• Lactose Intolerance


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


    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.

    Risk Factors

    Factors that may increase your chances of lactose intolerance:


    Symptoms of lactose intolerance generally begin within 2 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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    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.


    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 calcium and other food elements that are hard to replace. If complete elimination is chosen, then careful replacement of calcium is needed for good health.
    Treatments include:

    Dietary Changes

    Keep a food diary of what you eat and what the reaction is. Discuss the findings with your doctor or a dietitian.
    Dietary changes may include:
      Eat smaller amounts of milk or milk products with a meal. It may reduce symptoms. Many people can tolerate 4-8 ounces of milk. You may have better tolerance for some of the following dairy products made from milk:
      • Hard cheeses, such as cheddar and Swiss
      • Yogurt
    • Try lactose-free milk and lactose-reduced milk and milk products.
    • Ask a dietitian for help choosing substitutes for dairy products or recommending supplements to ensure that you eat enough calcium.
    • Nondairy foods rich in calcium include:
      • Salmon
      • Sardines
      • Cooked spinach
      • Oranges
      • Broccoli
      Read product labels because other foods can contain lactose including:
      • Breads
      • Baked goods
      • Processed cereals
      • Instant potatoes, soups, and breakfast drinks
      • Margarine
      • Processed meats
      • Liquid and powder milk-based meal replacements
      • Protein powders and bars
      • Salad dressings
      • Candies
      • Pancake mixes
      • Non-dairy coffee creamers and whipped toppings
      Other words that indicate lactose are:
      • Whey
      • Curds
      • Dry milk solids
      • Nonfat dry milk
      • Milk by-products
    • Be aware that some medications may contain small amounts of lactose.


    Your doctor may recommend lactase enzymes if you can tolerate only small quantities of lactose. The enzyme supplements come in liquid and chewable form. A few drops of the liquid added to milk, which is allowed to sit overnight, can decrease the amount of lactose in the milk. Tablets are chewed or swallowed before eating foods that contain lactose.


    There are no current guidelines to prevent lactose intolerance.


    American College of Gastroenterology http://patients.gi.org

    American Gastroenterological Association http://www.gastro.org


    Canadian Association of Gastroenterology https://www.cag-acg.org

    Dietitians of Canada http://www.dietitians.ca


    Heyman MB. Lactose intolerance in infants, children, and adolescents. Pediatrics. 2006;118(3):1279-1286.

    Lactose intolerance. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: https://www.niddk.nih.gov/health-information/digestive-diseases/lactose-intolerance. Updated June 2014. Accessed October 3, 2017.

    Lactose intolerance in adults. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T115565/Lactose-intolerance-in-adults. Updated November 17, 2016. Accessed October 3, 2017.

    Lactose intolerance in children. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T306336/Lactose-intolerance-in-children. Updated June 22, 2016. Accessed October 3, 2017.

    Montalta M, Curigliano V, Santoro L, et al. Management and treatment of lactose malabsorption. World J Gastroenterol. 2006;12(2):187-191.

    National Institutes of Health. National Institutes of Health (NIH) 2010 consensus development conference statement on lactose intolerance and health. 2010;22-24;27(2).

    Understanding food allergies and intolerances. American Gastroenterological Association website. Available at: http://www.gastro.org/info%5Ffor%5Fpatients/2013/06/06/understanding-food-allergies-and-intolerances. Updated September 2017. Accessed October 3, 2017.

    Revision Information

    • Reviewer: EBSCO Medical Review Board Daus Mahnke, MD
    • Update Date: 12/31/2013
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