Good to knowOne result rarely tells the whole story. Your provider looks at your results together with your symptoms, exam, and other tests.
What the test is
The skin test needs a return visit in 48 to 72 hours. Blood tests (IGRA) need one visit and aren't affected by the BCG vaccine.
Why it's done
- Health care, school, or job requirements
- Close contact with someone with TB
- Before starting medicines that weaken the immune system
- Cough, night sweats, weight loss, or fever
Getting ready and what happens
- For the skin test, plan to return in 2 to 3 days.
How the test is done
- Skin test: a small amount of fluid is injected under the skin of the forearm, then the bump is measured.
- Blood test: a regular blood draw.
What the results mean
Positive
A chest X-ray checks for active TB. Most people have latent TB, which is treated to prevent future illness.
Negative
TB infection is unlikely, though very recent exposure may need a repeat test.
When a result needs quick action
Call your provider todayCoughing blood, high fever, or significant weight loss
Questions to ask your provider
- What do my results mean for me?
- Do I need to repeat this test or have other tests?
Risks
A blood draw is very safe. You may have slight pain or a small bruise where the needle went in.
Related conditions
Related medicines
Related tests
Sources
Last updated 2026-11-13.