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Back to Health Concerns

Diarrhea and Lactose

When diarrhea occurs, should we restrict milk products? In most cases, no. However, it is possible that certain individuals who are lactose intolerant may suffer from diarrhea after lactose ingestion.

As well, people using certain medications such as antibiotics could present with diarrhea which could lead to temporary lactose intolerance.

Milk is often thought to cause diarrhea, but a recent meta-analysis of 21 studies compared the effects of milk containing lactose with placebo in individuals with no gastro-intestinal problems to start with and concluded that lactose was not a major cause of gastrointestinal symptoms, including diarrhea.1

Diarrhea can be caused by many factors, including medications (particularly antibiotics), bacterial or viral infections, intestinal infections and functional bowel disorders, as well as by food intolerances.2,3 Many recent studies have demonstrated that fermented milk products - for example, yogurt that contains probiotics such as Lactobacillus acidophilus - may even be effective in treating antibiotic-associated diarrhea in adults.4-7


  1. Savaiano DA et al. Lactose intolerance symptoms assessed by meta-analysis: a grain of truth that leads to exaggeration. J Nutr, 2006. 136(4): p. 1107-13.
  2. Krause’s Food, Nutrition & Diet Therapy. 11th Edition, Saunders ed. 2004, Philadelphia: Elsevier (USA).
  3. NIH, Diarrhea. 2007, National Institute of Health. US Department of Health and Human Sciences.
  4. Salminen S. Functional dairy foods with Lactobacillus strain GG. Nutr Rev, 1996. 54(11 Pt 2): p. S99-101.
  5. Beausoleil M. et al. Effect of a fermented milk combining Lactobacillus acidophilus Cl1285 and Lactobacillus casei in the prevention of antibiotic-associated diarrhea: a randomized, double-blind, placebo-controlled trial. Can J Gastroenterol, 2007. 21(11): p. 732-6.
  6. Beniwal RS et al. A randomized trial of yogurt for prevention of antibiotic-associated diarrhea. Dig Dis Sci, 2003. 48(10): p. 2077-82.
  7. Pereg D et al. The effect of fermented yogurt on the prevention of diarrhea in a healthy adult population. Am J Infect Control, 2005. 33(2): p. 122-5.

Keywords: lactose intolerance

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