recommend:
    • Continued (or increased) breastfeeding, including during initial rehydration.8,9
    • Resumption of usual diet after rehydration.10,11
  • While guidelines suggest that changing/diluting formula may be unnecessary, recommendations were made prior to currently available systematic reviews.10,11

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  • Candra Cotton BSc Pharm
  • Jennifer Potter MD CCFP
  • Samantha Moe PharmD

1. MacGillivray S, Fahey T, McGuire W. Cochrane Database Syst Rev. 2013; 2013(10):CD005433.

2. Gaffey MF, Wazny K, Bassani DG, et al. BMC Public Health. 2013; 13 Suppl 3(Suppl 3): S17.

3. Florez ID, Veroniki A-A, Al Khalifah R, et al. PLoS ONE. 2018; 13(12): e0207701.

4. Brown KH, Peerson JM, Fontaine O. Pediatrics. 1994 Jan ;93(1):17-27.

5. Romer H, Guerra M, Pina JM, et al. J Pediatr Gastroenterol Nutr. 1991; 13:46-51.

6. Isolauri E, Vesikari T, Saha P, et al. J Pediatr Gastroenterol Nutr. 1986; 5:254-261.

7. Dugdale A, Lovell S, Gibbs V, et al. Arch Dis Child. 1982 ; 57(1) : 76-8.

8. World Health Organization. UNICEF: Clinical management of acute diarrhea WHO/Unicef joint statement. 2004. Available at : Accessed June 2, 2022.

9. A Leung, T Prince, Canadian Paediatric Society, Nutrition and Gastroenterology Committee. Paediatr Child Health. 2006; 11(8):527–531.

10. King CK, Glass R, Bresee JS, et al. MMWR Recomm Rep. 2003; 52(RR-16):1-16.

11. Farthing M, Salam M, Lindberg G, et al. World Gastroenterology Organisation Global Guidelines: Acute diarrhea in adults and children: a global perspective. 2012. Available at : Accessed June 2, 2022.

Authors do not have any conflicts of interest to declare.