Lactose intolerance

Lactose intolerance means that you have trouble digesting foods with lactose in them. Lactose is the natural sugar found in milk and foods made with milk. Between 30 million and 50 million Americans are lactose-intolerant.1 Lactose intolerance is common, but it may be especially harmful for women, as it may raise a woman’s risk for health problems such as osteoporosis.

What is lactose intolerance?

If you have lactose intolerance, your body cannot digest lactose, the sugar found naturally in milk and milk products. Most people are born with the ability to digest lactose, but up to 75% of people lose the ability as they grow older.3

Lactose intolerance causes symptoms such as stomach cramps and diarrhea after you eat foods with lactose. Although it is uncomfortable, the condition is not medically serious.

What is the difference between lactose intolerance and a milk allergy?

Lactose intolerance is not the same as a milk allergy.

  • Lactose intolerance is a problem with the digestive system. It causes uncomfortable symptoms but is not life-threatening.
  • A milk allergy is caused by a problem with your body’s immune system. Milk allergies are more common in children younger than 3. Symptoms can range from mild (rashes or itching) to severe (trouble breathing or wheezing). A life-threatening reaction caused by an allergy is called anaphylaxis. Anaphylaxis is a medical emergency. Call 911 right away if your child has any symptoms after drinking milk or eating foods with milk. Most children eventually outgrow milk allergies.

What foods have lactose?

Lactose is found in milk and all milk products, such as yogurt, cheese, and ice cream. It is also added to many prepared foods, such as:

  • Breads and other baked goods
  • Cereals
  • Frozen dinners
  • Instant potatoes, soups, and breakfast drinks
  • Lunch meats
  • Margarines
  • Mixes for cakes, cookies, pancakes, and biscuits
  • Nondairy liquid and powdered coffee creamers
  • Salad dressings

Check the Nutrition Facts label for products with lactose, milk, or milk byproducts. These may also be listed as whey, curds, or nonfat dry milk powder.

What are the symptoms of lactose intolerance?

Symptoms of lactose intolerance include:

  • Diarrhea
  • Nausea
  • Stomach cramps
  • Bloating
  • Gas

Symptoms usually begin within 30 minutes to two hours after you eat or drink foods with lactose.

How is lactose intolerance diagnosed?

Talk to your doctor or nurse if you have symptoms of lactose intolerance. Your doctor or nurse may ask you to stop eating foods with lactose for a few weeks to see whether your symptoms stop.

Your doctor may give you a test to see whether you have lactose intolerance. Common tests include:

  • Breath tests. Your doctor measures the hydrogen level in your breath. High levels mean you likely have lactose intolerance.
  • Blood tests. Your doctor will ask you to drink milk or a lactose solution. A blood test will then show whether your lactose or glucose levels rise.

How is lactose intolerance treated?

For most people, lactose intolerance does not require treatment. Instead, your doctor or nurse will talk to you about how to prevent the symptoms of lactose intolerance. This includes limiting or avoiding foods that have lactose, such as milk and foods made with milk.

How can I prevent the symptoms of lactose intolerance?

Some ways to help prevent symptoms include the following:

  • Limit the amount of foods with lactose that you eat.
  • Take a lactase tablet just before eating foods with lactose. The tablet gives your body the lactase it is missing.
  • Choose lactose-reduced or lactose-free dairy products. These products have the same nutrients as milk, including calcium and vitamin D.

Can I eat some dairy products if I am lactose intolerant?

Maybe. Some people with lactose intolerance can eat a small amount of certain foods with lactose. For instance, you may be able to eat yogurt or aged cheeses, like cheddar or Swiss. Or you may find that you can tolerate milk if you drink it in small amounts or only at meals. Regularly having some dairy products may help keep lactose intolerance from getting worse.4

If you cannot tolerate any amount of milk or milk products, you should find other ways to get enough calcium and vitamin D. Calcium and vitamin D are needed for healthy bones and teeth and essential functions of the body like a steady heartbeat. Ask your doctor or nurse whether you should take a calcium or vitamin D supplement every day. Or you can try lactose-free dairy products.

How does lactose intolerance affect women’s health?

Lactose intolerance may prevent you from getting enough calcium and vitamin D, which are important for bone health. Calcium and vitamin D are found in many foods with lactose, including milk and milk products.

Women especially need to get enough calcium and vitamin D throughout life to help build and maintain bone density and reduce the risk of osteoporosis  later in life. Osteoporosis is a condition that causes bones to weaken and break easily. More women than men are at risk for osteoporosis.

If you are lactose-intolerant, your doctor or nurse will likely talk to you about how to get more calcium and vitamin D each day. A dietary supplement may give you the amount you need to help prevent osteoporosis, or you can try lactose-free dairy products.


  1. Food and Drug Administration. (2017). Problems Digesting Dairy Products?
  2. Misselwitz, B., Pohl, D., Fruhauf, H., Fried, M., Vavricka, S.R, Fox, M. (2013). Lactose malabsorption and intolerance: pathogenesis, diagnosis and treatment. United European Gastroenterol J; 1(3): 151-159.
  3. Mattar, R., de Campos Mazo, D.F., Carrilho, F.J. (2012). Lactose intolerance: diagnosis, genetic, and clinical factors. Clinical and Experimental Gastroenterology; 5: 113-121.
  4. Szilagyi, A. (2015). Adaptation to Lactose in Lactase Non Persistent People: Effects on Intolerance and the Relationship between Dairy Food Consumption and Evaluation of Diseases. Nutrients; 7(8): 6751-6779

Source: Page last updated: March 02, 2018.

April 5, 2019
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