Lactose tolerance test - children

Information about the lactose tolerance test for children.

This pamphlet provides information on the lactose tolerance test. The test is carried out in connection with suspected lactose intolerance.

The pictures shows a child playing with toys

Time and place

The test will take place at the Prøvetagningsambulatorie (Outpatient Test Department). Your child’s department will inform you about the time of the test. Remember to bring your child's health card.

Why does my child need the test?

We use a lactose tolerance test to determine whether your child has a reduced ability to break down lactose. Lactose is a type of sugar found in milk. A body’s inability to break down lactose can result in stomach pains and possibly diarrhea after ingesting milk. By measuring the conversion of a given quantity of lactose, we can determine whether there is a reduced ability to degrade lactose.

Preparing for the test

  • Your child must avoid physical exercise on the day of the test.
  • Your child should continue to take any medication they are on.
  • Your child may not eat 8 hours before the test.
  • Your child may only drink water, coffee and tea (without sugar and milk) until two hours before the test.
  • Your child may drink water until one hour before the test.
  • Your child should rest in an upright position for at least 15 minutes before the test.

If you have any questions, please contact the doctor or department that has ordered the test.

About the test

  • A blood sample will be taken from your child’s ear at the start of the test.
  • The child will then be asked to drink water that contains lactose. The amount depends on your child's weight, but max. 400 ml. The taste is a bit sweet.
  • It is important that your child drinks all the water.
  • After your child has consumed the water containing lactose, they should avoid drinking water for the duration of the test.
  • Blood samples will be taken from the ear after 15 minutes, 30 minutes, 45 minutes and 60 minutes.

Is the test painful?

Apart from the blood samples, there is no other pain in connection with the lactose tolerance test. However, the consumption of lactose may result in stomach complaints like cramps and diarrhea.

How long does the test take?

The test takes about two hours. Afterwards, your child can eat and drink as usual and you can go home.

Test results

You will be given the test results by the doctor who ordered the test.


If you need to cancel or reschedule, contact the department your child is connected to.