Tuberculosis (TB): Symptoms, Transmission, Testing, Treatment and Prevention

Tuberculosis, commonly called TB, is a serious infectious disease caused mainly by the bacterium Mycobacterium tuberculosis.

TB most commonly affects the lungs, but it can also affect other parts of the body, including the lymph nodes, kidneys, spine and brain.

Tuberculosis remains a major global health problem, but there is an important message to remember:

TB is preventable and curable.

According to the World Health Organization (WHO), an estimated 10.7 million people developed tuberculosis worldwide in 2024, including 5.8 million men, 3.7 million women and 1.2 million children.

Approximately 1.23 million people died from TB in 2024, including about 150,000 people living with HIV.

Early diagnosis, appropriate treatment and prevention can save lives and reduce transmission.

What Causes Tuberculosis?

Tuberculosis is caused by bacteria belonging to the Mycobacterium tuberculosis complex.

The bacteria most commonly infect the lungs.

When someone inhales infectious TB bacteria, the germs may reach the lungs.

From there, they may remain controlled by the immune system or, in some circumstances, multiply and cause active TB disease.

TB bacteria can also spread within the body and affect organs outside the lungs.

TB Infection and TB Disease Are Not the Same Thing

Understanding this distinction is extremely important.

Someone can have TB bacteria in their body without having active tuberculosis disease.

This is often called TB infection, latent TB infection or inactive TB.

Another person may have active TB disease.

The two conditions are different.

What Is Inactive or Latent TB Infection?

A person with inactive TB infection has TB bacteria in the body, but the bacteria are controlled and are not causing active disease.

People with inactive TB generally:

• do not feel ill because of TB,
• have no symptoms of active TB disease,
• and cannot spread TB bacteria to other people.

However, inactive TB can later develop into active TB disease.

WHO estimates that approximately 5–10% of people infected with TB bacteria will eventually develop TB disease, although the risk is substantially higher in certain groups.

Preventive treatment can reduce the risk of inactive TB progressing to active disease.

What Is Active TB Disease?

Active TB disease occurs when TB bacteria multiply and cause illness.

A person may develop symptoms and require treatment with several antibiotics.

When active TB affects the lungs or throat, the person may be able to transmit TB bacteria to others through the air.

Active TB affecting only another part of the body is generally much less likely to be infectious through normal respiratory transmission.

Without appropriate treatment, active TB can cause serious illness and can be fatal.

How Does Tuberculosis Spread?

Tuberculosis spreads through the air.

A person with infectious TB disease involving the lungs or throat can release TB bacteria into the air when they:

• cough,
• speak,
• sing,
• sneeze,
• or otherwise expel infectious respiratory particles.

Another person nearby may inhale these airborne bacteria and become infected.

The risk is generally greater when people spend prolonged or repeated periods together in enclosed or poorly ventilated spaces.

TB Is Not Usually Spread Through Surfaces

Tuberculosis should not be confused with infections that spread primarily through contaminated objects.

TB is not normally transmitted by touching surfaces or everyday objects.

It is also not generally spread by:

• shaking someone's hand,
• sharing plates or cutlery,
• touching toilet seats,
• sharing food,
• or casual physical contact.

The main concern is breathing air containing infectious TB bacteria.

Does Sharing Needles Spread TB?

Sharing needles is not the usual mechanism by which tuberculosis itself spreads.

TB spreads primarily through the air.

However, substance use can be associated with circumstances that increase someone's vulnerability to TB, and sharing injection equipment can transmit other serious infections such as HIV and viral hepatitis.

Because HIV substantially increases the risk of developing active TB, these health issues can sometimes be connected—but they are not the same transmission route.

Can You Catch TB From Someone With Latent TB?

No.

People with inactive or latent TB infection cannot spread TB bacteria to other people.

Transmission occurs primarily from people who have infectious active TB disease involving the lungs or throat.

This distinction helps prevent unnecessary fear and stigma towards people who have tested positive for TB infection but do not have active disease.

Who Is More Likely to Be Exposed to TB?

Anyone can become infected with TB, but exposure risk is not equal everywhere.

Risk can be higher among people who:

• live with or spend considerable time around someone with infectious TB,
• live or work in settings where TB transmission is more common,
• spend prolonged periods in crowded or poorly ventilated environments where infectious TB is present,
• live in or frequently travel to countries where TB is more common,
• work in healthcare or other settings where TB exposure can occur,
• or live in congregate settings where transmission risk is increased.

Exposure does not automatically mean that someone will develop active TB disease.

Who Is More Likely to Develop Active TB After Infection?

Some people are more likely than others to progress from TB infection to active TB disease.

Important risk factors include:

• HIV infection,
• diabetes,
• undernutrition,
• tobacco use,
• harmful alcohol use,
• certain cancers,
• medicines that suppress the immune system,
• and other conditions that weaken immune defences.

Babies and young children who become infected also have an increased risk of developing TB disease.

TB and HIV

TB and HIV have an especially important relationship.

HIV weakens the immune system, making it more difficult for the body to keep TB bacteria under control.

As a result, people living with HIV who become infected with TB have a substantially increased risk of developing active TB disease.

WHO reports that TB remained the leading killer of people with HIV in 2024.

Testing, prevention and treatment for both conditions are therefore important.

TB and Diabetes

Diabetes is another important risk factor for developing active TB.

People with diabetes who have been exposed to TB or who live in areas where TB is common may need assessment based on local medical guidance and individual risk.

Good management of diabetes remains important for overall health.

TB and Undernutrition

Undernutrition can weaken the body's ability to fight infection and is associated with an increased risk of TB disease.

People undergoing TB treatment may also experience weight loss and poor appetite.

Nutritional assessment and support can therefore form part of comprehensive TB care where needed.

However, no particular food or supplement can cure tuberculosis.

Antibiotic treatment is essential for active TB disease.

Smoking and Tuberculosis

Tobacco use increases the risk of TB disease and can damage the lungs.

Avoiding or stopping tobacco use therefore supports respiratory health and reduces several major health risks.

Stopping smoking should complement—not replace—appropriate TB testing and treatment.

Alcohol and TB

Harmful alcohol use is associated with increased risk of TB disease.

Heavy alcohol use can also affect nutrition, immune function and a person's ability to complete a long course of treatment.

Reducing harmful alcohol consumption is therefore relevant to TB prevention and overall health.

What Are the Symptoms of Pulmonary TB?

TB symptoms depend on which part of the body is affected.

When TB affects the lungs, possible symptoms include:

• a persistent or prolonged cough,
• coughing up sputum or phlegm,
• coughing up blood,
• chest pain,
• fever,
• night sweats,
• unexplained weight loss,
• loss of appetite,
• weakness,
• and fatigue.

Symptoms can initially be mild.

This is one reason people may have TB for weeks or months before seeking medical attention.

How Long Can a TB Cough Last?

A persistent cough is one of the most recognizable symptoms of pulmonary TB.

Some clinical guidance describes a cough lasting three weeks or longer as a warning sign.

However, people should not wait for an exact number of weeks if they have other concerning symptoms, known TB exposure or significant risk factors.

A prolonged or unexplained cough deserves appropriate medical assessment.

Is Back Pain a Typical TB Symptom?

The old article listed back pain as a general symptom of tuberculosis.

That needs clarification.

Back pain is not one of the main symptoms of ordinary pulmonary TB.

However, tuberculosis can sometimes affect the spine.

Spinal TB can cause back pain and other symptoms related to the affected bones and nerves.

Similarly, TB affecting the brain, kidneys, lymph nodes or other organs can cause symptoms specific to those areas.

What Is Extrapulmonary TB?

Tuberculosis occurring outside the lungs is called extrapulmonary TB.

It can affect areas such as:

• lymph nodes,
• kidneys,
• bones and joints,
• spine,
• brain and surrounding membranes,
• abdomen,
• and other organs.

Symptoms depend on the affected site.

For example:

TB of the lymph nodes may cause persistent swelling.

TB of the spine may cause back pain.

TB involving the brain or its coverings can cause severe neurological illness.

Kidney TB may cause urinary symptoms or blood in the urine.

Extrapulmonary TB requires proper medical diagnosis and treatment.

Can Someone Have Active TB Without Obvious Symptoms?

Yes.

Although active TB commonly causes symptoms, WHO notes that some people with TB disease may have few or no obvious symptoms.

This reinforces the importance of screening and testing among people at increased risk or those who have had significant exposure.

How Is Tuberculosis Diagnosed?

Symptoms alone cannot confirm TB.

Healthcare professionals may use several approaches depending on whether they are investigating TB infection or active TB disease.

Tests can include:

• rapid molecular tests,
• examination of sputum,
• chest imaging,
• TB blood tests,
• TB skin tests,
• and tests on samples from affected tissues or body fluids.

WHO recommends rapid diagnostic tests as the initial tests for people with signs and symptoms of TB where appropriate.

What Is a Sputum Test?

Sputum is mucus or phlegm produced from deep within the lungs.

Someone suspected of having pulmonary TB may be asked to provide a sputum sample.

Laboratory testing can look for evidence of Mycobacterium tuberculosis and may help determine whether the bacteria are resistant to important TB medicines.

Rapid molecular testing has improved the speed with which TB and some forms of drug resistance can be detected.

What Are TB Blood and Skin Tests?

Tests such as a tuberculin skin test (TST) or an interferon-gamma release assay (IGRA) can help determine whether someone has been infected with TB bacteria.

A positive infection test does not by itself prove that someone has active TB disease.

Further assessment may be necessary to distinguish inactive infection from active disease.

How Is Tuberculosis Treated?

Tuberculosis is treated with antibiotics.

For drug-susceptible TB, treatment commonly involves combinations of medicines such as:

• rifampicin,
• isoniazid,
• pyrazinamide,
• and ethambutol.

Treatment regimens depend on the type of TB, drug susceptibility, age, pregnancy, other medical conditions and national or international guidelines.

WHO states that TB medicines generally need to be taken for 4–6 months for common drug-susceptible disease, although particular regimens may differ.

Why Are Several Antibiotics Used?

TB bacteria can develop resistance to antibiotics.

Using an appropriate combination of medicines helps:

• kill TB bacteria effectively,
• reduce treatment failure,
• and reduce the chance that drug-resistant bacteria will emerge.

Patients should follow their prescribed regimen carefully.

Do Not Stop TB Treatment Early

This is one of the most important messages in tuberculosis care.

Someone may begin feeling better after treatment starts, but that does not mean all TB bacteria have been eliminated.

Do not stop TB medication early unless the healthcare team managing your treatment tells you to do so.

Stopping treatment prematurely or taking medicines inconsistently can contribute to:

• treatment failure,
• recurrence,
• continued transmission,
• and drug-resistant TB.

Complete the prescribed treatment.

What Is Drug-Resistant TB?

Drug-resistant tuberculosis occurs when TB bacteria no longer respond adequately to one or more important medicines.

Multidrug-resistant TB (MDR-TB) is particularly concerning because the bacteria are resistant to key first-line medicines.

Drug-resistant TB requires specialized treatment.

WHO describes MDR-TB as an ongoing global public-health and health-security threat.

Preventing resistance is one reason correct diagnosis and completion of treatment are so important.

Can Latent TB Be Treated?

Yes.

People with inactive TB infection who have a significant risk of developing active disease may be offered TB preventive treatment.

The purpose is to kill or suppress TB bacteria before they cause active disease.

Not everyone with a positive TB test receives exactly the same regimen.

The decision depends on factors such as:

• age,
• risk of developing active disease,
• previous exposure,
• medical history,
• possible drug resistance,
• and local clinical guidelines.

What Is the BCG Vaccine?

BCG, or Bacille Calmette-Guérin, is the currently available vaccine against tuberculosis.

It is used in many countries, particularly where TB is more common.

WHO notes that BCG vaccination can protect babies and young children against severe forms of tuberculosis and TB-related death.

However, BCG does not provide complete lifelong protection against pulmonary TB.

This means someone who received BCG can still become infected with TB and may still need testing following significant exposure.

Is BCG Given to Everyone Worldwide?

No.

BCG vaccination policies differ between countries because TB prevalence and individual risk differ.

Some countries routinely vaccinate infants.

Others use targeted vaccination for babies, children or other people considered at increased risk.

Follow the vaccination programme applicable where you live.

How Can TB Transmission Be Reduced?

Important prevention measures include:

• diagnosing infectious TB promptly,
• starting effective treatment,
• completing treatment,
• testing people who have had significant exposure,
• treating inactive TB when appropriate,
• improving ventilation,
• avoiding prolonged exposure to untreated infectious TB in enclosed spaces,
• using appropriate respiratory protection in healthcare and high-risk settings,
• covering coughs appropriately,
• and following public-health advice.

Why Does Ventilation Matter?

TB bacteria can remain suspended in indoor air.

The risk of transmission is therefore greater in enclosed spaces with poor air circulation.

Improving ventilation can dilute infectious particles and reduce the chance that other people will inhale them.

Healthcare and institutional settings may require additional infection-control measures.

What About Face Masks?

Masks and respirators can play a role in TB infection control, but the correct type and use depend on the situation.

A person with infectious pulmonary TB may be advised to wear an appropriate mask to reduce the release of infectious particles.

Healthcare workers and others at occupational risk may require properly fitted respirators according to infection-control procedures.

A simple instruction to “wear a face mask whenever entering a TB institution” is therefore not sufficiently precise.

Follow the infection-control guidance of the relevant healthcare or public-health authority.

Should Someone With TB Be Avoided Completely?

No.

People affected by TB should be treated with dignity and without stigma.

Someone with inactive TB cannot transmit TB.

Someone receiving treatment for active pulmonary TB may become much less infectious after effective treatment, but the exact timing varies.

The healthcare team determines when isolation or other transmission precautions can safely end.

Do not socially exclude someone indefinitely simply because they have had tuberculosis.

When Should You Get Tested for TB?

Consider medical assessment or TB testing if:

• you have had close contact with someone with infectious active TB,
• you have a persistent unexplained cough,
• you are coughing up blood,
• you have unexplained fever, night sweats or weight loss,
• you have HIV or another condition that substantially weakens immunity,
• you have been advised to test because of occupational exposure,
• or you belong to another group considered at increased risk under local health guidance.

Testing recommendations vary between countries.

When Should You Seek Medical Attention?

Seek medical assessment if you develop symptoms that could indicate tuberculosis, particularly a persistent cough combined with:

• fever,
• night sweats,
• unexplained weight loss,
• chest pain,
• fatigue,
• or known exposure to someone with infectious TB.

Coughing up blood requires prompt medical assessment.

Seek urgent medical care if coughing up blood is heavy, you have severe breathing difficulty, severe chest pain, confusion, loss of consciousness or another serious deterioration.

Contact your local emergency medical service if necessary.

TB Is Curable

A diagnosis of tuberculosis can be frightening, but modern treatment can cure TB in most people when appropriate medicines are available and taken correctly.

The priorities are:

Get tested.
Start the correct treatment.
Take every medicine as prescribed.
Complete the full treatment course.
Follow infection-control advice.
Attend follow-up appointments.

Treatment protects both the individual and the wider community.

Seven Important TB Facts

1. TB is caused by bacteria.
The main cause is Mycobacterium tuberculosis.

2. TB spreads through the air.
It is not primarily spread by surfaces, handshakes or shared food.

3. Inactive TB is not contagious.
People with latent TB infection cannot spread TB to others.

4. TB most commonly affects the lungs but can affect other organs.

5. A persistent cough, fever, night sweats and unexplained weight loss are important warning symptoms.

6. TB is preventable and curable.

7. Treatment must be completed.
Stopping antibiotics too early can contribute to treatment failure and drug resistance.

The Bottom Line

Tuberculosis remains one of the world's most serious infectious diseases, but it is both preventable and curable.

TB spreads primarily through the air when someone with infectious disease of the lungs or throat releases TB bacteria.

Not everyone infected with TB becomes ill.

People with inactive TB infection usually have no symptoms and cannot transmit the bacteria, but some will later develop active TB disease.

People with HIV, diabetes, undernutrition, weakened immune systems, tobacco use and harmful alcohol use can face increased risk of developing TB disease.

Persistent cough, chest pain, fever, night sweats, fatigue and unexplained weight loss deserve medical attention, particularly when there has been possible TB exposure.

Testing can distinguish TB infection from active disease and help identify drug resistance.

Effective antibiotics can cure TB, but treatment must be taken correctly and completed.

Early diagnosis and treatment do more than protect one patient—they also help prevent tuberculosis from spreading to other people.

Medical Disclaimer

This article provides general health information for an international audience and is not a substitute for professional medical diagnosis, TB testing or treatment. Tuberculosis testing, vaccination policies and treatment regimens vary according to individual circumstances, drug resistance and national guidelines. If you think you have been exposed to tuberculosis or have symptoms such as a persistent cough, coughing up blood, fever, night sweats or unexplained weight loss, seek assessment from an appropriately qualified healthcare professional.

Sources and Further Reading

World Health Organization — Tuberculosis Fact Sheet

https://www.who.int/news-room/fact-sheets/detail/tuberculosis

World Health Organization — Tuberculosis Health Topic

https://www.who.int/health-topics/tuberculosis

World Health Organization — Tuberculosis Questions and Answers

https://www.who.int/news-room/questions-and-answers/item/tuberculosis

World Health Organization — TB Vaccines

https://www.who.int/teams/immunization-vaccines-and-biologicals/tuberculosis

Centers for Disease Control and Prevention — About Tuberculosis

https://www.cdc.gov/tb/about/index.html

Centers for Disease Control and Prevention — How Tuberculosis Spreads

https://www.cdc.gov/tb/causes/index.html

Centers for Disease Control and Prevention — Signs and Symptoms of Tuberculosis

https://www.cdc.gov/tb/signs-symptoms/index.html

Centers for Disease Control and Prevention — Preventing Tuberculosis

https://www.cdc.gov/tb/prevention/index.html