Approximately 65% of people worldwide have lactose intolerance.

You can get a hydrogen breath test, the gold standard for diagnosing lactose intolerance.

Try managing lactose intolerance by limiting your lactose intake and trying lactose-free products.

Lactose intolerance is a condition that results in uncomfortable digestive symptoms after you consume foods or drinks that contain lactose—or a sugar that is naturally found in dairy products. These uncomfortable digestive symptoms, such as bloating, gas, and diarrhea, are caused by lactose malabsorption, which means your small intestine cannot digest or break down all of the lactose you consume.

Approximately 65% of people in the world are lactose intolerant. However, this condition is most common in African Americans, Hispanics/Latinos, and Asians, and least prevalent in people of European descent.

Some people are born with lactose intolerance, while others develop the condition as they age.

When your small intestine does not make enough of the digestive enzyme lactase, you can develop lactose intolerance. Lactase is responsible for breaking down the lactose in the foods you eat so your body can absorb the nutrients. 

There are four types of lactase deficiency that could potentially lead to lactose intolerance:

When you have lactose intolerance, you will likely experience symptoms 30 minutes to 1 to 2 hours after consuming dairy products. The severity of your symptoms are influenced by how much lactose you consumed. In other words, having a bowl of ice cream or a glass or milk will affect you differently than cheese sprinkled on your salad.

Your lactose intolerance is also influenced by how much lactase you have in your body and how long it takes the food you ate to leave your small bowel. The most common signs and symptoms of lactose intolerance include:

Older research indicates that lactose intolerance also can potentially cause headaches, muscle pain, joint pain, mouth ulcers, urinary symptoms, and loss of concentration. Though, these symptoms are not very common.

Lactose intolerance is caused by lactose malabsorption, which occurs when your small intestine makes low levels of the enzyme lactase and can't digest all the lactose you eat or drink. When you have a lactase deficiency, your body doesn't produce enough lactase in order to digest the lactose in your foods and drinks.

While some people inherit the condition, you also can be at risk as you age as well as if you have certain medical conditions. Here are some of the more common risk factors for lactose intolerance.

Finding the root cause of a food intolerance like lactose intolerance is not an easy process, especially because the symptoms mimic those of other common gastrointestinal and bowel disorders. That said, there are several ways to diagnose lactose intolerance.

Conducting a hydrogen breath test (HBT) is currently considered the gold standard for diagnosing lactose intolerance. This is primarily due to the test's high sensitivity and specificity as well as the fact that it is an inexpensive test that is simple to use and non-invasive.

The test is based on the measurement of hydrogen exhaled every 30 minutes after taking lactose (usually 25 grams which is equivalent to about 500 milliliters of milk). When the hydrogen level in the exhaled air is 20 parts per million or greater than the baseline, the test is positive for lactose intolerance.

Sometimes a healthcare provider will have you follow an elimination diet where you avoid anything that contains lactose to see if your symptoms improve. They also may ask you to keep a journal of what you eat and any symptoms you experience. These two options will help your healthcare provider determine if you have lactose intolerance or not.

The lactose tolerance test evaluates your blood sugar levels after you drink a lactose solution. If your blood sugar doesn't rise significantly, it's a sign that you are lactose intolerant. This lack of elevation occurs because your body can't absorb the sugar building blocks if the lactose isn't broken down. During this test, your blood sugar levels are measured regularly over a two hour period while watching for symptoms like diarrhea or cramps.

While there’s no known cure for lactose intolerance, there are a number of things you can do to treat the condition. The first approach is to limit the amount of lactose you consume in a day's time. That said, it is important to note that it is rarely advised that you completely eliminate foods that include lactose.

Aside from the fact that dairy products contain important vitamins and minerals—like vitamin D, vitamin B12, magnesium, and calcium—most research indicates that people with lactose intolerance can consume about 12 grams of lactose, which is equivalent to about 1 cup of milk. Meanwhile, studies show that 18 grams of lactose can be tolerated when consumed with other foods or spread out in small amounts throughout the day.

There also is some limited evidence that gradually exposing your body to lactose could help your body adapt to it. In fact, one study indicates that consistent exposure could prompt your body to produce some lactase and reduce symptoms. Even though studies are limited, the results show promise.

Although there is no way to prevent yourself from developing lactose intolerance, there are things you can do to mitigate the symptoms. Aside from limiting dairy products in your everyday diet, you also can take lactase supplements to help you digest the lactose you consume. However, it is important to note that the effectiveness of these products vary widely.

There also is some limited evidence that probiotics and prebiotics may reduce symptoms of lactose intolerance. However, not all probiotics have the same impact. Bifidobacteria and Lactobacillus, which are often found in probiotic yogurts and supplements, have been shown to be the most effective.

You can even try using lactose-free products which are made lactose-free by removing the lactose during the manufacturing process. One well-known dairy brand is Lactaid, but plant-based milks—like cashew milk, almond milk, soy milk, and oat milk—are naturally lactose free. There are also a number of non-dairy products such as coconut yogurt, cashew cheese, and more. Talk to a healthcare provider to determine which products are right for you.

Having lactose intolerance also can put you at risk for other conditions as well. For instance, there is some evidence that lactose intolerance is related to everything from osteoporosis to depression. Here is a closer look at several of the more studied comorbid conditions.

If you have been diagnosed with lactose intolerance, you likely experience uncomfortable digestive symptoms when you eat dairy products. Fortunately, there are things you can do to address your condition and reduce your symptoms.

Aside from limiting how much dairy you eat, you can also try spacing its consumption out throughout the day as well as eat dairy with other foods to minimize your reaction. There also are supplements you can take to help your body digest the lactose you eat as well as products that are made without lactose.

Finding out how much dairy you can eat during a day as well as whether or not lactase supplements will work for you will take some trial and error. While this may take some time, with the help of your healthcare provider, you should be able to find an approach that works for you. They also can help monitor important vitamins and minerals—such as vitamin D, calcium, vitamin B12, and magnesium—to ensure you are getting the nutrients you need.

Dietary supplements are minimally regulated by the FDA and may or may not be suitable for you. The effects of supplements vary from person to person and depend on many variables, including type, dosage, frequency of use, and interactions with current medications. Please speak with your healthcare provider or pharmacist before starting any supplements.

Read more:

Was this page helpful?

Thanks for your feedback!

Tell us why!

16 Sources

Health.com uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

National Library of Medicine. Lactose intolerance.

National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms and causes of lactose intolerance.

American College of Gastroenterology. Lactose intolerance.

Fassio F, Facioni MS, Guagnini F. Lactose maldigestion, malabsorption, and intolerance: A comprehensive review with a focus on current management and future perspectives. Nutrients. 2018;10(11):1599. doi:10.3390/nu10111599

National Library of Medicine. Causes and diagnosis of lactose intolerance.

University of Virginia. Got lactase? A clinician's guide to lactose intolerance.

Szilagyi A. Adult lactose digestion status and effects on disease. Can J Gastroenterol Hepatol. 2015 Apr;29(3):149-56. doi:10.1155/2015/904686

Szilagyi A. Adaptation to lactose in lactase non-persistent people: Effects on Intolerance and the relationship between dairy food consumption and evalution of diseases. Nutrients. 2015 Aug 13;7(8):6751-79. doi:10.3390/nu7085309

Szilagyi A, Ishayek N. Lactose intolerance, dairy avoidance, and treatment options. Nutrients. 2018;10(12):1994. doi:10.3390/nu10121994

Leis R, de Castro MJ, de Lamas C, Picáns R, Couce ML. Effects of prebiotic and probiotic supplementation on lactase deficiency and lactose intolerance: A systematic review of controlled trials. Nutrients. 2020 May 20;12(5):1487. doi:10.3390/nu12051487

Dekker PJT, Koenders D, Bruins MJ. Lactose-free dairy products: Market developments, production, nutrition and health benefits. Nutrients. 2019;11(3):551. doi:10.3390/nu11030551

Mahato DK, Keast R, Liem DG, Russell CG, Cicerale S, Gamlath S. Sugar reduction in dairy food: An overview with flavoured milk as an example. Foods. 2020;9(10):1400. Published 2020 Oct 2. doi:10.3390/foods9101400

Schiffner R, Kostev K, Gothe H. Do patients with lactose intolerance exhibit more frequent comorbidities than patients without lactose intolerance? An analysis of routine data from German medical practices. Ann Gastroenterol. 2016;29(2):174-179. doi:10.20524/aog.2016.0009

National Institute of Arthritis and Musculoskeletal and Skin Diseases. What people with lactose intolerance need to know about osteoporosis.

Ojetti V, Nucera G, Migneco A, Gabrielli M, Lauritano C, Danese S, Zocco MA, Nista EC, Cammarota G, De Lorenzo A, Gasbarrini G, Gasbarrini A. High prevalence of celiac disease in patients with lactose intolerance. Digestion. 2005;71(2):106-10. doi:10.1159/000084526

Ledochowski M, Sperner-Unterweger B, Fuchs D. Lactose malabsorption is associated with early signs of mental depression in females: a preliminary report. Dig Dis Sci. 1998 Nov;43(11):2513-7. doi:10.1023/a:1026654820461