Lactose Intolerance Signs in Toddlers


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Lactose intolerance in toddlers presents much the same as normal lactose intolerance. If the infant has inherited lactose intolerance, it will usually only develop after the age of 4 years. But there are many other reasons why lactose intolerance can develop.

Primary lactose intolerance

Normally, the amount of the enzyme lactase produced by the body reduces after the age of two and continues to decrease with age. So it is rare for an infant to have primary lactose intolerance from birth. Lactose intolerance usually fails to thrive, and suffer from dehydration and malnutrition. This is a medical emergency and they should be admitted to hospital for monitoring and put on a specialised diet immediately.

Secondary lactose intolerance

Secondary lactose intolerance, like in adults occurs when illness or injury damage the small intestine. Lactase is produced by in the lining of the small intestine, and so if damaged lactase levels can dramatically decrease. Reduced lactase activity can cause problems when digesting lactose. This is a big problem for infants, where there main source of nutrition is milk.

Examples of instances where the gut has been damaged in infants, causing secondary lactose intolerance are:

  • Coeliac disease
  • Gastroenteritis
  • Surgery to the gut
  • Medications
  • Another food intolerance or allergy e.g. milk protein

Secondary lactose intolerance is normally only temporary and is resolved if the underlying condition is treated. However, if the condition causing the lactose intolerance is chronic (long-term) then the lactose intolerance can remain for longer.

The infant may have food intolerance to a type of food the mother has eaten, as food the mother consumes passes to the infant via the breast milk. In this case, identifying the exact food intolerance can be extremely difficult. You would have to eliminate the suspected culprit food from the mother’s diet – you should consult a health professional before doing this.

The food intolerance causes upset to the infants’ digestive system, and inadvertently produces temporary lactose intolerance.

Gastroenteritis is the other main cause of secondary lactose intolerance in infants. The lactose intolerance can cause watery diarrhoea, which can leads to excessive dehydration. This is dangerous for infants and they should be admitted to hospital immediately. To combat the dehydration caused by the diarrhoea a rehydration solution is given. While lactose intolerance persists after gastroenteritis you should carefully monitor the infants nutritional status are malnutrition is a common side effect of lactose intolerance following gastroenteritis.

Gastroenteritis takes about a month to fully recover in its severest form, but for a young baby under 3 months this may stretch to 2 months. Older babies recover much more rapidly, sometimes within a single week.


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