BACK TOTOP Browse A-ZSearchBrowse A-ZABCDEFGHIJKLMNOPQRSTUVWXYZ0-9 E-mail FormEmail ResultsName:Email address:Recipients Name:Recipients address:Message: Print-FriendlyBookmarksbookmarks-menuLactose intoleranceLactase deficiency; Milk intolerance; Disaccharidase deficiency; Dairy product intolerance; Diarrhea - lactose intolerance; Bloating - lactose intoleranceLactose is a type of sugar found in milk and other dairy products. An enzyme called lactase is needed by the body to digest lactose.Lactose intolerance develops when the small intestine does not make enough of this enzyme. Causes Babies' bodies make the lactase enzyme so they can digest milk, including breast milk.Babies born too early (premature) sometimes have lactose intolerance. Children who were born at full term often do not show signs of the problem before they are 3 years old.Lactose intolerance is very common in adults. It is rarely dangerous. About 30 million American adults have some degree of lactose intolerance by age 20.In white people, lactose intolerance often develops in children older than age 5. This is the age when our bodies may stop making lactase. In African Americans, the problem can occur as early as age 2. The condition is very common among adults with Asian, African, or Native American heritage. It is less common in people of northern or western European background, but still may occur. An illness that involves or injures your small intestine may cause less of the lactase enzyme to be made. Treatment of these illnesses may improve the symptoms of lactose intolerance. These may include:Surgery of the small intestine Infections in the small intestine (this is most often seen in children) Diseases that damage the small intestines, such as celiac sprue or Crohn disease Celiac sprueCeliac disease is an autoimmune condition that damages the lining of the small intestine. This damage comes from a reaction to eating gluten. This ...ImageRead Article Now Book Mark Article Crohn diseaseCrohn disease is a disease where parts of the digestive tract become inflamed. It most often involves the lower end of the small intestine and the be...ImageRead Article Now Book Mark Article Any illness that causes diarrheaBabies may be born with a genetic defect and are not able to make any of the lactase enzyme. Symptoms Symptoms often occur 30 minutes to 2 hours after having milk products. Symptoms may be worse when you consume large amounts.Symptoms include:Abdominal bloating Abdominal bloatingA swollen abdomen is when your belly area is bigger than usual.Read Article Now Book Mark Article Abdominal cramps Diarrhea Gas (flatulence) FlatulenceGas is air in the intestine that is passed through the rectum. Air that moves from the digestive tract through the mouth is called belching. Gas is ...ImageRead Article Now Book Mark Article Nausea Exams and Tests Other intestinal problems, such as irritable bowel syndrome, may cause the same symptoms as lactose intolerance.Irritable bowel syndromeIrritable bowel syndrome (IBS) is a disorder that leads to pain in abdomen and bowel changes. IBS is not the same as inflammatory bowel disease (IBD...ImageRead Article Now Book Mark Article Tests to help diagnose lactose intolerance include:Lactose-hydrogen breath test Lactose tolerance test Lactose tolerance testLactose tolerance tests measure the ability of your intestines to break down a type of sugar called lactose. This sugar is found in milk and other d...ImageRead Article Now Book Mark Article Stool pH Another method may be to challenge a patient with 25 to 50 grams of lactose in water. Symptoms are then assessed using a questionnaire.A 1 to 2 week trial of a completely lactose-free diet is also sometimes tried. Treatment Cutting down your intake of milk products that contain lactose from your diet most often eases symptoms. Also look at food labels for hidden sources of lactose in nonmilk products (including some beers) and avoid these.Most people with low lactase level can drink up to one half cup of milk at one time (2 to 4 ounces or 60 to 120 milliliters) without having symptoms. Larger servings (more than 8 ounces or 240 mL) may cause problems for people with the deficiency.Milk products that may be easier to digest include:Buttermilk and cheeses (these foods contain less lactose than milk) Fermented milk products, such as yogurt Goat's milk Aged hard cheeses Lactose-free milk and milk products Lactase-treated cow's milk for older children and adults Soy formulas for infants younger than 2 years Soy or rice milk for toddlers You can add lactase enzymes to regular milk. You can also take these enzymes as capsules or chewable tablets. There are also many lactose-free dairy products available.Not having milk and other dairy products in your diet can lead to a shortage of calcium, vitamin D, riboflavin, and protein. You need 1,000 to 1,500 mg of calcium each day depending on your age and sex. Some things you can do to get more calcium in your diet are:Take calcium supplements with Vitamin D. Talk to your health care provider about which ones to choose. Eat foods that have more calcium (such as leafy greens, oysters, sardines, canned salmon, shrimp, and broccoli). Drink orange juice with added calcium. Outlook (Prognosis) Symptoms most often go away when you remove milk, other dairy products, and other sources of lactose from your diet. Without dietary changes, infants or children may have growth problems.If the lactose intolerance was caused by a temporary diarrheal illness, levels of lactase enzyme will return to normal within a few weeks. When to Contact a Medical Professional Call your provider if: You have an infant younger than 2 or 3 years old who has symptoms of lactose intolerance. Your child is growing slowly or not gaining weight. You or your child has symptoms of lactose intolerance and you need information about food substitutes. Your symptoms get worse or do not improve with treatment. You develop new symptoms. Prevention There is no known way to prevent lactose intolerance. You can prevent symptoms by avoiding foods with lactose.Open ReferencesReferencesHöegenauer C, Hammer HF. Maldigestion and malabsorption. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 104.National Institute of Diabetes and Digestive and Kidney Diseases website. Definition & facts for lactose intolerance. www.niddk.nih.gov/health-information/digestive-diseases/lactose-intolerance/definition-facts. Updated February 2018. Accessed May 28, 2020.Semrad CE. Approach to the patient with diarrhea and malabsorption. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 131.AllVideoImagesTogDigestive system organs - illustration The digestive system organs in the abdominal cavity include the liver, gallbladder, stomach, small intestine and large intestine.Digestive system organsillustrationDigestive system organs - illustration The digestive system organs in the abdominal cavity include the liver, gallbladder, stomach, small intestine and large intestine.Digestive system organsillustration Tests for Lactose intolerance Lactose tolerance testsRelated Information Enzyme(Special Topic)Abdominal bloating(Symptoms)Abdominal pain(Symptoms)Vitamin D(Nutrition)Protein in diet(Nutrition)Celiac disease – sprue(Condition)Viral gastroenteritis (stomach flu)(Condition)Enteritis(Condition)Diarrhea - what to ask your health care provider - adult(Doctor Questions)Diarrhea - what to ask your doctor - child (Doctor Questions)Vitamins and Phytonutrients(In-Depth) Review Date: 4/30/2020 Reviewed By: Bradley J. Winston, MD, board certified in gastroenterology and hepatology, Washington, DC. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- © 1997- All rights reserved. A.D.A.M. content is best viewed in IE9 or above, Firefox and Google Chrome browser.Content is best viewed in IE9 or above, Firefox and Google Chrome browser.