Diarrhoea is defined as the passage of three or more loose or liquid stools per day, lasting up to 14 days.1 A change to loose or liquid stool consistency rather than stool number is more indicative of diarrhoea in infants.1 Diarrhoea is generally obvious to identify, however, the following cases indicate a healthy infant and should not be confused with diarrhoea:1,2

  • Healthy newborn stools are soft and loose
  • Newborn babies pass stools frequently, sometimes after every feeding
  • Breastfed infants often have pasty stools

What causes diarrhoea in infants?
In infants worldwide, diarrhoea is usually caused by an infection from a virus, e.g. Rotavirus and Norovirus, or bacteria, e.g. Campylobacter or Salmonella.3 Other causes of infant diarrhoea include parasites, a reaction to a medicine, or a rare disease, such as cystic fibrosis2. In either case, diarrhoea may also be accompanied by vomiting,1 which may increase the risk of dehydration.1 Dehydration is the main risk associated with diarrhoea, therefore it is important to ensure that infants remain hydrated.

Diarrhoea as a symptom of Cows' Milk Allergy
Diarrhoea is the most common gastrointestinal symptom related to Cows' Milk Allergy (CMA) and affects more than half of all children with CMA.4-6

The majority of infants affected with CMA have at least two symptoms affecting at least two different organ systems.7,8 If you suspect non-IgE mediated CMA, you can use the CoMiSS® tool11 to score the combination of their symptoms and assess the likelihood of CMA.

Other signs and symptoms related to CMA4-6

  • Gastrointestinal/Digestive: Vomiting, reflux, regurgitation, anorexia, diarrhoea, constipation, abdominal pain, blood in stools
  • Respiratory: Chronic cough, sneezing, wheezing, shortness of breath, runny nose
  • Skin: Rash, atopic dermatitis, urticaria, angioedema
  • General: Failure to thrive, anaphylaxis, insomnia, inconsolable crying, pallor and tiredness
Changing baby’s diaper

How to score this symptom with the CoMiSSTM tool
  • The CoMiSS® tool uses the well-established Bristol stool scale12 to evaluate stool consistency
  • Diarrhoea should only be scored if it lasts for at least one week
  • In addition to the stool score, if any of the following signs or symptoms related to CMPA are also present, they should also be given a score using the CoMiSSTM tool. These include crying, regurgitation, skin (atopic dermatitis and urticaria) and respiratory symptoms


The Cows' Milk-related Symptom Score (CoMiSSTM) is a simple, fast and easy-to-use awareness tool designed to help you more easily recognise the signs and symptoms that can be cows' milk-related in infants and young children.


If you suspect your patient is suffering from symptoms that may be suggestive of CMA, use the CoMiSSTM tool to score and assess the likelihood of CMA.

Other Symptoms of Cows' Milk Allergy


  1. WHO. 2013. Diarrhoeal disease factsheet No.330. http://www.who.int/mediacentre/factsheets/fs330/en/ (Accessed April 2016)
  2. MedlinePlus. Diarrhoea in Infants https://medlineplus.gov/ency/patientinstructions/000691.htm(Accessed April 2016)
  3. Guarino A., et al. JPGN 2014;59:132–152
  4. Koletzko S., et al. J Pediatr Gastroenterol Nutr. 2012;55(2):221–9
  5. Luyt D., et al Clin Exp Allergy, 2014;44:642–672
  6. National Institute of Health Care and Excellence Clinical Knowledge Summarises. Cows’ milk protein allergy in children, 2015 http://cks.nice.org.uk/cows-milk-protein-allergy-in-children#!diagnosissub/-617759 (Accessed October 2016)
  7. Hill D., et al. J Pediatr. 1986;109:270–6
  8. Iacono G., et al. N Engl J Med. 1989;339:1100–4
  9. Lifschitz C. and Szajewska H. Eur J Pediatr. 2015;174:141–50
  10. Høst A and Halken S. Endocr Metab Immune Disord Drug Targets, 2014, 14, 2-8.
  11. Vandenplas Y., et al. Acta Paed. 2015;104:334–9
  12. Lewis S. and Heaton K. Scand J Gastroenterol. 1997;32(9):920–4

IMPORTANT NOTICE: Mothers should be encouraged to continue breastfeeding even when their babies have cows' milk protein allergy. This usually requires qualified dietary counselling to completely exclude all sources of cows' milk protein from the mothers’ diet. If a decision to use a special formula intended for infants is taken, it is important to follow the instructions on the label. Unboiled water, unboiled bottles or incorrect dilution can make babies ill. Incorrect storage, handling, preparation and feeding can eventually lead to adverse effects on the health of babies. Formula for special medical purposes intended for infants must be used under medical supervision.