TB Test Near You: The Two Visits, and What the Reading Means
A TB skin test takes two visits: placement, then a reading 48 to 72 hours later. How to plan it, what a positive or negative result means, and what comes next.
Need a TB test near you for school, work or volunteering? A TB skin test takes two visits: a quick injection in the forearm, then a reading 48 to 72 hours later, when a clinician checks the spot and documents the result. Both visits are short, and you can walk in or book at any of our four metro Denver clinics.
The part people most often get wrong is the timing of the second visit. Here's how to plan it, and what the result actually means.
What is a TB skin test?
The tuberculosis skin test, also called a PPD or TST, checks whether your immune system has ever met the bacteria that cause TB. A tiny amount of test fluid goes just under the skin of your forearm. If your body recognizes it, a firm, raised bump forms at the spot over the next two to three days. The size of that bump is the result.
Schools, healthcare employers, childcare programs, volunteer organizations and some other workplaces ask for one. Bring any form they've given you so it can be filled out correctly.
Visit one: placement
This takes a few minutes. A small needle places the fluid just under the skin on the inside of your forearm, leaving a little raised bubble that flattens within minutes. It's a brief sting.
Afterwards, leave the spot alone. Don't cover it with a bandage, scratch it or rub lotion on it. Showering and washing normally is fine; just pat it dry.
Visit two: the reading, 48 to 72 hours later
The test has to be read by a trained clinician, in person, between 48 and 72 hours after it was placed. You can't read it yourself, and a photo won't do. If you miss that window, the test usually can't be read and has to be placed again from the start.
So before the first visit, look at your calendar. If it's placed on a Monday evening, the reading falls between Wednesday evening and Thursday evening. Because our clinics are open every day, weekends work too. Just check the hours of the clinic you'll return to: Highlands opens at 5 PM on weekdays.
At the reading, the clinician feels for a firm, raised area (not just redness) and measures it in millimeters. You leave with documentation for your school or employer.
What does a TB test result mean?
A negative result means there was no firm bump, or one below the size that counts as positive for you. For most people that's the end of it.
What counts as positive depends on the size of the bump and on your own situation, such as your health, your job and where you've lived or traveled. A positive skin test does not mean you have active, contagious TB. It means your body has been exposed to TB bacteria at some point, or it can reflect a BCG vaccine received as a child in many countries. Many people with a positive test have what's called latent TB: the bacteria are dormant, cause no symptoms and can't be spread.
A positive result usually leads to further evaluation, typically a chest X-ray and a conversation about symptoms, and sometimes a TB blood test. The clinician who reads your test will explain the result and the next steps for your situation.
My form says "two-step". What's that?
Some employers, especially in healthcare, ask for a two-step TB skin test for new staff. That means two complete tests, a week or more apart, so four visits in all. Check your paperwork before you start so you plan the right number of trips.
What does a TB test cost?
The TB skin test is a flat fee: $35 self-pay. It's the same price whether you walk in or book ahead. Current prices for this and our other tests and physicals are on the cost and insurance page.
Call 911 or go to the ER if… you're coughing up blood, have trouble breathing or chest pain, or have swelling of the face, lips or throat, hives spreading over the body, or dizziness or fainting soon after an injection. A cough that's lasted three weeks or more, night sweats, fever or unexplained weight loss aren't a 911 emergency, but they do need a medical visit soon rather than a routine skin test.
Where to find us
Four clinics across metro Denver, all ages welcome, se habla español:
- Hampden (Southeast Denver): 8 AM–11 PM daily
- Littleton: 8 AM–11 PM daily
- Thornton: 8 AM–11 PM daily
- Highlands: Mon–Fri 5–11 PM, Sat–Sun 8 AM–11 PM
Walk in, or book online.
Medically reviewed by Peter Martinuzzi, MD
This article is general health information, not medical advice for your situation. If you are worried, come in or book a telehealth visit — and if it is an emergency, call 911.