What Should I Expect After a Positive TB Test?

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  • Written By: Heather Bailey
  • Edited By: Lucy Oppenheimer
  • Last Modified Date: 20 January 2020
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After a positive TB test, a patient can expect a trip to the doctor for an X-ray and a physical to confirm what kind of TB he has. The two main types of TB are active and latent TB. Both types will be treated via antibiotics, though the active type will also include regular checkups and tests.

Tuberculosis, commonly called TB, is a bacterial infection that usually affects the lungs. It can also affect the bones, spine, brain and kidneys. Its most common symptoms are fatigue and endless coughing. Other symptoms include weight loss, fever, chills and trouble breathing.

The test for TB is called the Mantoux tuberculin skin test. It involves injecting a tiny bit of tuberculin purified protein derivative (PPD) into a patient's forearm. About 48 to 72 hours later, a health care professional will be able to read the PPD skin test results. In a positive TB test, there will be a red and swollen circle at the injection site. The size of the circle depends on the health and age of the patient.

With a positive TB test, the next step is a chest X-ray and physical to determine what kind of TB it is. Though there's a small possibility of a false positive TB test, a chest X-ray would be the determining factor. The most likely reason for a false positive is a previous TB vaccine.


The X-ray and exam will determine if the patient has active TB or latent TB. In latent TB, also called TB infection, a person has been exposed to TB and the bacteria are present in his body, but he is neither sick nor contagious. In active TB, also called TB disease, the person has been exposed to the bacteria, they are present in his body and causing symptoms. The person is also contagious. Only about 10 percent of people who have a positive TB test have active TB. Most healthy people can fight off the infection.

If a patient has latent TB, he must still be treated so it does not become active. Treatment is taking a daily antibiotic, known as isoniazid, for six to nine months. It is important the patient takes the pill every day so the disease does not become active and so the bacteria do not become resistant to the antibiotic. During treatment, the patient may need regular checkups to make sure there are no negative effects from the medication.

If a patient has active TB, he must take several antibiotics for six months to fight the disease. Commonly, four medications are prescribed: isoniazid, rifampin, ethambutol and pyrazinamide. During treatment, the patient will probably also have regular exams and X-rays, as well as sputum and blood tests to check on progress of the disease.


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Post 1

In addition to the laboratory test of the sputum, a spinal tap may be performed also to test for infection of the brains membrane. Since this is a very serious condition that can cause brain damage and can be fatal, it is important to start treatment as quickly as possible.

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