Lactose Intolerance

In Children, Babies And Infants

About Lactose intolerance in children and symptoms of lactose intolerance, the three types of lactose intolerance and foods containing lactose plus test for lactose intolerance.

Lactose intolerance means that children are hypersensitive to the milk sugar lactose but not allergic.

Sometimes allergy and other hyper sensitivities give the same symptoms, but being allergic to the cow milk protein called casein can give more severe symptoms.

The protein casein is in all milk products, and you can be allergic to the protein as a child and as an adult.

The symptoms can be similar to the ones you get with lactose intolerance, but often with additional problems like throwing up, eczema and breathing problems.

If your child has symptoms that is similar to lactose intolerance, you need to see the doctor.

Blood tests and other tests can confirm if the symptoms are caused by allergy or hypersensitivity.

Lactose intolerance in children is not dangerous even if the problems can feel very uncomfortable.

If the child doesn’t eat food products with lactose, first of all regular milk from cows, you can avoid having problems with reactions.

However the milk sugar lactose is included in a variety of different food products such as: hot dogs, wieners and sandwich meats as well as in chips, muesli, bread, bread crumbs and margarine.

If your child has been diagnosed with lactose intolerance it is important to see a dietitian to get help to establish a lactose intolerance diet.

Reading food labels is significant when you are shopping for lactose free foods to keep your child free of symptoms.

Lactose intolerance in children can be congenital by birth and give symptoms already as a newborn baby, but it’s uncommon.

Congenital lactose intolerance usually is discovered already when the baby is newborn.

They need to get a special formula and later a lactose free or lactose reduced diet.

You can also have a variant of lactose intolerance in children which is called primary lactose intolerance.

The child usually tolerates foods which contain a small amount of the milk sugar lactose as in aged cheese, butter and certain margarines.

Temporary lactose intolerance in children can be a problem if the small intestine is damaged by some intestinal disease.

Lactose Intolerance Symptoms

These are the usual symptoms of lactose intolerance and problems children experience when they can’t tolerate the milk sugar lactose:

  • Stomach gases
  • Diarrhea
  • Stomach pain
  • Bloated stomach

These troubles can arise immediately or up to a few hours after eating or drinking foods that contain lactose.

How long time it takes before these symptoms are gone varies from one individual to another.

The 3 Forms Of Lactose Intolerance

  • Primary lactose intolerance

  • Temporary, so called secondary lactose intolerance

  • Congenital lactose intolerance

Primary Lactose Intolerance:

It’s the most common form in children.

The reason is that the body sometimes after early childhood, doesn’t make or makes less of the enzyme lactase that is digesting lactose.

The ability to continue to make the enzyme lactase after childhood varies and is decided hereditary in each individual.

Treatment if the child has primary lactose intolerance: It usually gets better after changing the diet.

Temporary, Secondary Lactose Intolerance:

The illness that’s causing the symptoms in children needs to be treated.

When the mucous membrane is healed, the child can eat lactose again.

Sometimes it’s enough with some extra calcium in the form of a tablet, if the child doesn’t eat milk products due to lactose intolerance.

Congenital Lactose Intolerance:

It’s very unusual and means that the body can’t form the enzyme lactase.

The congenital condition is hereditary and is discovered in newborn babies as soon as they start breast feeding or formula.

The baby has water thin diarrhea, when the baby is either breast feeding or getting formula.

Because of dehydration and weight reduction the situation can quickly be serious.

However, if the baby doesn’t get any lactose, the baby has no symptoms or problems.

Children born with congenital lactose intolerance must as a rule totally avoid lactose for during their entire life.

When should you seek medical help?


  • If you suspect that you baby or child has lactose intolerance you should contact the doctor or child care center right away.


What happens in the body with lactose intolerance in children?


  • Lactose intolerance means that you are hypersensitive to lactose the milk sugar found in milk.
  • Usual symptoms are gases, diarrhea and stomach pain.
  • Lactose intolerance is not dangerous and gives no complications.
  • The problems can be experienced as uncomfortable, but can most often be avoided by reducing the amount of lactose food products as milk yogurt sour cream and cheese.


Lactose is digested in the small intestine.

In the small intestine’s mucous membrane are several different kind of enzymes that are needed for digestion.

These enzymes split the food into pieces so nutrients that can be absorbed from most of the small intestine and then to be able to transported further into the body.

The enzyme that breaks down lactose the sugar in milk is called lactase.


  • If the body is missing or have too little of this enzyme all of the lactose you get through the food isn’t digested in the small intestine.
  • It is left behind in the intestine and absorbs water both in the small intestine and the colon.
  • This can make the child get diarrhea or loose stools.
  • In the colon the lactose in attacked by bacteria which creates gases.


The ability to digest lactose can get reduced a lot without giving any problems.

The reduction can continue throughout life and it’s ability you can never get back.

Problems with primary lactose intolerance in children is most often showing up during the teenage years.

Secondary lactose intolerance can be acquired if the small intestine’s mucous membrane is hurt by an intestinal illness.

If the mucous membrane is damaged it affects the ability to form lactase.

Intestinal illnesses can be these reasons:


  • untreated gluten intolerance
  • inflammations in the intestine
  • parasite infections or other strong infections of the intestines.


When the illness is treated and the damage to the intestine is healed children can most often tolerate lactose again.

The ability to form enough of the enzyme lactase after early childhood varies between different groups of population.

For example most children in Sweden tolerate lactose, but if you have your origin in Finland or in a country outside of Northern Europe or North America, you are at an increased risk of getting lactose intolerant.

The reason is that in those countries it is common that the ability to form lactase is reduced by age.

Primary lactose intolerance in children means most often that the intolerance is increasing with age and some can be forced to almost stop consuming food products with lactose.

For most it is most often enough to reduce the intake of lactose by drinking lactose reduced milk instead of regular milk.

And every day life is seldom affected more than that.

Test For Lactose Intolerance


If you think your child has problems that indicate lactose intolerance, a test for lactose intolerance is should be made by a doctor.

Doctors have several different methods they can use to help them make the right diagnose.

Exclusion Methods:

The child usually gets to start with completely excluding milk products from his diet during four weeks.

If the problems then disappear and start to come back when the child is starting with milk products again, it can either be lactose intolerance or cow milk protein allergy.

If the child has no problems after a month with a diet that includes little lactose but normal amount of milk protein for example hard aged cheese the doctor may do another test.

Lactose Load.

If the exclusion methods can’t give a sure answer the doctor may examine with a so called lactose load

It is done in a hospital or a clinic.

The examination involves that the child drinks a lactose solution and then the child has to have a blood sample.

If somebody is lactose intolerant, problems like stomach pain and gases can come instantly or within a couple of hours.

When doing a lactose load you can’t eat or drink other than water at least 10 hours before the test.

Making the test with blood sample you leave first a blood sample in the morning at the hospital lab.

After that you get to drink a solution containing lactose and then leave blood samples with 15 minutes interval during one and half to two hours.

The blood tests show how well lactose is splitting in the small intestines.

Exhale Test

Lactose load can also be done as a breathing test so called exhale test which is easier for children who don’t accept blood tests easily.

The test is done in the hospital as well.

Both before and after drinking the lactose solution the amount of hydrogen is measured in the exhaled air with a special apparatus.

With lactose intolerance in children it is more hydrogen in the exhaled air after that they have had the drink with lactose solution, than before they had the drink.

Genetic Test

Doctors also sometime want to make a genetic test with a blood sample that is done at the clinic’s lab.

The test is done if the child has for example close relatives which have lactose intolerance and can either confirm or exclude ones ability to form lactase because of hereditary reasons is going to diminish.

The test functions only if you have European origin.

This test doesn’t say anything about the ability to split lactose at the moment and therefore doesn’t show if one is lactose intolerant or not, but the test result can help the doctor to make the right diagnosis.

Spectroscopic Examination.

If the doctor suspects that the problems can be the cause of some other illness, he can sometimes do spectroscopic examination of the small intestine.

It is done at the hospital with nothing to eat or drink during at least six hours before the examination.

During the examination a small tube is brought down through the mouth down to the stomach and then further to the upper part of the small intestine.

Using a small camera in the tube the doctor can look at the mucous membrane of the small intestine and take small samples of it, which are later examined in a microscope.

In the samples can sometimes the activity of lactase be measured.

If the doctor suspects temporary/secondary lactose intolerance this examination will help him make the correct diagnosing for example gluten intolerance.

Acknowledgment: Olle Hernell, Professor of Pediatrics, Norrlands University Hospital, Umea, Sweden

Acknowledgement: Henrik Sjovall, Doctor, Professor of Gastro-Intestinal Diseases, Sahlgrenska University Hospital, Gothenburg, Sweden

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