Tuberculin Skin Test (TST)

The Tuberculin Skin Test (TST or Mantoux test) is a test used to see whether a person has tuberculosis (TB) infection.

TB infection (also known as latent TB infection or 'sleeping' TB) is when you have TB germs in your body, but they are not making you sick. Your body's immune system is stopping the germs causing any damage. There are no symptoms with TB infection and the germs cannot be passed to other people.

TB infection is different from TB disease which is when TB germs wake up or increase in number and make you sick and able to pass the germs on to other people. If the TST shows you have TB infection, your doctor can prescribe medicine to stop TB disease.

More information about TB infection can be found here: TB infection

Last updated: 24 January 2025

How is the TST performed?

A TST involves a small injection of tuberculin (purified protein derivative) into the forearm. After a few days, a red mark or lump may appear, or there may be no change at all. A specialist TB nurse needs to look at the place where the injection was done 48-72 hours after the test.

Before you have a TST

There are some health conditions and medicines that can affect your test result. Tell your nurse or doctor if you:

have any immune weakening illnesses such as HIV, cancer, or kidney disease,
take medicine that affects your immune system such as steroids (e.g. prednisone), or chemotherapy (cancer drugs)
have had a fever (>38° C) or infection in the past month, such as the flu, measles, or a chest infection,
have received any vaccines in the past month,
have had TB in the past, contact with someone with TB, have received the TB vaccine (BCG),
have previously had a TST.

After you have a TST

Do not scratch the injection site.
Do not cover the site with any dressing, band aid, cream, or ointment.
If any blisters occur do not break them.
You may continue all normal activities including work, sports, bathing, and showering.

Make sure the injection site is looked at by a specialist nurse or doctor 48-72 hours after the TST was done so any reaction can be assessed and recorded. If the TST is positive, you may need some follow-up tests. The nurse or doctor will explain the result and whether any more tests or treatment is needed.