Pulmonary tuberculosis (TB) is an infectious disease that primarily affects the lungs. It is caused by a bacterium called Mycobacterium tuberculosis. Although tuberculosis is preventable and treatable, untreated disease can become serious and may spread to other people.

Pulmonary TB is particularly important because a person with active disease in the lungs may release TB bacteria into the air when coughing, speaking, singing, or sneezing. Early recognition, appropriate testing, and completion of treatment are essential for protecting both the patient and the community. CDC+1

Important: This article is intended for educational purposes and does not replace examination, testing, diagnosis, or treatment by a qualified healthcare professional.

What Is Pulmonary Tuberculosis?

Pulmonary tuberculosis is tuberculosis involving the lungs. It develops when Mycobacterium tuberculosis bacteria multiply and cause disease in lung tissue.

TB infection and TB disease are not exactly the same thing. A person may have latent (inactive) TB infection, in which TB bacteria are present but controlled by the immune system, without symptoms or the ability to spread TB to others. In active TB disease, the bacteria are multiplying and the person may develop symptoms and, particularly with pulmonary or laryngeal disease, may transmit TB to others. CDC+1

What Causes Pulmonary TB?

The main cause of pulmonary tuberculosis is infection with Mycobacterium tuberculosis.

Unlike many infections that spread primarily through contaminated food, water, or surfaces, TB is mainly transmitted through the air. When a person with infectious pulmonary TB coughs, speaks, sings, or sneezes, tiny particles containing TB bacteria can enter the surrounding air.

A person who inhales these particles may become infected.

However, not everyone who becomes infected develops active TB disease. The immune system can sometimes control the bacteria, resulting in latent TB infection. Active disease can develop later if the bacteria begin multiplying. CDC+1

How Does TB Spread?

Active pulmonary TB can spread from person to person through the air.

Transmission is more likely in situations involving:

• Prolonged close contact with a person who has infectious TB.
• Crowded or poorly ventilated environments.
• Living or working in settings where TB transmission is more common.
• Delayed diagnosis and treatment of infectious TB.

Importantly, latent TB infection does not spread TB bacteria to other people. A person generally becomes a transmission risk when they develop active TB disease capable of releasing bacteria into the air. CDC+1

Pulmonary TB vs. Latent TB Infection

Understanding the difference between latent TB infection and active TB disease is extremely important.

Feature	Latent TB Infection	Active Pulmonary TB
TB bacteria present	Yes	Yes
Bacteria actively multiplying	No or controlled	Yes
Symptoms	Usually absent	Often present
Can spread TB to others?	No	May spread
Chest X-ray	Often normal	May be abnormal
Treatment	Used to prevent active disease	Required to treat active disease

A positive TB blood test or skin test indicates TB infection, but additional medical evaluation is needed to determine whether the person has inactive infection or active TB disease. CDC+1

Risk Factors for Pulmonary Tuberculosis

Anyone can develop TB, but the risk of developing active TB disease is higher in certain circumstances.

Important risk factors include:

1. Close Contact With Someone With TB

People who spend considerable time with someone who has infectious TB may have an increased risk of infection.

2. Weakened Immune System

Conditions or medicines that weaken the immune system can increase the likelihood that latent TB infection will progress to active TB disease.

Examples include HIV infection, certain cancers, and some immune-suppressing medicines. CDC

3. Diabetes

Diabetes is associated with an increased risk of developing TB disease.

4. Crowded Living Conditions

Overcrowding and inadequate ventilation can facilitate airborne transmission.

5. Previous TB Infection

A person who has previously acquired TB infection may develop active disease later, particularly if immune defenses become weaker.

6. Residence or Travel in Areas Where TB Is Common

The likelihood of exposure can be higher in regions where tuberculosis transmission is more widespread.

Symptoms of Pulmonary Tuberculosis

The symptoms of pulmonary TB can develop gradually and may initially appear similar to other respiratory illnesses.

Common symptoms include:

• Persistent cough, particularly a cough lasting three weeks or longer.
• Coughing up sputum or phlegm.
• Coughing up blood in some cases.
• Chest pain.
• Fever.
• Night sweats.
• Unexplained weight loss.
• Loss of appetite.
• Fatigue and weakness.
• Sometimes shortness of breath.

The CDC identifies a prolonged cough, chest pain, and coughing up blood or sputum among important symptoms of pulmonary TB. CDC

Why a Persistent Cough Should Not Be Ignored

A cough lasting several weeks can have many causes, including infections, asthma, allergies, reflux, smoking-related disease, and other lung conditions.

However, when a persistent cough occurs together with fever, night sweats, unexplained weight loss, blood in sputum, or known TB exposure, medical evaluation for tuberculosis may be appropriate.

Can Pulmonary TB Cause Coughing Up Blood?

Yes.

Hemoptysis, meaning coughing up blood, can occur in pulmonary tuberculosis. The amount of blood can vary.

Coughing up blood should not automatically be assumed to be TB because several other lung and airway conditions can cause it. Nevertheless, significant or unexplained blood in the sputum requires medical assessment.

How Is Pulmonary TB Diagnosed?

Diagnosing pulmonary tuberculosis usually involves several pieces of information rather than relying on one test alone.

A healthcare professional may use:

Medical History

The clinician may ask about:

• TB exposure.
• Previous TB infection or treatment.
• Duration and nature of symptoms.
• Travel or residence history.
• Medical conditions affecting immunity.
• Current medications.
• Previous test results.

Physical Examination

A physical examination can provide useful information about a person’s overall condition, although examination alone cannot reliably confirm or exclude TB disease. CDC

TB Blood Test

A TB blood test, also known as an interferon-gamma release assay (IGRA), can help identify TB infection.

Tuberculin Skin Test

The tuberculin skin test (TST or Mantoux test) is another method used to detect TB infection.

A positive TB blood or skin test does not by itself prove that a person has active pulmonary TB. Further evaluation is necessary. CDC+1

Chest X-Ray

A chest X-ray can identify abnormalities that may be consistent with pulmonary TB.

However, an X-ray alone cannot establish the diagnosis in every case.

Sputum Testing

When pulmonary TB is suspected, respiratory samples such as sputum may be examined.

Laboratory testing may include:

• Sputum smear microscopy
• Molecular or nucleic acid amplification tests
• TB culture
• Drug susceptibility testing

Culture remains an important reference laboratory method for confirming TB disease and determining drug susceptibility. CDC

What Is the Role of Molecular TB Testing?

Modern molecular tests can help detect Mycobacterium tuberculosis more rapidly than traditional culture methods.

Some molecular tests can also provide information about resistance to important TB medicines.

Rapid diagnosis is particularly valuable because identifying TB and potential drug resistance early can help clinicians select appropriate treatment and reduce ongoing transmission.

Treatment of Pulmonary Tuberculosis

Pulmonary TB is treatable and curable when appropriately diagnosed and managed.

Treatment requires a combination of anti-tuberculosis medicines rather than relying on a single drug. The exact regimen depends on factors such as:

• Whether the TB is drug-susceptible or drug-resistant.
• Previous TB treatment.
• Laboratory results.
• Other medical conditions.
• Drug interactions.
• Pregnancy and other individual circumstances.

For drug-susceptible TB, treatment may involve several medicines during an initial phase followed by a continuation phase. Depending on the recommended regimen, treatment can last several months. CDC+1

Common Anti TB Medicines

Depending on the treatment regimen, medicines may include:

• Isoniazid
• Rifampin
• Rifapentine
• Pyrazinamide
• Ethambutol
• In selected circumstances, other medicines may be required.

The appropriate combination should be determined by a qualified clinician based on current treatment guidelines and laboratory findings.

Why Must TB Treatment Be Completed?

One of the most important principles of TB treatment is adherence.

TB bacteria can be difficult to eliminate completely. Stopping treatment early, missing doses repeatedly, or taking only some of the prescribed medicines can contribute to treatment failure and drug resistance.

Completing the prescribed regimen helps:

• Cure the infection.
• Reduce the risk of relapse.
• Reduce transmission to others.
• Reduce the risk of developing drug-resistant TB.

Patients should take their medicines exactly as prescribed and discuss side effects or difficulties with their healthcare team rather than stopping treatment independently. CDC+1

What Is Drug Resistant TB?

Drug-resistant tuberculosis occurs when TB bacteria are resistant to one or more medicines used to treat TB.

Drug resistance can make treatment more complicated because different medicines and longer or specialized treatment strategies may be required.

Drug-resistant TB should be managed with appropriate laboratory testing and expert clinical guidance. CDC+1

Possible Complications of Pulmonary TB

Untreated or inadequately treated pulmonary tuberculosis can cause serious complications.

Potential complications include:

• Permanent lung damage
• Significant bleeding from the respiratory tract
• Respiratory problems
• Spread of TB to other organs
• Pleural involvement
• Disseminated or miliary TB
• TB involving the brain or meninges
• Increased risk of death when disease is untreated

TB bacteria can affect organs beyond the lungs, including the kidneys, spine, lymph nodes, and brain. CDC+1

Pulmonary TB and the Immune System

The immune system plays a major role in determining whether TB infection remains controlled or progresses to active disease.

After inhalation, TB bacteria can reach the lungs and interact with immune cells. The immune response may contain the bacteria within structures called granulomas.

If the immune system successfully controls the bacteria, the person may remain in a state of latent TB infection.

If the bacteria overcome immune control and begin multiplying, active TB disease can develop. CDC

How Can Pulmonary TB Be Prevented?

TB prevention involves identifying infection early, treating active disease effectively, and preventing progression from latent infection to active disease.

Important prevention strategies include:

Early Diagnosis

Prompt recognition and evaluation of suspicious symptoms can help reduce delays in treatment.

Appropriate Treatment

Correct treatment of active TB helps cure the patient and reduces the period during which infectious bacteria can be transmitted.

Treatment of Latent TB Infection

People with latent TB infection may be offered preventive treatment to reduce the chance of developing active TB disease. CDC+1

Good Ventilation

Because TB is transmitted through the air, adequate ventilation can help reduce the concentration of infectious particles in indoor environments.

Infection Control Measures

People suspected or known to have infectious pulmonary TB may need specific infection-control precautions according to local public-health guidance.

BCG Vaccination

The BCG vaccine (Bacille Calmette-Guérin) is used in many countries to protect against TB, particularly severe forms of TB in children. Vaccination policies differ between countries, so local public-health recommendations should be followed.

When Should You See a Doctor?

Seek medical evaluation if you have a persistent cough, particularly when it is accompanied by:

• Unexplained weight loss.
• Fever.
• Night sweats.
• Chest pain.
• Coughing up blood.
• Persistent weakness or fatigue.
• Known exposure to someone with TB.

People who have been exposed to TB or have a positive TB blood or skin test should also receive appropriate medical evaluation to determine whether they have latent infection or active disease. CDC+1

Frequently Asked Questions About Pulmonary TB

Is pulmonary tuberculosis contagious?

Active pulmonary TB can be contagious because TB bacteria can be released into the air. However, latent TB infection is not contagious. CDC+1

Can pulmonary TB be cured?

Yes. Tuberculosis is treatable and curable when the appropriate treatment is diagnosed and completed. The treatment plan depends on the type of TB and whether the bacteria are susceptible or resistant to particular medicines. CDC+1

Is latent TB the same as active TB?

No. Latent TB infection means TB bacteria are present but controlled and the person does not have TB disease symptoms or transmit the infection. Active TB disease occurs when the bacteria multiply and cause disease. CDC+1

Can TB affect organs other than the lungs?

Yes. TB can affect the lymph nodes, kidneys, bones, spine, brain, and other organs. TB occurring outside the lungs is called extrapulmonary TB. CDC

How long does pulmonary TB treatment take?

Treatment duration varies according to the regimen and the patient’s circumstances. Drug-susceptible TB may be treated with regimens lasting four, six, or nine months, while drug-resistant TB requires different specialist-guided approaches. CDC+1

Can I stop TB medicines when I feel better?

No. Feeling better does not necessarily mean that all TB bacteria have been eliminated. TB medicines should be taken for the full duration prescribed by the healthcare professional. CDC

Is a positive TB skin test proof of active pulmonary TB?

No. A positive skin test indicates TB infection, but additional evaluation is needed to determine whether the person has latent infection or active TB disease. CDC+1

---

Copyright

© 2026 All Rights Reserved .. It is created for educational purposes. Unauthorized copying or reproduction is strictly prohibited.

---