To diagnosis a tuberculosis (TB) infection, your health care provider will do an exam that includes:
- Listening to you breathe with a stethoscope.
- Checking for swollen lymph nodes.
- Asking you questions about your symptoms.
Your health care provider will order tests if:
- Tuberculosis is suspected.
- You were likely exposed to a person with active tuberculosis (TB) disease.
- You have health risks for active TB disease.
Your provider will determine whether a skin test or blood test is the best option.
A tiny amount of a substance called tuberculin is injected just below the skin on the inside of one forearm. Within 48 to 72 hours, a health care worker will check your arm for swelling at the injection site. The size of the raised skin is used to determine a positive or negative test.
This test is seeing if your immune system reacts, or has made an antibody, to tuberculosis. A positive test indicates you likely have either a latent TB infection or active TB disease. People who had a TB vaccination might get a positive test even if they have no infection.
A negative test means that your body didn't react to the test. It doesn't necessarily mean you don't have an infection.
A sample of blood is sent to a lab. One lab test finds out whether certain immune system cells can "recognize" tuberculosis. A positive test shows that you have either a latent TB infection or active TB disease. Other tests of the blood sample can help determine if you have active disease.
A negative result means you likely do not have a TB infection.
A chest X-ray can show irregular patches in the lungs that are typical of active TB disease.
Your health care provider may take a sample of the mucus that comes up when you cough, also called sputum. If you have active TB disease in your lungs or voice box, lab tests can detect the bacteria.
A relatively quick laboratory test can tell if the sputum likely has the TB bacteria. But it may be showing bacteria with similar features.
Another lab test can confirm the presence of TB bacteria. The results often take several weeks. A lab test also can tell if it's a drug-resistant form of the bacteria. This information helps your health care provider choose the best treatment.
Other lab tests
Other lab tests that may be ordered include:
- Breath test.
- Procedure to remove sputum from your lungs with a special tube.
- Urine test.
- Test of the fluid around the spine and brain, called cerebrospinal fluid.
If you have a latent TB infection, your health care provider may begin drug treatments. This is especially true for people with HIV/AIDS or other factors that increase the risk of active TB disease. Most latent TB infections are treated for three or four months.
Active TB disease may be treated for four, six or nine months. Specialists in TB treatment will determine which drugs are best for you.
You will have regular appointments to see if you're improving and to watch for side effects.
Take all of the drugs
It is important to take every dose as instructed. And you must complete the full course of treatment. This is important for killing the bacteria in your body and preventing new drug-resistant bacteria.
Your public health department may use a program called directly observed therapy (DOT). With directly observed therapy (DOT), a health care worker visits you at home to watch you take your dose of drugs.
Some health care departments have programs that let you take your drugs on your own. The Centers for Disease Control and Prevention has printable forms you can use to keep track of your daily doses.
Most common TB drugs
If you have a latent TB infection, you might need to take only one or two types of drugs. Active TB disease requires taking several drugs. Common medications used to treat tuberculosis include:
- Rifampin (Rimactane).
- Rifabutin (Mycobutin).
- Rifapentine (Priftin).
- Ethambutol (Myambutol).
You may be prescribed other drugs if you have drug-resistant tuberculosis or other complications from your illness.
Medication side effects
Most people can take TB drugs without serious side effects. If you have serious side effects, your care provider may ask you to stop taking a drug. You may have to change the dose of a drug.
Talk to your health care provider if you experience any of the following:
- Upset stomach.
- Loss of appetite.
- Severe diarrhea.
- Light-colored stool.
- Dark urine.
- Yellowish skin or eye color.
- Changes in vision.
- Dizziness or trouble with balance.
- Tingling in hands or feet.
- Easy bruising or bleeding.
- Unexplained weight loss.
- Unexplained tiredness.
- Sadness or depression.
- Joint pain.
It is important for you to list all drugs, dietary supplements or herbal remedies you take. You may need to stop taking some of these during your treatment.
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Coping and support
The long treatment plan for tuberculosis can be challenging. Anger or frustration are normal. Talking to someone, such as a therapist, might help you develop coping strategies.
Preparing for your appointment
You are likely to start with an appointment with your health care provider. You may be referred to a doctor who specializes in treating infectious diseases.
What you can do
When you make the appointment, ask if there's anything you need to do in advance. Make a list of:
- Your symptoms, including any that may seem unrelated to the reason for which you scheduled the appointment, and when they began.
- Key personal information, including recent life changes or international travel.
- All medications, vitamins or supplements you take, including doses.
- Questions to ask your doctor.
For tuberculosis, some basic questions to ask your doctor include:
- What's the most likely cause of my symptoms?
- Do I need tests?
- What treatments are available? Which do you recommend?
- What if the treatment doesn't work?
- How long do I have to stay on the treatment?
- How often do I need to follow up with you?
- I have other health problems. How can I best manage these conditions together?
What to expect from your doctor
Be prepared to answer the following questions during your appointments:
- What symptoms have you had?
- When did your symptoms begin?
- Do you have HIV or AIDS?
- Have you been around anyone with active TB disease?
- Were you born in another country?
- Have you traveled in another country?
- Were you vaccinated against tuberculosis as an infant?
- Have you ever had tuberculosis or a positive TB skin test?
- Have you ever taken medicine for TB? If so, what kind and for how long?
- What kind of work do you do?
- How much alcohol do you drink?
- Do you inject drugs?
- What drugs, dietary supplements or herbal remedies do you take?
Mar 22, 2023
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- AskMayoExpert. Tuberculosis. Mayo Clinic; 2022.
- Extrapulmonary tuberculosis (TB). Merck Manual Professional Version. https://www.merckmanuals.com/professional/infectious-diseases/mycobacteria/extrapulmonary-tuberculosis-tb. Accessed Jan. 4, 2023.
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- Treatment regimens for latent TB infection. Centers for Disease Control and Prevention. https://www.cdc.gov/tb/topic/treatment/ltbi.htm. Accessed Jan. 26, 2023.
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