Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Font Size

Measurement of 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 an active infection that can be spread to others.

ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerR. Steven Tharratt, MD, MPVM, FACP, FCCP - Pulmonology, Critical Care Medicine, Medical Toxicology

Current as ofNovember 14, 2014

WebMD Medical Reference from Healthwise

Last Updated: November 14, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

Today on WebMD

Pictures and symptoms of the red, scaly rash.
woman with dyed dark hair
What it says about your health.
woman with cleaning products
Top causes of the itch that rashes.
atopic dermatitus
Identify and treat common skin problems.
itchy skin
shingles rash on skin
woman with skin tag
Woman washing face
woman washing her hair in sink
close up of womans bare neck
woman with face cream