Lactose tolerance test

Information about the lactose tolerance test.

This pamphlet provides information on the lactose tolerance test (the test is carried out to determine suspected lactose intolerance).


The test will be carried out at the Blodprøvetagningsambulatoriet (Outpatient Blood Test Department).

Your department will provide you with the time and date of the test.

Remember to bring your health card.

Why do I need the test?

We use a lactose tolerance test to determine whether you have 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

  • Avoid physical exercise on the day of the test.
  • Take any medication as usual.
  • You are not permitted to drink alcohol 24 hours before the test.
  • Do not eat for 8 hours before the test.
  • You may only drink water, tea and coffee (without sugar and milk) until two hours before the test.
  • You may drink water until one hour before the test.
  • You may not smoke tobacco or use nicotine products two hours before the test.
  • 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 finger or ear at the beginning of the test.
  • You will then be asked to drink a solution that contains lactose. The solution tastes sweet.
  • It is important that you drink the entire solution within a short amount of time.
  • After consuming the water containing lactose, you should avoid drinking water for the duration of the test.
  • Blood samples will be taken from your ear or finger after 15 minutes, 30 minutes, 45 minutes and 60 minutes.
  • You should rest during the test.

Test results

You will receive the results of the test from the doctor who ordered it.


Contact your department to schedule a new appointment.


Prøvetagningsambulatoriet, Hvidovre Hospital
Afsnit 130, Center 1
Kettegård Alle 30
2650 Hvidovre

The Illustration shows outpatient blood test department in Center 1 on a map
The Outpatient Blood Test Department in Center 1 in orange at Hvidovre Hospital.