Tuberculosis (TB)
An airborne infection caused by Mycobacterium tuberculosis that may remain inactive or progress to contagious disease, most often affecting the lungs.
What causes Tuberculosis (TB)?
TB is caused by Mycobacterium tuberculosis. It spreads through the air when a person with infectious pulmonary or laryngeal TB coughs, speaks, sings, or breathes in a shared space.
Symptoms and what to notice
Active pulmonary TB can cause cough lasting three weeks or longer, chest pain, coughing blood or sputum, fever, night sweats, weight loss, poor appetite, fatigue, or chills. Inactive TB causes no symptoms and is not contagious.
How long can it last?
Inactive infection can persist for years or life. Active disease requires months of combination antibiotics; exact duration depends on site, susceptibility, regimen, response, and adherence.
How serious is Tuberculosis (TB)?
Untreated TB can destroy lungs, spread to the brain, spine, kidneys, bones, or bloodstream, and cause death. Drug-resistant TB is harder and longer to treat.
Treatment and management
Inactive TB is treated with preventive regimens, often rifamycin-based. Active disease requires multiple antibiotics such as isoniazid, rifampin, pyrazinamide, ethambutol, or newer regimen components under public-health supervision. Never treat presumed active TB with one drug alone.
Vaccine: who and when?
BCG is a TB vaccine used in many countries to protect young children from severe TB meningitis and disseminated disease. It is not generally used in the United States because pulmonary protection varies, U.S. infection risk is low, and BCG complicates skin-test interpretation. Rare U.S. use requires TB-expert consultation.
Cost note: No routine vaccine price applies. Evaluation, testing, and treatment costs vary by provider, insurance, public-health program, and clinical need.
Trusted source
Patient cost varies by insurance, provider, location, and eligibility. Coverage and public-health access differ, so listed prices are examples rather than guaranteed patient prices. This page is for general education and does not replace individualized medical advice, diagnosis, vaccination assessment, or treatment.
Tuberculosis (TB): Symptoms, Causes, Treatment, Prevention, and Vaccine Information
TB exists as inactive infection and active disease. People with inactive TB feel well and cannot spread bacteria, but treatment prevents future disease. People with pulmonary or laryngeal TB may transmit infection through shared air. Diagnosis, susceptibility testing, combination therapy, adherence support, and contact investigation are core public-health measures.
Important: This page is for general education. It does not replace diagnosis, treatment, vaccination advice, or emergency care from a qualified healthcare professional.
Quick Facts
| Topic | Current information |
|---|---|
| Cause | TB is caused by Mycobacterium tuberculosis. It spreads through the air when a person with infectious pulmonary or laryngeal TB coughs, speaks, sings, or breathes in a shared space. |
| Main symptoms | Active pulmonary TB can cause cough lasting three weeks or longer, chest pain, coughing blood or sputum, fever, night sweats, weight loss, poor appetite, fatigue, or chills. Inactive TB causes no symptoms and is not contagious. |
| Typical course | Inactive infection can persist for years or life. Active disease requires months of combination antibiotics; exact duration depends on site, susceptibility, regimen, response, and adherence. |
| Treatment | Inactive TB is treated with preventive regimens, often rifamycin-based. Active disease requires multiple antibiotics such as isoniazid, rifampin, pyrazinamide, ethambutol, or newer regimen components under public-health supervision. Never treat presumed active TB with one drug alone. |
| Vaccine status | BCG is a TB vaccine used in many countries to protect young children from severe TB meningitis and disseminated disease. It is not generally used in the United States because pulmonary protection varies, U.S. infection risk is low, and BCG complicates skin-test interpretation. Rare U.S. use requires TB-expert consultation. |
History and Public-Health Importance
TB was once the leading U.S. infectious killer. Sanitation, housing improvements, antibiotics, and public-health programs drove rates down, but global transmission, HIV, homelessness, incarceration, migration, and drug resistance sustain risk. Shorter preventive and disease regimens continue to improve completion.
What Causes Tuberculosis (TB)?
TB is caused by Mycobacterium tuberculosis. It spreads through the air when a person with infectious pulmonary or laryngeal TB coughs, speaks, sings, or breathes in a shared space.
TB is airborne, not spread by handshakes, toilet seats, dishes, or casual surface contact. Risk rises with prolonged indoor exposure, poor ventilation, and untreated infectious disease. After effective therapy, contagiousness usually falls, but isolation ends only when clinicians and public health determine it is safe.
Symptoms and Typical Course
Active pulmonary TB can cause cough lasting three weeks or longer, chest pain, coughing blood or sputum, fever, night sweats, weight loss, poor appetite, fatigue, or chills. Inactive TB causes no symptoms and is not contagious.
Only a minority of infected people develop active disease, usually within the first two years or later when immunity weakens. Pulmonary symptoms can progress slowly and be mistaken for another illness. Extrapulmonary TB affects lymph nodes, pleura, bones, kidneys, abdomen, brain, or other sites.
Complications and Who Is at Higher Risk
Untreated TB can destroy lungs, spread to the brain, spine, kidneys, bones, or bloodstream, and cause death. Drug-resistant TB is harder and longer to treat.
Miliary spread and TB meningitis are life-threatening. Pulmonary disease can cause cavities, bleeding, chronic breathing impairment, or bronchiectasis. Spinal TB may compress the cord. Incomplete or incorrect therapy promotes resistance and relapse.
How It Is Diagnosed
An interferon-gamma release blood test or tuberculin skin test identifies infection but cannot by itself distinguish active disease. Evaluation adds symptoms, chest imaging, and sputum molecular testing, smear, culture, and drug-susceptibility testing. BCG does not cause a false-positive blood test, so IGRA is preferred for vaccinated people.
Treatment and Recovery
Inactive TB is treated with preventive regimens, often rifamycin-based. Active disease requires multiple antibiotics such as isoniazid, rifampin, pyrazinamide, ethambutol, or newer regimen components under public-health supervision. Never treat presumed active TB with one drug alone.
Regimens must match susceptibility and patient factors. Many drug-susceptible pulmonary cases use an initial four-drug phase followed by continuation therapy, while selected patients qualify for shorter regimens. Latent infection often uses three- or four-month rifamycin-based options. Public-health case management supports adherence, monitors toxicity, and evaluates contacts.
Vaccine Information
BCG is a TB vaccine used in many countries to protect young children from severe TB meningitis and disseminated disease. It is not generally used in the United States because pulmonary protection varies, U.S. infection risk is low, and BCG complicates skin-test interpretation. Rare U.S. use requires TB-expert consultation.
BCG is a live attenuated Mycobacterium bovis vaccine. It protects children against severe disseminated and meningeal TB better than it protects adults against pulmonary disease. In the United States it is considered only for exceptional continuously exposed children or selected healthcare workers after expert consultation. It is contraindicated in pregnancy and significant immunosuppression.
Prevention
Diagnose and treat active disease promptly, improve ventilation, use respiratory protection in healthcare, screen high-risk populations, treat inactive infection, investigate contacts, and follow isolation guidance. BCG is not a substitute for these measures in the United States.
When to Seek Medical Care
Seek evaluation for cough lasting three weeks, coughing blood, night sweats, unexplained weight loss, persistent fever, or known exposure. Emergency care is needed for severe breathing difficulty, major bleeding, confusion, or neurologic symptoms.
Frequently Asked Questions
Is inactive TB contagious?
No. People with latent infection have no symptoms and cannot spread bacteria, but treatment lowers future disease risk.
Does BCG make TB blood tests positive?
No. It can affect the skin test, but not an interferon-gamma release blood test.
Why are several antibiotics required?
Combination therapy kills bacteria in different states and prevents drug resistance.
Is BCG routinely given in the United States?
No. It is reserved for rare, specialized circumstances after expert consultation.
Key Takeaway
TB is airborne, treatable, and preventable through testing, combination therapy, contact work, and treatment of inactive infection. BCG has only a limited U.S. role.
Medical, treatment, and vaccine information was reviewed against official U.S. public-health guidance available through September 2026.