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Definition  

Lactose intolerance is gastrointestinal upset due to the inability to digest significant quantities of lactose. Lactose is a sugar found in milk and other dairy products.

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Causes  

Lactose intolerance is caused by a reduction in the digestive enzyme lactase. Lactase breaks down the sugar lactose into sugars that can be more easily absorbed. When not fully broken down, lactose ferments in the colon and causes symptoms.

Some people are born unable to make lactase. Others develop the intolerance over time.

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Risk Factors  

Factors that increase your risk of lactose intolerance include:

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Symptoms  

Symptoms of lactose intolerance generally begin within two hours of consuming milk or other dairy products. The severity of symptoms depends on how much lactase your body produces and how much lactose you eat.

Lactose intolerance may cause:

  • Cramping
  • Bloating
  • Abdominal rumbling sounds
  • Gas
  • Diarrhea
  • Loose stools
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Diagnosis  

The doctor will ask about your symptoms and medical history. A physical exam will be done. Your doctor may recommend a trial period of eating no milk or milk products to see if symptoms resolve.

Your doctor may want to perform tests to help make the diagnosis. These may include:

  • Hydrogen breath test
  • Stool acidity test

Your doctor may recommend a biopsy to examine intestinal tissue.

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Treatment  

Temporary lactose intolerance following an infection usually goes away after the intestine heals.

Treatment for chronic lactose intolerance focuses on managing symptoms. For most people, removing dietary lactose, especially in children and adolescents, would not be recommended. Milk and milk products provide sources of