Tuberculin Skin Tests

A tuberculin skin test is done to see if you have ever had tuberculosis (TB) (Mycobacterium tuberculosis). It is done by putting a small amount of TB protein (antigens) under the top layer of skin on your inner forearm. If you have ever been exposed to the TB bacteria, your skin will react to the antigens by developing a firm red bump at the site within 2 days.

The Mantoux skin test uses TB antigens called purified protein derivative (PPD). The test cannot tell if the infection is active or inactive (latent).

The Mantoux test uses a measured amount of PPD in a shot that is put under the top layer of skin on your forearm. A Mantoux test is a good test for a TB infection. It is often used when symptoms, screening, or testing, such as a chest X-ray, show that a person may have TB.

A tuberculin skin test cannot tell how long you have been infected with TB or if the infection can be passed to others (active TB).