Alert

Updates

Visiting hours have changed as a result of COVID-19. Learn more.

Measurement of a Tuberculin Skin Test Reaction

Measuring a tuberculin skin test reaction

Two to three days after getting a tuberculin skin test, the size of any bump at the site is measured. Your risk of having TB is used along with the size of the bump to determine whether the test is:

  • Positive, meaning you have been infected with TB bacteria.
  • Negative, meaning you have not been infected with TB bacteria or your body cannot respond to the protein injected because of a weakened immune system.

The test cannot tell if you have a latent (inactive) infection or active TB that can be spread to others.

Current as of: July 1, 2021

Author: Healthwise Staff
Medical Review:
E. Gregory Thompson MD - Internal Medicine
Adam Husney MD - Family Medicine
R. Steven Tharratt MD, MPVM, FACP, FCCP - Pulmonology, Critical Care Medicine, Medical Toxicology
W. David Colby IV MSc, MD, FRCPC - Infectious Disease

Symptom Checker

Feeling under the weather?

Use our interactive symptom checker to evaluate your symptoms and determine appropriate action or treatment.

Interactive Tools

Get started learning more about your health!

Our Interactive Tools can help you make smart decisions for a healthier life. You'll find personal calculators and tools for health and fitness, lifestyle checkups, and pregnancy.

Related Locations