Lactose Intolerance and Gastroenteritis

Gastroenteritis is usually caused by a viral infection. It occurs in all ages, particularly children under 5 years old. It occurs when you come into contact with contaminated food and/or drink.


Symptoms include:

  • Diarrhoea
  • Vomiting
  • Fever
  • Refusal to eat
  • Stomach cramps

Why does Gastroenteritis cause temporary lactose intolerance?

Gastroenteritis is the most common cause of secondary lactose intolerance; the occurrence of lactose intolerance due to injury or illness to the stomach lining. Gastroenteritis causes damage to the intestinal wall, disrupting normal digestion. The damaged walls of the intestine and stomach cause a decrease in the enzyme lactase – this means lactose will accumulate in the gut without sufficient lactase to digest it. This causes temporary lactose intolerance until the digestive system has had time to repair itself.

Gastroenteritis in adults

Gastroenteritis is an infection of the gut caused by a virus. In adults it is commonly caused by the noravirus and food poisoning. The common symptoms of gastroenteritis are watery diarrhoea which leads to dehydration. This happens because the infection causes your body to absorb more water from the intestines. Gastroenteritis usually resolves within a few days. If you it does not you should consult your doctor, they may give you a rehydration solution to help relieve the symptoms. The elderly and infants are the most at risk of excessive dehydration.

Gastroenteritis in infants

Gastroenteritis is an inflammation of the gut lining, causes by an infection. The infection is usually viral. The most common viral cause in children under 2 is the rotavirus. Symptoms include:

  • Pain
  • Drowsiness
  • Fever

Gastroenteritis is the one of the main causes 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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