How to recognize symptoms that might mean you have tuberculosis

Tuberculosis (TB) causes a persistent cough that lasts three weeks or longer, often with mucus or blood. You may also have chest pain when you breathe or cough, fever that comes and goes, night sweats that soak your clothes, and unexplained weight loss or loss of appetite. These symptoms develop slowly over weeks or months, not suddenly like flu.

Not everyone with TB symptoms has active TB disease. Some people carry the TB bacteria but do not feel sick and cannot spread it to others—this is called latent TB infection. Only a doctor can tell the difference through testing. If you have had any of these symptoms for more than three weeks, you need a medical evaluation.

Key Takeaways

  • A cough lasting longer than three weeks, especially with mucus or blood, is the most common sign of active TB disease.
  • Fever, night sweats, weight loss, and chest pain are other symptoms that develop slowly over weeks or months.
  • A skin test or blood test is the only way to know if you have TB infection; you cannot diagnose it yourself.
  • If you have symptoms or know you were exposed to someone with TB, contact your doctor or local health department for testing.
  • Starting treatment early prevents TB from becoming severe and stops you from spreading it to others.

Who should get tested for TB

You should get tested if you have had symptoms for three weeks or longer, or if you know you were in close contact with someone who has active TB disease. Close contact means spending time in the same room, breathing the same air for several hours over days or weeks.

You should also get tested if you have a weakened immune system from HIV, diabetes, kidney disease, or medications that suppress immunity. People who were born in or recently traveled to countries where TB is common, or who live or work in crowded settings like shelters or prisons, have higher risk and may benefit from testing even without symptoms.

What happens during TB testing

Your doctor or health department will use one of two main tests. The tuberculin skin test (also called the Mantoux test) involves injecting a small amount of TB protein under your skin on the forearm. You return 48 to 72 hours later, and a nurse measures any bump or hardness that formed. A larger reaction suggests TB infection, though the result alone does not tell whether you have latent or active disease.

The TB blood test (called an interferon-gamma release assay, or IGRA) measures how your immune system responds to TB proteins in a sample of your blood. Results come back in one to two days. Blood tests are more accurate than skin tests in some situations, such as if you received a BCG vaccine in another country.

If either test shows TB infection, your doctor will order a chest X-ray to look for signs of active TB disease in your lungs. If the X-ray shows changes, you may also have a sputum test—you cough into a cup so the lab can check the mucus for TB bacteria under a microscope.

The difference between latent and active TB

With latent TB infection, the bacteria are in your body but dormant. You have no symptoms, do not feel sick, and cannot spread TB to others. A skin test or blood test will be positive, but your chest X-ray is normal. Many people with latent TB never develop active disease, but the risk is higher if your immune system weakens later.

With active TB disease, the bacteria are multiplying and damaging your lungs. You have symptoms like cough, fever, and night sweats. Your chest X-ray shows changes, and your sputum test may show TB bacteria. Active TB can spread to others and will get worse without treatment.

What to do if your test is positive

A positive skin test or blood test means you have TB infection, but does not automatically mean you have active disease. Your doctor will review your symptoms, chest X-ray results, and sputum tests to determine which type you have. This step is important because latent and active TB are treated differently.

If you have latent TB, your doctor may recommend preventive treatment with antibiotics to lower your risk of developing active disease later. If you have active TB, you will need a combination of antibiotics taken for several months. Treatment works, but you must take all the medicine as prescribed, even after you start feeling better.

Tell your doctor about any other medicines you take, any allergies, and any liver or kidney problems, because some TB medicines interact with other drugs or can cause side effects.

Where to get tested

You can get tested through your primary care doctor, an urgent care clinic, or your local health department. Many health departments offer free or low-cost TB testing and do not require insurance. Call your local health department to ask about testing locations and hours.

If you do not have a doctor, search online for "TB testing near me" or "health department [your city]" to find clinics in your area. If you are homeless, in a shelter, or in jail, staff can arrange testing for you. If cost is a concern, ask about sliding-scale fees or free services.

What happens after diagnosis

If you are diagnosed with active TB, your health department will likely contact you to make sure you start treatment and take your medicine correctly. This is called case management and is standard practice, not punishment. The goal is to help you recover and prevent TB from spreading.

You will need to see your doctor regularly while taking TB medicine—usually monthly at first. Your doctor will check for side effects, make sure the medicine is working, and order follow-up tests. Most people with active TB stop being contagious after two weeks of correct treatment, though they must continue taking medicine for the full course.

Frequently Asked Questions

Can you have TB without a cough?

TB usually causes a cough, but some people have active TB in other parts of the body—bones, kidneys, or lymph nodes—without lung symptoms. If you have fever, night sweats, and weight loss but no cough, mention this to your doctor. Testing can still find TB infection.

How long does it take to get TB test results?

A skin test requires a return visit 48 to 72 hours after injection. A blood test gives results in one to two days. A chest X-ray is usually done the same day or within a few days. If sputum tests are needed, results take three to eight weeks.

If my test is negative, does that mean I definitely do not have TB?

A negative test is reassuring but not absolute. If you were recently exposed to TB, your immune system may not have mounted a response yet, and the test could be falsely negative. If you have symptoms, your doctor may repeat testing or order a chest X-ray regardless of the test result.

Can TB go away on its own without treatment?

Active TB does not go away without treatment. It will worsen over time, damage your lungs, and spread to others. Latent TB may never become active, but treatment with antibiotics reduces the risk significantly. Either way, treatment is the safest path.

What should I do if I think I was exposed to someone with TB?

Contact your doctor or health department right away and tell them about the exposure. They will recommend testing even if you have no symptoms. Testing is free or low-cost at most health departments. Do not wait for symptoms to develop.