Lactose intolerance means your 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, your child may have unpleasant symptoms after eating or drinking milk products. These symptoms include bloating, diarrhea, and gas.

Lactose intolerance is different than having a food allergy to milk.

Lactose intolerance happens when the small intestine doesn't make enough of an 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 an infection.
• An injury to the small intestine.
• A 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.

Lactose intolerance can happen to anyone. But your child is more at risk for lactose intolerance if your child:

• Is a baby who was born too early (premature). This type of lactose intolerance is often a short-term problem that goes away.
• Is of African American, Ashkenazi Jewish, Mexican American, American Indian, or Asian American heritage.
• Has a family history of lactose intolerance. Symptoms may occur during the teen or adult years.

Symptoms often begin to appear after age 5, but they can start as early as age 2.

Symptoms begin about 30 minutes to 2 hours after having foods or drinks that have 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, which happens more often in teens.

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

Other health problems can cause symptoms similar to lactose intolerance. Always see your child's doctor for a diagnosis.

Your child's doctor will do a physical exam and ask about your child's 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. Your child's urine is checked for glucose levels. This test is less common than the hydrogen breath test.
• Hydrogen breath test. Your child drinks a liquid that has a lot of lactose. Your child's breath is then checked at regular times to measure the amount of hydrogen. High levels of hydrogen mean your child is lactose-intolerant.
• Stool acidity test. This test is used for babies and young children. It checks how much acid is in the stool. If your child is not digesting lactose, the stool will have lactic acid, glucose, and other fatty acids.
• In some cases, a small bowel biopsy (sample) is sent for testing.

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 doctor may also suggest that 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 your child should not eat.
• Have milk and milk products with other foods. You may find your child has fewer symptoms if your child has 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 doctor if your child should take a lactase pill or lactase drops when having milk products.

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

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 your child 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:

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. But it's important to keep children, especially small children, from eating fish bones. They can get stuck in the throat (esophagus).

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 doctor. The doctor may prescribe a calcium supplement if your child can't get enough calcium from foods alone.

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.

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

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 they 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. Read nutrition labels on foods. The bottom section of the label contains information on calcium and vitamin D.

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

The symptoms of lactose intolerance may look like symptoms of other disorders. Have your child checked by a doctor if your child has:

• Loose stool or diarrhea.
• Swelling or bloating.
• Belly pain.
• Other gastrointestinal (GI) symptoms.

• 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 an enzyme called lactase.
• Your child may have unpleasant symptoms such as bloating, gas, and an upset stomach after eating or drinking milk or milk products.
• Have your child see a doctor for a diagnosis.
• You can manage your child's symptoms by limiting foods that have lactose.
• Children and teens need calcium and vitamin D for bone growth and health. Read food labels so you can check that your child gets the right amount of these nutrients.
• Ask your doctor for help if you have concerns about making an eating plan for your child who has lactose intolerance.

Here are some tips to help you get the most from a visit to your child's doctor.

• Know the reason for the visit and what you want to happen.
• Before your visit, write down questions you want answered.
• At the visit, write down the name of any new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you for your child.
• Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.
• Ask if your child's condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if your child does not take the medicine or have the test or procedure.
• If your child has a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your child's doctor after office hours. This is important if your child becomes ill and you have questions or need advice.