Hesperian Health Guides

How to Know if a Person Has TB

If someone with signs of TB in the lungs has negative sputum tests, she should see a health worker trained in treating problems of the lung. She may have pneumonia, asthma, or cancer of the lungs.

The most common sign of TB is a cough that lasts for more than 3 weeks, especially if there is blood in the sputum (mucus that comes up from the lungs). Other signs include loss of appetite and weight, fever, feeling tired and night sweats.

But the only way to know for sure that a person has TB is to have the sputum tested. To get a sample of sputum—and not just saliva (spit)—a person must cough hard to bring up material from deep in her lungs. The sputum is then examined in a laboratory to see if it contains TB germs (is positive).

A person should take 3 sputum tests. If at least 2 of her sputum tests are positive, the woman should begin treatment. If only one test is positive, she should have her sputum tested again and, if it is positive, begin treatment. If the third test is negative, she should get a chest x-ray, if possible, to be certain that she does not need treatment. She should also be tested for HIV since negative sputum tests are more common in people with HIV.

IMPORTANT! Because it is so common for people with HIV to also be infected with TB, all HIV-infected people should be tested for TB. If the TB test is positive, the person should begin treatment right away. And in countries where HIV is common, all people with TB should consider getting an HIV test.

This page was updated:01 Feb 2021