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Tuberculin skin test
Also called the Mantoux skin test
Key points about the tuberculin skin test
- A tuberculin skin test is used to find out if you have tuberculosis (TB) infection.
- TB infection is when you have TB bacteria in your body. You can have an infection but not be sick – this is called latent TB infection.
- You can be infected with TB by breathing in the bacteria if you’re in close contact with someone with TB disease, this is more common if you are from places with higher rates of TB.
- The test is done by injecting a small amount of liquid into the top layer of skin on your arm. Your arm is then checked after 2 to 3 days to see if there’s been a reaction to the injection.
- The injection doesn’t contain live bacteria and can’t give you TB.
A tuberculin skin test, also called the Mantoux test, is done to see whether you have tuberculosis (TB) infection. TB infection is when you have TB bacteria in your body. You can be infected without the bacteria making you sick – this is also called latent TB infection. It’s different to active TB disease as you don’t have any symptoms and you can’t spread TB to other people.
The tuberculin skin test contains purified protein from TB bacteria that have been killed by heating. The test causes a skin reaction if you have latent TB infection, such as from being in close contact with someone with TB disease or being in a place with high rates of TB.
If the test is positive you'll need further assessment to decide if you have a TB infection. If you do, your healthcare provider will discuss whether there is a need to treat this or not. Medicine is available to stop latent TB from turning into TB disease.
In Aotearoa New Zealand, you may be screened for latent TB infection if:
- you've been in contact, or likely to have been in contact, with someone with TB, or
- you’re at risk of catching TB and need protection against the disease (with BCG vaccination), or
- your work requires TB testing.
For most people screening is done using a blood test called Quantiferon TB Gold (also known as interferon gamma release assay or IGRA), however sometimes a tuberculin skin test is done instead. Children under the age of 2 who are tested for latent TB should have a tuberculin skin test rather than the IGRA blood test.
You may be more at risk of getting TB if you:
- are in close contact with a person with active TB disease
- were born in a country with higher rates of TB
- travelled to or lived for more than 1 month in a country with higher rates of TB
- have a weakened immune system, such as being HIV-positive
- live or work, or are going to live or work, in certain institutional settings, eg, healthcare facilities.
Read more about tuberculosis (TB).
Before the test
Before you have the test, tell the person doing the test if any of the following apply to you as these can affect the test results:
- You have a weakened immune system, eg, because of HIV, cancer, or kidney disease.
- You take medicine that affects your immune system such as steroids (eg, prednisone), or chemotherapy (cancer drugs).
- You’ve had a fever (>38° C) or infection in the past month, such as the flu, measles, or a chest infection.
- You’ve had any vaccines in the past month.
- You’ve had tuberculosis (TB) in the past, contact with someone with TB, or you’ve had the TB vaccine (BCG).
- You’ve had a tuberculin skin test in the past.
The test
The tuberculin skin test involves injecting a small amount of fluid that contains purified TB protein, called tuberculin, just under the skin of your forearm. This is done by a specially trained laboratory technician using a small needle and syringe.
The test doesn’t contain live bacteria and can’t cause tuberculosis (TB).
After the test
- You’ll need to stay at the lab for 20 minutes in case you have an unwanted reaction to the tuberculin (this is rare).
- You may get a small blister at the injection site, but this usually disappears within 30 minutes.
- Sometimes the site may bleed a little and the nurse may cover it with a cotton wool swab. This can be removed after 10 minutes and thrown away.
- Don’t apply creams or band-aids to the injection site and avoid scratching it. To relieve any itchiness, apply ice or something cold to the area.
- You can continue your normal activities after having the test including showering, swimming and sport.
- You’ll need to go back to the lab after 2 to 3 days so that the injection site can be checked to see if the test is positive or negative (see the section below). You might see a red spot or bump, or it might look the same as before the test.
Image credit: Bruce Blausen Wikimedia Commons
Two to 3 days after having the tuberculin skin test, the laboratory technician will measure your skin’s reaction (size of the bump) to the tuberculin. If more than 3 days have passed before you get your injection site checked, the assessment won’t be reliable and you’ll need to have another skin test.
Interpretation of the test result depends on certain things, including whether:
- you’ve been in contact with somebody who has tuberculosis (TB)
- you’ve previously had the TB vaccine
- you’re a young child
- you have a condition that affects your immune system, such as HIV.
If your tuberculin test is negative (that is, the bump is below a certain size), you may be advised:
- to have a repeat test at a later date
- to have a BCG vaccination to protect against TB, or
- that no further follow-up is needed.
If your injection site is positive (the bump is above a certain size), you may be advised:
- to have treatment for latent TB
- to have further tests for active TB disease, such as an X-ray or blood or sputum tests
- to avoid further tuberculin skin tests
- to consult with your usual healthcare provider, or
- that no further follow-up is needed.
The tuberculin skin test is simple and safe and side effects are uncommon.
There’s a very small risk of severe redness and swelling in your arm, especially if you’ve had a previous positive reaction to the test. In general, people who’ve had a positive tuberculin skin test in the past shouldn’t have the test again.
The following links have more information on the tuberculin skin test. Be aware that websites from other countries may contain information that differs from New Zealand recommendations.
Brochures
What you need to know about the TB skin test(external link) Centers for Disease Control and Prevention, US also available in Spanish(external link), Tagalog(external link), Vietnamese(external link)
Translated tuberculosis fact sheets – tuberculin skin test(external link) Queensland Government, Queensland Health, Australia (Factsheet about tuberculin skin testing (Mantoux test) in Arabic, Burmese, Traditional Chinese, Dari, English, Farsi, Indonesian, Japanese, Korean, Pidgin, Thai, Torres Strait Creole, and Vietnamese.)
Tuberculin skin test (TST)(external link) NSW Government, NSW Health, Australia with translated factsheets, including Hindi(external link), Samoan(external link) and Tongan(external link)
References
- Tuberculin skin test (TST)(external link) NSW Health, Australia, 2025
- Latent tuberculosis(external link) Auckland HealthPathways, NZ, 2024
- Clinical testing guidance for tuberculosis – tuberculin skin test(external link) Centers for Disease Control and Prevention, US, 2025
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Credits: Healthify editorial team. Healthify is brought to you by Health Navigator Charitable Trust.
Reviewed by: Dr Sara Jayne Pietersen, FRNZCGP, Auckland
Last reviewed:
