What Does a Positive TB Test Look Like?


m_jpg120056fa (1)Tuberculosis or (TB) as it is often referred to in short is a highly contagious disease caused by TB bacteria present in the air. Although it can affect other parts of the body such as the lymph nodes, it most commonly impacts the lungs. A person can have active Tuberculosis (where the TB symptoms are apparent) or they can have inactive Tuberculosis (where the infection lays dormant in the body and shows no symptoms.)

When Tuberculosis is active it will cause symptoms such as coughing, weakened immune system, malaise, body aches, night sweats, high fever, chills, and sudden weight loss. This disease can also be fatal as it attacks various organs in the body and causes tissue to die.

Worst of all, Tuberculosis is deadly and can prove fatal in it’s active mode!

Getting Tested for Tuberculosis

Mantoux_tuberculin_skin_testOnce you see your family practitioner or go to a clinic to get tested for Tuberculosis a medical professional or a licensed nurse will inject a small dose of antigens (TB proteins also termed as a PPD- Purified Protein Derivatives) into your skin by needle.  The site of injection is always done on the middle of the forearm.

After the Tb proteins are injected the site of the injection will take on the appearance of a small bubble that looks like the picture posted to the left/above.

After this part of the test is complete, you will have to return to where you had the injection performed in 3-days time to get it read to either diagnose you with positive or negative TB..

What Does a Positive Tuberculosis TB Test Look Like?

The erythema does not show a positive PPD test. A negative result will not always look just like the day you received the injection because there may be an induration or another mark still in the spot. Roughly 48 to 72 hours after getting the test, the reaction will be measured in millimeters at the induration. The induration is basically the raised, swollen, hardened area. It is not the redness that is measured, only the swelling. The dimater is measured to see if the person is positive or negative for TB.

As the provider examines your arm, they are able to determine whether or not you have TB or not. They will determine whether or not they need to use a ruler or measuring tape to accurately diagnose you.

In a negative reaction the skin will most likely not be bright red, hard or look affected. It will look similar to the day you received the injection, but there may be a slight redness or indentation.

In a positive reaction the skin will be tough, hard, and take on an inflamed, reddish hue. It will have a large induration. positive Tb test 2

There are 3 main standards of measurement that the Center for Disease Control (CDC) has put into place to gauge whether a person should be diagnosed with a positive Tuberculosis test:

  • 15 MM: If the redness and reaction measure 15 mm or more in anyone with or without underlying health issues they should be diagnosed as TB positive.
  • 10 MM: Children. substance abusers, Immigrants, and those with additional health problems should be diagnosed TB positive if their reaction measures 10 mm.
  • 5 MM: Those who have serious health problems or at are a higher risk for Tuberculosis should and can be diagnosed as positive with a reaction that measures 5 mm.

If you are still wondering “what does a positive TB test look like” please reference the images below:

Negative TB Test


Positive TB Test


What Happens if You Tested Positive for Tuberculosis

If your physician diagnoses you TB positive they will most likely order you to have a chest X-Ray performed. Depending upon how sick you are they may even suggest you be admitted to the hospital to get immediate treatment if you have active TB. If you have dormant TB then your health provider will most likely provide you with antibiotics you can take at home for a duration of time. This preventative measure for those with dormant TB will help aid them to not become active with the disease.

Learn to Recognize the Symptoms of Tuberculosis

Tuberculosis is spread through the air and from person to person. You can only contract the disease from being exposed to someone who has it in its active state. You cannot catch Tuberculosis from someone who has it in its dormant state!

If someone who has the active disease sneezes, coughs, breathes close enough to you and you get in contact with their bodily fluids or airspace- you can catch it.

Tuberculosis can be deadly if not treated with several strong courses of antibiotics. The key to catching it early relies on being aware and educated of the following symptoms associated with TB.

  • Coughing
  • Bloody Phlegm with Cough
  • Chest Pain
  • Night Sweats
  • Shaking Chills
  • High Fever of 101 degrees fahrenheit or more
  • Malaise
  • Weight Loss
  • Fatigue
  • Loss of Appetite

In order to protect yourself from the likes of this heinous disease or if you are suffering from relative TB symptoms, you should immediately seek medical attention and opt for what is known as a TB test (Mantoux tuberculin Test.)

Note: The symptoms of TB (Tuberculosis) are often commonly related to other types of sicknesses, diseases, and health problems. Just because you have these symptoms it does not necessarily mean you have TB, however it is in your best interest that you get tested so that your doctor can rule out TB and help you to also diagnose any other problem that may be causing the symptoms.


  1. i got a tb test 2 day ago and i’ve scratched on two occasions when i took baths. I got one when i was younger and it was negative but this one looks kinda swollen. im waiting three day and im not going to touch it the third day. when i get it checked will it be ok?

    • You can’t know for sure yet what the results are. While it can be nerve wracking to wait, it is all you can do at the moment. Try not to scratch or mess with the spot and go back to the doctor to get your results. Good luck, John!

    • The diagnosis is based on the size of the raised bump, not the inflammation, so you may be worried unnecessarily. You still need to return to the doctor to get checked for sure.

      • I am a caregiver the guy I stay with was diagnosed with active TB yesterday and died the next day(today) he liked a month being 100. Now I’m worried was tested today and waiting to see. What’s the chances I caught it

        • Tuberculosis spreads more easily if you have close, ongoing contact with someone who is infected. For the moment though, there is no way to know if you do or do not have tuberculosis. All you can do at the moment is wait for your test results. It is not easy to wait, but that is the only way to find out for sure. Good luck, Sandy!

    • Try to not touch your test. You will not know the results until you speak with your doctor. Reduce stress on your body at this time and wait for your doctor’s response. Best of luck, Willy!

  2. Just got my first shot – and that nurses uses Isopropyl alcohol instead of Ethyl alcohol to clean up skin before shot – and I’m allergic to that Isopropyl alcohol (like many folks). I see the label on the bottle after she starting clean up my hand before shot so I ask her and she seems not surprised – and she clean up my hand with hydrogen peroxide to get rid of that Isopropyl, when she realizes I may have allergic reaction to that Isopropyl, but I still worry about the results.
    Also I wonder how many folks actually have allergy to that Isopropyl alcohol and didn’t know that and get bad test result?!

    • This will not have an influence on your tb test. You may see additional swelling or discoloration. Do not allow that to concern you. Your doctor will be able to alleviate your fears in the future. Remain positive as you wait for your test results and do not stress. Remain positive as you move forward. Good luck, Atti!

  3. I’m concerned I had my tb test on Wednesday had it read by the nurse at my job she said it looked positive it’s smaller than a dime not swollen she sent the paper to my drs office and tomorrow have to get a X-ray and blood work I’m so afraid is this serious, what happens next ?

    • Do not concern yourself with the result until you see them. Monitor the experiences that you are having and report anything unusual to your doctor. Reduce stress on yourself if you are able. Try to relax and take this time for yourself. Speak with your doctor tomorrow and listen to their instructions and advice. Best of luck, Adalaina!

  4. One thing I have learned about tb skin tests , is that sometimes the skin test is very inaccurate. My daughter and my husband both are allergic to the skin test. It reads that they are positive for tb. They are not. Some people will read false positive. If that happens, you need to schedule a chest x ray to make sure you don’t have it. Chances are you don’t, you just may be allergic to the skin test. Just a piece of useful information I thought I would pass on.

  5. So I have read most of the questions and almost every time you r response is a ‘no answer’ with the exception of “talk to your doctor”. It seems it is NOT worth the time to write you. Of course we need to talk to our doctor, but writing you is a waste of energy if that is all the advice you give out!

    • It would be impossible–and extremely ill-advised–to make a diagnosis based on a comment online. The only way to diagnose someone competently is in person. The articles are here for people to read and gain more information, but the only way to get diagnosed with TB is to go to your doctor and find out. While I understand that this is frustrating, it would be entirely irresponsible to make a medical diagnosis through just a comment.

    • Sometimes these tests can be inconclusive. If you are taking a TB test, then it is important to have certainty about your status. It is more normal than you may think. Do not be concerned, and instead take this time to focus on your future career. It is likely that your career choice has an important reason for having you take two tests. Remain positive, Crystal.

    • Every person’s body reacts differently to TB tests. If it continues to grow, then perhaps call your medical provider if you find that you are concerned. However, it is likely that you are fine unless you have been exposed to it. Your doctor should be calling you shortly to give you your results. Keep an eye on it and if you become concerned, then take note of the changes.

    • It is difficult to make any determinations regarding TB tests based on the reaction. If you find that you are concerned, then speak with your doctor. However, they will give you the information when they receive it, so you should feel confident in their response. Remain positive as you wait for their word.

    • I would just go to your doctor and ask. A positive result should be apparent at three days, and it should be quite inflamed. A negative test could still cause a bit of redness around the injection though, so just go to your doctor and ask.

  6. I got a tb test done weds. and my arm is like bruised from it is that normal…. (i get bruised easily from shots and ivs to…. )

    • There is no way for me to be certain. However, bruising is normal, especially if you easily bruise. Speak with your doctor to determine your status. However, it is not likely that you have TB unless you have traveled to places where it has proliferated.

  7. My xray said that my left lung has hazed,,and remarked as TB,,but i don’t have any symptoms,,i have never had a contact in person who have TB.

    • You should speak with your doctor regarding this test. It would be unwise of me to attempt to diagnose TB without a x-ray to read. It is possible that in your life you have came in contact with someone who has had TB. Call your doctor when you are able to clear up any concerns that you have.

  8. i had a tb test and it itched so i accidently itched it a couple times and now its kind of puffy and red. what should i do?

    • It will be fine if you just itched it. In time, it will return to normal. Try to not itch it again in the future. Remain positive as you move forward.

  9. I had to get a Two step TB test for my job that I’m going to be taking courses for (phlebotomy) and I had to get two tests done. The first test, the area was red and a little swollen but nothing inflated in the middle and no “white” swelling. I went in today, a week later, to get my second test and a few hours went by and now it’s raised, swollen and it’s white. Is this common for a two step TB test? Or do I have TB?

    • It would be unwise for me to answer your question as I do not have the information in front of me. Swollen skin is normal. Call your doctor when you are able to get an answer that you know is correct. They will have your information and can put your mind at ease.

    • The best course of action is to speak directly with the doctor who gave you the skin test. They will be able to answer your questions in full as they have information about your body and the time frame between the tests. Give them a call as they have your information and should be taking care of you and your questions. Call them as soon as you are able.

  10. I’ve taken the ppd test two years ago. Took it yesterday for my medical exam, the area is itchy and red…it started off as a small bump that went away, the area remained the same not red or swollen…hours later it became very red but not inflated at all. Now it’s pink, less overall area but itchy. I don’t have any of the symptoms (Thank God), is this normal?

    • If you had a medical exam, then it would be wise to speak with your medical professional regarding the results of the test. They will have the answers that you seek because they should know your medical history. If you are unable to speak to your doctor, then monitor the area. If it goes away naturally, then it is likely that there is no problem. Keep note of the changes that you are experiencing to best answer any questions.

    • If you are finding your symptoms are not going away with the next week, then you should look into making an appointment with a medical professional. It is always better to be safe than sorry.

    • If there is any concern regarding pregnancy, then take a pregnancy test. Keep any bodily changes in mind for future reference.


Please enter your comment!
Please enter your name here