Skip to main content
menu
URMC / Encyclopedia / Content

What is Lactose Intolerance?

Lactose intolerance is when the body can't easily break down or digest lactose. Lactose is a sugar found in milk and milk products.

If your child is lactose intolerant, he or she may have unpleasant symptoms after eating or drinking milk products. These symptoms include bloating, diarrhea, and gas.

Lactose intolerance is different from having a food allergy to milk, and different from cow's milk protein intolerance.

What causes Lactose Intolerance?

Lactose intolerance happens when the small intestine doesn't make enough of a digestive juice, or enzyme, called lactase. Without enough lactase, the body can't break down or digest lactose.

Lactose intolerance can happen to both children and adults. Some common causes include:

  • Digestive diseases or infection

  • Injury to the small intestine

  • Family history of lactose intolerance. In these cases, over time the body may make less of the lactase enzyme. Symptoms may occur during the teen or adult years.

  • A baby being born too early, also called a premature baby. This type of lactose intolerance is often a short-term problem that goes away.

In very rare cases, some newborns can't make any lactase from birth, known as congenital lactase deficiency.

Who is at risk for Lactose Intolerance?

Your child is more at risk for lactose intolerance if he or she:

  • Is a baby who was born too early, also called a premature baby. This type of lactose intolerance is often a short-term problem that goes away.

  • Is African American, Jewish, Mexican American, American Indian, or Asian American

  • Has a family history of lactose intolerance. Symptoms may occur during the teen or adult years.

What are the symptoms of Lactose Intolerance?

Symptoms often begin to appear in white children after age 5. They appear in African-American children as young as 2 years old.

Symptoms begin about 30 minutes to 2 hours after having foods or drinks containing lactose. Each child's symptoms may vary. Symptoms may include:

  • Upset stomach or nausea

  • Cramps

  • Bloating

  • Belly (abdominal) pain

  • Gas

  • Loose stool or diarrhea

  • Vomiting, happens more often to teens

How severe your child's symptoms are will depend on how much lactose he or she has had. It will also depend on how much lactase your child's body makes.

The symptoms of lactose intolerance may look like other health conditions. Always see your child's healthcare provider for a diagnosis.

How is Lactose Intolerance diagnosed?

Your child's healthcare provider will give your child a physical exam and take a health history.

Your child may need to be tested. The most common tests used to check how lactose is absorbed in the digestive system include:

  • Lactose tolerance test. This test checks how lactose is absorbed by your child's digestive system. After fasting, your child drinks a liquid that has lactose. The loose stools are then tested for lactose for the next 24 hours.

  • Hydrogen breath test. Your child drinks a liquid that has a lot of lactose. The breath is then checked at regular times to measure the amount of hydrogen. High levels of hydrogen mean your child is lactose intolerant.

  • Biopsy / disaccharidase test. This test involves undergoing an upper endoscopy and taking a small sample from the first part of the small intestine for enzyme analysis.

How is Lactose Intolerance treated?

Treatment will depend on your child's symptoms, age, and general health. It will also depend on how severe the condition is.

No treatment will help your child's body make more lactase. But you can manage your child's symptoms with a diet that limits lactose. Your child may not have to stop eating all foods with lactose. Your child's healthcare provider may also suggest your child take lactase enzymes. They are sold over the counter.

Here are some tips for managing lactose in your child's diet:

  • Start slowly. After a week of limiting foods with lactose, try adding small amounts of milk or milk products back to your child's diet. Watch to see if your child has any symptoms. Note which foods your child can handle, and which foods he or she should avoid.

  • Have milk and milk products with other foods. You may find your child has fewer symptoms if he or she takes milk or milk products with meals. Have your child try eating cheese with crackers. Or let your child have milk with cereal.

  • Choose dairy products with naturally lower levels of lactose. These include hard cheeses and yogurt.

  • Look for lactose-free and lactose-reduced milk and milk products. These can be found at many food stores. They are the same as regular milk and milk products. But they have the lactase enzyme added to them.

  • Ask about lactase products. Ask your child's healthcare provider if your child should take a lactase pill or lactase drops when having milk products.

Talk with your child's provider about what products or diet changes may help your child. You may also find it helpful to see a registered dietitian.

Calcium

Children and teens who are lactose intolerant may have little or no milk in their diet. But milk and dairy products are a major source of calcium. If your child is lactose intolerant, be sure that he or she gets enough calcium. Calcium is needed for growing and repairing bones throughout life. Calcium may also help prevent some diseases.

The amount of calcium your child needs will vary by age:

Child's age Recommended dietary amount of calcium (mg per day)
0 to 6 months 200 mg
6 months to 1 year 260 mg
1 to 3 years 700 mg
4 to 8 years 1,000 mg
9 to 18 years 1,300 mg

Many nondairy foods are high in calcium, including:

  • Green vegetables, such as collard greens, turnip greens, broccoli, and kale

  • Fish with soft, edible bones, such as salmon and sardines

Other nondairy foods that are good sources of calcium include:

  • Tofu

  • Orange juice with added calcium

  • Soy milk with added calcium

  • Breakfast cereals with added calcium

Always talk with your child's healthcare provider. Your child's provider may prescribe a calcium supplement if your child can't get enough calcium from his or her diet.

Vitamin D

Vitamin D is needed for the body to absorb calcium. It's important that your child's diet has enough vitamin D. Sources of vitamin D include eggs and liver.

Children under 1 year old should have a vitamin D supplement of 400 IU a day. Children over 1 year old should have 600 IU of vitamin D a day.

What are the complications of Lactose Intolerance?

Lactose intolerance won't hurt your child's body. The symptoms are unpleasant, but they are not serious.

Living with Lactose Intolerance

Lactose intolerance can cause unpleasant symptoms. But in most cases you don't need to remove all foods with lactose from your child's diet. By watching your child's symptoms, you can find out which foods he or she can handle. You can also tell which foods your child should avoid.

When foods are removed from your child's diet, you must replace them with other foods that offer needed nutrients. Also make sure that your child has enough calcium and vitamin D.

Talk with your child's provider about what products or diet changes may help your child. You may also find it helpful to see a registered dietitian.

When should I call my child's healthcare provider?

The symptoms of lactose intolerance may look like symptoms of other disorders. Have your child checked by his or her healthcare provider if your child has:

  • Loose stool or diarrhea

  • Swelling or bloating

  • Belly pain

  • Other GI or gastrointestinal symptoms

Key points about Lactose Intolerance

  • Lactose intolerance is when your child's body can't easily break down, or digest, lactose. Lactose is a sugar found in milk and milk products.

  • It happens when the small intestine doesn't make enough of a digestive juice, or enzyme, called lactase.

  • Your child may have uncomfortable symptoms after eating or drinking milk or milk products.

  • You can control your child's symptoms by limiting foods that have lactose.

  • Make sure your child sees a healthcare provider.

  • Children and teens need calcium and vitamin D for bone growth and health.

Medical Reviewers:

  • Adler, Liora C, MD
  • Chan, Albert, MD
  • Chan,Albert, MD
  • Watson, L Renee, MSN, RN