Diagnosing and Treating Tuberculosis | American Lung Association

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Diagnosing and Treating Tuberculosis

Top 5 Questions for Your Doctor

See 5 important questions to ask your healthcare provider about TB.

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If it is not treated, TB can be fatal. But TB can almost always be treated and cured if you take medicine as directed by your healthcare provider. Once you begin treatment, within weeks you will no longer be contagious. That means you can't spread the disease to others. If you take your medicine just as your healthcare provider tells you, you should be cured (although there are occasional relapses, indicating some of the germs may survive.)

How Is TB Diagnosed?

TB can be detected through a skin test or a TB blood test.

The skin test is done by injecting a small amount of fluid called tuberculin into the skin in the arm. You will be told to return within 48 to 72 hours to have a healthcare worker check the arm to see if a bump or an induration (thickening)  of the skin has developed. These may be difficult to feel and an experienced healthcare worker should examine the reaction. The healthcare worker will measure the bump or induration and tell you if your reaction to the test is positive or negative. If it's positive, it usually means you have been infected with the TB germ.

The TB blood test measures how your immune system reacts to the germs that cause TB. If you have a positive test for TB infection, it only means that you have been infected with TB germs. It does not tell whether you have developed clinically active TB disease. You will be given other tests, such as a chest X-ray and a check of your sputum (coughed up mucus), to see whether you have clinically activeTB disease.

How Is TB Treated?

Treatment for TB depends on whether a person has clinically active TB disease or only TB infection.

If you have become infected with TB, but do not have clinically active TB disease (this is called latent TB), you should get preventive therapy. This treatment kills germs that are not doing any damage right now, but could so do in the future. The most common preventive therapy is a daily dose of isoniazid (INH) taken as a single daily pill for 6 to 9 months.

If you have active TB disease you will probably be treated with a combination of several drugs for 6 to 12 months. You may only have to stay a short time in the hospital, if at all, and can then continue taking medication at home. After a few weeks you can probably even return to normal activities and not have to worry about infecting others.

The most common treatment for active TB is INH plus three other drugs—rifampin, pyrazinamide and ethambutol. You will probably begin to feel better only a few weeks after starting to take the drugs.

It is very important that you continue to take the medicine correctly (regularly and under medical supervision) for the full length of treatment. If you are being treated in a public clinic you may be asked to take your medicines in the presence of a healthcare worker who will ensure that you have done so. This is called Directly Observed Therapy (DOT).

Drug-Resistant TB

If you take the medicine(s) incorrectly or stop taking the medicine(s) altogether, you may become sick again and will be able to infect others with TB. The TB may be harder to treat a second time if it has become drug resistant. This means that some drugs initially used to treat TB will no longer be able to fight the TB germs in your body. TB that is resistant to more than one drug, called multidrug-resistant TB (MDR TB) is very dangerous to you and to others to whom you can spread the infection.

Take Action

Help fight for better ways to diagnose, treat and prevent TB. Contact your representatives in Washington today to urge them to fully fund critical TB programs.


    Approved by Scientific and Medical Editorial Review Panel. Last reviewed October 11, 2016.

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