health information
Information about the Tuberculin Skin Test
What is a tuberculin skin test?
A tuberculin (Mantoux) skin test is done to see if you have been infected with the TB germ.
It does not tell when you were infected.
It tests for latent tuberculosis (TB) infection, not for active TB disease.
What is latent TB infection?
TB is caused by a germ called Mycobacterium tuberculosis. While it is often found in the
lungs, it can also be found in other parts of the body.
Latent TB infection is when the TB germs are not growing (are inactive). Latent TB
infection does not make you feel sick. You can’t spread latent TB infection to others.
Many people have latent TB infection. Only 10% will develop active TB disease as long as
they stay healthy.
What is active TB disease?
Active TB disease means that the TB germs are growing, which means you can spread TB
disease to other people. When you have active TB disease, you usually feel sick (for
example, have a cough, fever, lose weight, have night sweats).
How does the test work?
You will come for two appointments that are 2 to 3 days apart.
First appointment: A testing solution is injected under the skin on your forearm.
Second appointment: A nurse that has been trained to read skin reactions will check your
o There may be no change in the area the injection was given in.
o There may be a hard swelling surrounded by a red area. The nurse will measure the
reaction to decide if it is negative or positive.
What do the results mean?
A negative skin test usually means that you are not infected with the TB germ. Sometimes
the test needs to be done again later.
A positive skin test usually means that you have the latent TB infection. You can also have
a positive test if you had a TB vaccine (BCG) or were infected before with a germ that is
like the TB germ.
If you have a positive skin test you will have a chest x-ray done and maybe other tests. You
will be referred to your family doctor or Tuberculosis Services.
605948 &copy; Alberta Health Services, (2011/11)
Is the skin test safe?
The test is safe for most people, including pregnant women or people that have had the
BCG vaccination.
Do not have the test if you have:
• symptoms of TB disease
• a history of a positive TB skin test
• been treated for TB
Are there any side effects?
Most people have no side effects.
There may be some bruising, itching, or discomfort around the test site.
Even though allergic reactions are rare, we ask that you stay for 15 minutes after the test.
How do I care for the test site?
Pat your arm dry after you have a bath or shower.
• cover the site with a bandage
• scratch, wipe, or scrub the skin around the test site
• put cream or lotions on the test site
Put a cold compress on the test site if it itches.
Please come back to have the test reaction read, even if you don’t see a reaction on
your arm.
Your appointment is on _________________________________ at ________________
Keep a copy of your test results. You may have to show these results to your healthcare
provider or your employer one day.
If you have questions or concerns about the skin test, call the clinic at:
This material is for information purposes only. It should not be used in place of medical advice, instruction
and/or treatment. If you have questions, speak with your doctor or appropriate healthcare provider.