Tuberculin Skin Test

Medically reviewed by Drugs.com. Last updated on Apr 6, 2025.

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What is a tuberculin skin test?

A tuberculin skin test is done to see if you are infected with the bacteria that cause tuberculosis (TB). Tuberculin is a liquid that healthcare providers inject into the skin of your arm. Your skin will react to tuberculin if you are infected. TB is a serious infection that usually starts in the lungs. The bacteria are easily spread from one person to another through the air. They can live in your body a long time without making you sick. This is called latent TB. Latent TB can develop into active TB if it is not treated.

Why do I need a tuberculin skin test?

The most common reason for a tuberculin skin test is for a job, such as a healthcare worker. You may need this test if you have been exposed to someone with TB or traveled to an area where TB is more common.

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What do I need to do after the test?

• Return in 2 to 3 days. Your skin must be checked 2 to 3 days after the test. You will need another TB skin test if you do not come back within 3 days.
• Watch for signs of allergic reaction. Some people have an allergic reaction to tuberculin. Seek care immediately if you have any symptoms of allergic reaction, such as hives or swelling.

What do the test results mean?

Your test is negative if there is no change to your skin. Your test is positive if the area around the skin test is raised or hard. Talk to your healthcare provider about your test results. The TB skin test can only show that you were infected with the germ that causes tuberculosis. You will need more tests to learn if you have latent or active TB. The most common tests are chest x-rays and sputum samples.

When should I call my doctor?

• You have questions or concerns about the test or about TB.

Care Agreement

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