Tuberculosis Testing

Healthcare provider writing on clipboard while patient rests arm on table.

Tuberculosis (TB) is a bacterial disease that spreads through the air. A person with TB of the throat or lungs who coughs, speaks, or sings can unknowingly spread the bacteria into the air. Uninfected people nearby can breathe in the TB bacteria and be infected.

TB can cause serious health problems. To protect your health, get tested.


If you have active TB disease or simply test positive for TB infection, you must see a healthcare provider for an exam and treatment.

Who should be tested?

Anyone can be exposed to TB. But healthcare providers, homeless people, and people coming from countries with high TB rates are more likely to be exposed to it. Older adults and people with HIV and AIDS are less able to fight off infections. They are also more likely to get TB. If you’re at risk for exposure, get tested regularly.

TB tests

  • Skin test. The TB skin test tells you if the TB bacteria are in your body. A small amount of solution is put under the skin with a needle. This is done to see if a reaction occurs, such as a hard, red bump.

  • Blood test. A small amount of blood is drawn and sent to a lab for testing.

  • Other tests. If you are being evaluated for active TB, a sample may be taken of the mucus that comes up when you cough (sputum). Or some other tissue or body fluid sample may be taken. It is then tested for TB.

Getting your TB test results

After the placement of a TB skin test, 2 to 3 days later you’ll need to return to the office to get the test read. Be sure to keep this appointment. In some cases, a second test may be done to confirm results. If you have a blood test, the results are often available in a week. Samples of sputum and other body tissues and fluids can take up to 6 weeks for final results.

What do the test results mean

  • Negative results. These mean you likely don’t have the TB bacteria in your body. But in people with some chronic illnesses, the TB tests can be negative even if there is TB in the body.

  • Positive results. These mean that you may have been infected with the TB bacteria. This doesn’t necessarily mean you have active TB disease. You will need more tests, such as chest X-rays, to find out if you have active TB disease. If you don't have active TB, then you are said to have latent TB infection.

© 2000-2021 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
Powered by Krames Patient Education - A Product of StayWell