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Lactose Intolerance

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Signs and Symptoms

Signs and symptoms associated with lactose intolerance are due primarily to undigested lactose reaching the large intestine. Extra fluids are drawn into the large intestine, where bacteria break down the lactose, producing hydrogen gas and lactic acid. This can cause:

  • Abdominal pain and cramps
  • Abdominal bloating
  • Excessive gas, flatulence
  • Nausea
  • Diarrhea

The type and severity of symptoms vary by individual and by the amount and kind of dairy products consumed. Many people with lactose intolerance can consume small amounts of dairy products with few to no symptoms.

Lactose intolerance should not be confused with an allergy to cow's milk. A milk allergy involves a reaction by the immune system and is directed against a protein in the milk, not a sugar. Although some of the symptoms may be similar, a person with a milk allergy can have a mild to severe or even life-threatening reaction within minutes to hours after drinking milk. In addition to digestive symptoms, those with a milk allergy may experience hives and wheezing. Lactose intolerance is more common in adults than in children. Milk allergies are common in young children but are also frequently outgrown.

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