Lactose Intolerance


What is lactose intolerance?

Lactose intolerance is the inability to digest lactose, the sugar primarily found in milk and dairy products. It is caused by a shortage of lactase in the body, an enzyme produced by the small intestine that is needed to digest lactose. While lactose intolerance is not dangerous, its symptoms can be distressing.

Who is affected by lactose intolerance?

For most people, lactose intolerance develops over time as the body produces less lactase.

It is estimated that 36% of Americans and 68% of the world population have some degree of lactose intolerance. Lactose intolerance affects people from certain ethnic populations and races—such as Latin Americans, African-Americans, Native Americans, Asians, East Europeans and Middle Easterners—more than others.

How do I know if processed foods contain lactose?

When buying food, read the ingredients on food labels carefully. Ingredients derived from milk that contain lactose include:

  • Whey.
  • Cheese.
  • Milk by-products.
  • Dry milk solids.
  • Lactose.
  • Butter.
  • Curds.
  • Nonfat dry milk.
  • Dry milk powder.

Also avoid items that state "may contain milk" on the food label. Depending on the severity of your symptoms, you may need to avoid or limit foods containing these ingredients.

The following ingredients come from milk and do not contain lactose:

  • Casein
  • Lactalbumin
  • Lactate
  • Lactic acid

Lactose is also present in about 20% of prescription medications, such as birth control pills (oral contraceptives), and about 6% of over-the-counter (OTC) medications, such as some tablets for stomach acid and gas. Viactiv® calcium chews contain lactose and should be avoided while following a lactose-free diet.

These medications usually affect only people with severe lactose intolerance. Ask your healthcare provider which medications contain lactose, and read the labels on over-the-counter medications to check their lactose content.

Foods that contain lactose in small quantities include:

  • Bread and baked goods.
  • Milk chocolate and some candies.
  • Salad dressings and sauces.
  • Breakfast cereals and cereal bars.
  • Instant potatoes, soups, rice and noodle mixes.
  • Lunch meats (other than kosher).
  • Cheese flavored crackers and other snacks.
  • Mixes for pancakes, biscuits, and cookies.
  • Margarine and butter.
  • Organ meats (such as liver).
  • Sugar beets, peas, lima beans.
  • Certain coffee creamers.

Symptoms and Causes

What causes lactose intolerance?

Lactose intolerance is caused by a shortage of lactase in the body, an enzyme produced by the small intestine that is needed to digest lactose. Certain digestive diseases (such as Crohn’s disease, ulcerative colitis, and celiac disease), stomach or intestinal infections, and injuries to the small intestine (such as surgery, trauma, chemotherapy, or radiation therapy) may reduce the amount of lactase available to process lactose properly. If the small intestine is injured, lactose intolerance may be temporary, with symptoms improving after the intestine has healed.

What are the symptoms of lactose intolerance?

Symptoms of lactose intolerance include nausea, cramps, gas, bloating, or diarrhea within 30 minutes to 2 hours after consuming milk or dairy products. Symptoms occur because there is not enough lactase being produced by the body to digest the lactose consumed. The severity of symptoms varies, depending on the amount of lactose an individual person can tolerate. Some people may be sensitive to extremely small amounts of lactose-containing foods while others can eat larger amounts before they notice symptoms.

Diagnosis and Tests

How is lactose intolerance diagnosed?

The most common test for the diagnosis of lactase deficiency is the hydrogen breath test. This test is done at an outpatient clinic or doctor's office. In practice, many doctors will ask patients who suspect they have lactose intolerance to avoid milk and dairy products for 1 or 2 weeks to see if their symptoms subside, and will then confirm the diagnosis with the hydrogen breath test. The hydrogen breath test measures the amount of hydrogen in the breath after drinking a lactose-loaded beverage.

Management and Treatment

How is lactose intolerance treated?

Lactose intolerance is easily treated. The goal of treatment is to manage symptoms through dietary changes.

People with lactose intolerance can usually find a level of lactose-containing foods that will not produce symptoms. You can learn through trial and error what amount and type of lactose-containing products you can tolerate or you can temporarily eliminate all lactose-containing foods from your usual diet using a Lactose-Free Diet, then gradually add them back to find your level of tolerance and comfort.

For trial and error, try having smaller portions of your usual dairy foods, substituting them with lactose-free dairy products, or consuming milk and dairy products with meals because lactose may be better tolerated when eaten with other foods. Further, you may be may notice better tolerance of certain dairy foods that contain lower amounts of lactose, such as cheese, yogurt and cottage cheese.

Living With

Lactose-free diet

If desired, a lactose-free diet should be followed for two weeks. If symptoms have subsided after the 2-week strict diet, gradually add foods with lactose back into the diet slowly and monitor tolerance. You may be able to tolerate up to 12 grams of lactose at one time.

Lactose content of milk and milk products

High-lactose foods

The following foods contain approximately 5-8 grams of lactose:

Milk (whole, reduced fat, fat-free, buttermilk, goat's milk)1/2 cup
Evaporated milk1/4 cup
Cheese spread and soft cheeses2 oz.
Cottage cheese3/4 cup
Ricotta cheese3/4 cup
Yogurt, plain1/2 cup
Ice cream3/4 cup
Heavy cream1/2 cup
Non-fat dry milk powder2 Tbsp

Low-lactose foods

The following foods contain approximately 0-2 grams of lactose:

Condensed milk1/2 cup
Half and half1/2 cup
Sour cream2 Tbsp
Milk, treated with lactase enzyme1/2 cup
Sherbet1/2 cup
Aged cheese (such as blue, brick, cheddar, Colby, Swiss, Parmesan1-2 oz.
Processed cheese1 oz.

Tips for adding lactose foods back after a lactose diet:

  • Gradually add small amounts of food and drinks that contain lactose to determine your tolerance level. You may be able to tolerate up to 1/2 cup of milk or the equivalent with each meal.
  • Drink milk in servings of one cup or less.
  • Try hard cheeses that are low in lactose, like cheddar.
  • Drink milk with a meal or with other foods.
  • Try yogurt or Greek yogurt with active cultures. You may be able to digest yogurt better than milk. Your own tolerance may vary depending on the brand. Frozen yogurt may not be tolerated as well as yogurt.
  • Substitute lactose-reduced dairy products and 100 percent lactose-free milk for regular dairy products. These products are located in the dairy section of most supermarkets.
  • The lactase enzyme is also available in liquid, tablet or chewable form. No prescription is needed and it can help you tolerate foods containing lactose. Take the enzyme with the lactose-containing food. Lactase will help you digest the lactose so your body can absorb it. Some over-the-counter enzyme products that are available include Lactaid®, Lactrace®, Dairy Ease®, and Sure-Lac®.
  • Many canned nutritional supplements (such as Ensure®, Boost®) are lactose-free. Product labels should be checked.

How can I maintain a balanced diet?

Milk and dairy products are a major source of calcium, an essential nutrient for the growth and repair of bones and teeth throughout life. Calcium is also essential for blood to clot normally, muscles and nerves to function properly, and the heart to beat normally.

People who are lactose-intolerant don't necessarily have to consume milk and dairy products to get the calcium they need to maintain proper nutrition.

If you have trouble consuming enough calcium-rich foods in your daily diet, talk to your healthcare provider or a Registered Dietitian about taking a calcium supplement. The amount of calcium you will need from a supplement will depend on how much calcium you are consuming through food sources.

The following foods contain calcium:

Sardines3 oz.325 mg
Spinach (cooked)1 cup240 mg
Broccoli (cooked)1 cup180 mg
Calcium-fortified orange juice8 oz.350 mg
Calcium-fortified soy or almond milk8 oz.300 mg
Dried beans (cooked)1 and 1/2 cup150 mg
Tofu1/2 cup250 mg

Last reviewed by a Cleveland Clinic medical professional on 12/02/2019.


  • National Institute of Diabetes and Digestive and Kidney Diseases. ( Accessed 1/3/2020.
  • Nutrition Care Manual. ( Accessed 1/3/2020.

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