Tuberculosis (TB): Symptoms, Causes, and Treatment
Tuberculosis, or TB, is an infection caused by the bacterium Mycobacterium tuberculosis. It most often affects the lungs but can affect the lymph glands, bones and spine, kidneys, brain and other organs. It spreads through the air when a person with active lung or throat TB coughs, speaks or sings; it is not caught from touching surfaces or sharing cutlery, and usually needs close, repeated contact. About one in four people worldwide carry TB bacteria, but in most the bacteria are dormant, cause no symptoms and cannot be passed on: this is called latent TB infection. Only around 5 to 10 in 100 people with latent TB ever develop active TB disease, which does cause illness and can spread. Active pulmonary TB typically causes a cough lasting more than 3 weeks, sometimes with blood, along with weight loss, tiredness, a high temperature and drenching night sweats. TB is diagnosed with a chest X-ray, sputum tests and a rapid molecular test, plus a skin or blood test for latent infection. It is curable: standard treatment is 6 months of four antibiotics (isoniazid, rifampicin, pyrazinamide and ethambutol), and latent TB is treated with a shorter course. Drug-resistant TB needs longer, specialist treatment. TB is a notifiable disease in the United States, the United Kingdom and Australia, so close contacts are traced and offered testing.
In plain words
Tuberculosis, or TB, is an infection caused by a germ. It mostly attacks the lungs. It can also affect other parts of the body. TB spreads through the air. A person with active lung TB spreads it when they cough or talk. You do not catch it from touching things or sharing food. You usually need long, close contact to catch it. Many people carry the germ but it stays asleep. This is called latent TB. Latent TB has no signs and does not spread. Only some people with latent TB ever get sick. Active TB causes a cough that lasts more than 3 weeks. It also causes weight loss, fever, night sweats, and feeling very tired. Doctors find TB with a chest X-ray, spit tests, and a skin or blood test. TB can be cured. The main treatment is antibiotics taken for at least 6 months. You must take every dose and finish the whole course. Stopping early can make the germ hard to treat. TB is a disease that must be reported, so close contacts are offered a test.
What is Tuberculosis (TB): Symptoms, Causes, and Treatment?
Tuberculosis, or TB, is an infection caused by the bacterium Mycobacterium tuberculosis. It most often affects the lungs but can affect the lymph glands, bones and spine, kidneys, brain and other organs. It spreads through the air when a person with active lung or throat TB coughs, speaks or sings; it is not caught from touching surfaces or sharing cutlery, and usually needs close, repeated contact. About one in four people worldwide carry TB bacteria, but in most the bacteria are dormant, cause no symptoms and cannot be passed on: this is called latent TB infection. Only around 5 to 10 in 100 people with latent TB ever develop active TB disease, which does cause illness and can spread. Active pulmonary TB typically causes a cough lasting more than 3 weeks, sometimes with blood, along with weight loss, tiredness, a high temperature and drenching night sweats. TB is diagnosed with a chest X-ray, sputum tests and a rapid molecular test, plus a skin or blood test for latent infection. It is curable: standard treatment is 6 months of four antibiotics (isoniazid, rifampicin, pyrazinamide and ethambutol), and latent TB is treated with a shorter course. Drug-resistant TB needs longer, specialist treatment. TB is a notifiable disease in the United States, the United Kingdom and Australia, so close contacts are traced and offered testing.
Symptoms
Early symptoms
- A cough lasting more than 3 weeks: A persistent cough is the classic sign of TB in the lungs. It often brings up phlegm and, as the disease advances, the phlegm may be streaked with blood. (3) (2) (1)
- Weight loss and loss of appetite: Unintended weight loss over weeks, with little interest in food, is common and is one reason TB was once called 'consumption'. (3) (1) (2)
- Fever and drenching night sweats: A raised temperature, often in the afternoon or evening, and sweats heavy enough to soak the bedclothes. (3) (1) (2)
- Tiredness and feeling generally unwell: Persistent tiredness, weakness and a run-down feeling that does not lift. (3) (1)
- Chest pain or breathlessness: Pain on breathing or coughing, and breathlessness, can occur as TB damages lung tissue or causes fluid around the lung. (1) (2)
- Symptoms from TB outside the lungs: TB elsewhere causes symptoms in that area: painless swollen glands (often in the neck), back pain and stiffness (spinal TB), blood in the urine (kidney TB), a swollen joint, or headache and confusion (TB meningitis). Any of these with fever and weight loss should be checked. (3) (2)
Serious or emergency symptoms
- Coughing up blood: Coughing up blood, or phlegm with blood in it, can be a sign of active TB or of another serious lung problem and always needs prompt assessment. A large amount of blood is an emergency. For a small amount, get an urgent same-day appointment or call a medical helpline (NHS 111 in the UK; your doctor or a nurse line in the US and Australia). For a large amount of blood, or if you are struggling to breathe, call the emergency services: 911 in the United States, 999 in the United Kingdom, or 000 in Australia. (3) (2)
- Severe headache, stiff neck, confusion or drowsiness with fever: These can be signs of TB meningitis or TB affecting the brain, which is a medical emergency and is more common in young children and people with a weakened immune system. Call the emergency services now (911 / 999 / 000) or go straight to an emergency department. (2) (1)
- Getting rapidly more unwell, very breathless, or confused during TB: Widespread TB through the bloodstream (miliary TB), severe lung TB, or a serious drug reaction can cause a fast decline. Seek emergency care (911 / 999 / 000). (1) (2)
Causes
Primary causes
- Infection with Mycobacterium tuberculosis: TB is caused by a slow-growing bacterium, Mycobacterium tuberculosis. Its slow growth is why treatment has to last months rather than days. (2) (1) (4)
- Spread through the air: When someone with active TB in the lungs or voice box coughs, speaks, sings or sneezes, tiny droplets carrying the bacteria are released and can stay in the air of a poorly ventilated room for hours. Others become infected by breathing them in. TB is not spread by touching surfaces, shaking hands, sharing food or cutlery, or kissing, and usually needs prolonged close contact such as living in the same household. (2) (3) (1)
Contributing factors
- Latent TB infection: In most people who breathe in TB, the immune system walls the bacteria off and they lie dormant. This is latent TB infection: there are no symptoms, the person feels well, and they cannot pass TB to anyone. A skin or blood test is positive, but a chest X-ray is normal. Latent TB is not the disease, but it can 'wake up' later. (2) (3) (1)
- Reactivation of latent TB: About 5 to 10 in 100 people with latent TB develop active disease at some point, usually within the first 2 years but sometimes decades later. The risk is much higher, and can happen soon after infection, if the immune system is weakened. (1) (2)
- Conditions and treatments that weaken immunity: HIV (which makes active TB about 12 times more likely), diabetes, malnutrition, the medicines used after an organ transplant, some cancer treatments, long-term steroids and certain arthritis biologic drugs all raise the risk that latent TB becomes active. Silicosis, a lung disease from dust, also increases the risk. (1) (2) (4)
Risk factors
Close contact with someone who has active TB
Living with, or spending long periods near, a person with untreated active lung TB is the main way people become infected. This is why close contacts are traced and tested. (3) (2)
Coming from, or spending time in, a country where TB is common
In the United States, the United Kingdom and Australia most TB occurs in people who were born in, or have lived in, parts of the world where TB is widespread, such as much of sub-Saharan Africa and South and South-East Asia. (2) (3) (5)
A weakened immune system
HIV, diabetes, undernutrition, organ transplant, chemotherapy, long-term steroids and some biologic medicines all increase the risk of TB disease. (1) (2)
Crowded or institutional living, and homelessness
Shelters, prisons, some workplaces and crowded housing make airborne spread more likely. (2) (3)
Smoking, harmful alcohol use, and young age
Smoking and heavy alcohol use raise the risk of TB disease. Babies and young children who are infected are more likely than adults to become ill and to develop severe forms such as TB meningitis. (1) (2)
Diagnosis
How TB is diagnosed depends on whether active disease or latent infection is suspected. For someone with symptoms, the main tests are a chest X-ray, which usually shows changes in the upper parts of the lungs, and samples of phlegm (sputum). A rapid molecular test on the sputum, such as the Xpert MTB/RIF test, is now the recommended first test in the United States, the United Kingdom, Australia and by the World Health Organization: it detects TB and checks for resistance to the key drug rifampicin within a day. Sputum is also grown in the laboratory (culture), which takes weeks but confirms the diagnosis and gives a full drug-sensitivity result. TB outside the lungs is diagnosed with samples or biopsies from the affected area and scans. For latent TB, where there are no symptoms, a TB blood test (interferon-gamma release assay, IGRA) or a tuberculin skin test (the Mantoux test, read after 2 to 3 days) is used, together with a normal chest X-ray to rule out active disease. Everyone diagnosed with TB is also offered an HIV test, because the two conditions are closely linked.
Chest X-ray
Shows lung changes typical of active TB. A normal chest X-ray with a positive skin or blood test points to latent infection rather than disease. (3) (2)
Sputum tests: rapid molecular test and culture
The rapid molecular test detects TB and rifampicin resistance within a day. Culture takes weeks but confirms the diagnosis and gives full drug-sensitivity results. (1) (2) (3)
TB blood test (IGRA) or tuberculin skin test (Mantoux)
Detects TB infection, used mainly to diagnose latent TB or to screen contacts and people about to start immune-weakening treatment. It cannot tell latent infection from active disease on its own. (2) (3)
HIV test
Offered to everyone diagnosed with TB, because HIV greatly increases TB risk and changes treatment. (1) (2)
Treatment
Medication options
Standard treatment for active drug-sensitive TB
Active TB that is not drug-resistant is cured with a 6-month course of antibiotics: 2 months of four drugs together, isoniazid, rifampicin, pyrazinamide and ethambutol, followed by 4 months of isoniazid and rifampicin. Several drugs are used together because the bacteria develop resistance quickly if only one is used. Most people are no longer infectious after about 2 weeks of effective treatment and feel much better within a few weeks, but the full 6 months is needed to kill every last bacterium and prevent relapse. Newer 4-month regimens that include rifapentine and moxifloxacin are now an option in some countries. (3) (2) (1) (4)
Treatment for latent TB infection
Latent TB is treated to stop it ever becoming active disease, which is especially important for recent contacts, children, and people who are about to start or are on immune-weakening treatment. Modern short courses are 3 months of isoniazid plus rifapentine taken weekly, 3 months of isoniazid plus rifampicin daily, 4 months of rifampicin daily, or 6 to 9 months of isoniazid. (2) (3) (1)
Treatment for drug-resistant TB
TB that is resistant to rifampicin, or to both rifampicin and isoniazid (multidrug-resistant TB), needs a different combination of drugs. A 6-month all-oral regimen called BPaLM, containing bedaquiline, pretomanid, linezolid and moxifloxacin, is now recommended by the World Health Organization for most people with multidrug-resistant TB and is far shorter than the older 18 to 24 month regimens. (1) (2)
Lifestyle and self-care
- Prevention: treat latent TB and control the source: The spread of TB is reduced by finding and treating active cases quickly, treating latent TB in people at risk, and by good ventilation and, in healthcare, respiratory protection. If you have infectious TB you may be asked to stay away from work, school and crowded places, and to cover your mouth when coughing, for the first couple of weeks of treatment. (2) (1) (3)
- The BCG vaccine: The BCG vaccine gives useful protection against severe TB in babies and young children, especially TB meningitis, but is less reliable against lung TB in adults. It is given routinely to infants in many high-TB countries, and in the United Kingdom and Australia is offered to babies and children at higher risk. It is not used routinely in the general population of the United States. (1) (3) (2)
- Living with TB: contact tracing and notification: Active TB is a notifiable disease in the United States, the United Kingdom and Australia. The public-health team will contact people you have spent a lot of time with to offer them testing. This is routine, is kept confidential, and protects your family and friends. (3) (2) (5)
- Support your recovery: Eat well to regain lost weight, stop smoking, limit alcohol (which is hard on the liver while on TB drugs), and keep all follow-up appointments and blood tests. Tell your TB nurse if side effects make it hard to take the medicine, so it can be managed rather than missed. (1) (3)
- Tell health workers if you have been exposed: If you have spent time with someone who has TB, or have symptoms and have lived in a high-TB country, tell your doctor so testing can be arranged. Latent TB found and treated now cannot become disease later. (2) (3)
Always discuss dosing and treatment changes with your own prescriber.
Possible complications
- Lasting lung damage: Even after cure, TB can leave scarring, widened airways (bronchiectasis) and reduced lung function, causing a long-term cough and breathlessness. Early treatment reduces this. (1) (4)
- TB spreading through the body: Untreated TB can spread to the lymph glands, bones and spine (causing pain and, if the spine collapses, nerve damage), the kidneys, the lining of the heart or abdomen, and the brain (TB meningitis). Miliary TB is widespread infection through the bloodstream. These forms are serious and are why treatment must not be delayed. (2) (3)
- Drug-resistant TB: If treatment is incomplete or the wrong drugs are used, the bacteria can become resistant, which is harder, longer and more toxic to treat. Worldwide, only about 2 in 5 people with drug-resistant TB currently get the treatment they need. (1) (2)
- Medicine side effects: TB drugs can cause liver inflammation, rash, nerve tingling, joint pains, and, with ethambutol, changes in vision. These are monitored for and are usually manageable by adjusting the regimen. (3) (2)
- The global situation: TB remains the world's leading cause of death from a single infection. In 2024 an estimated 10.7 million people fell ill with TB and 1.23 million died, including many people also living with HIV. Most of this burden is in low- and middle-income countries, and TB is curable, so these deaths are largely preventable. (1)
When to see a doctor
Routine follow-up
- Book an appointment if you have a cough lasting more than 3 weeks, especially with weight loss, fever, night sweats or tiredness, or if you have any of these after spending time in a country where TB is common or with someone who has TB. (3) (2)
- Ask about testing for latent TB if you are a close contact of someone with TB, or before starting a medicine that weakens the immune system such as a biologic for arthritis or inflammatory bowel disease. (2) (3)
- See your TB team promptly if you are on TB treatment and develop yellow skin or eyes, a rash, tingling in the hands or feet, changes in vision, or side effects that make it hard to take the medicine. (3) (2)
Seek emergency care
- Call the emergency services now, 911 in the United States, 999 in the United Kingdom or 000 in Australia, if you cough up a large amount of blood, are severely breathless, or have a severe headache with a stiff neck, confusion or drowsiness and a fever. For a small amount of blood in phlegm, seek an urgent same-day appointment or medical helpline advice the same day. (3) (2) (1)
Frequently asked questions
Is tuberculosis curable?
Yes. Almost all drug-sensitive TB is cured by taking the full 6-month course of antibiotics. Even most drug-resistant TB can now be cured with a 6-month all-oral regimen. The key is to complete the whole course, even after you feel well. (3) (1) (2)
What is the difference between latent TB and active TB?
Latent TB infection means the bacteria are in your body but dormant. You have no symptoms, you feel well, and you cannot pass TB to anyone; only a skin or blood test is positive. Active TB disease means the bacteria are multiplying and making you ill, and lung or throat TB can spread to others. Latent TB can turn into active TB later, which is why it is often treated. (2) (3) (1)
How does TB spread, and is it easy to catch?
TB spreads through the air when a person with active lung or throat TB coughs, speaks or sings. It is not spread by touching surfaces, sharing food or cutlery, shaking hands or kissing. It usually needs close, repeated contact, such as living in the same household, so a brief encounter carries little risk. (2) (3) (1)
What are the first symptoms of TB in the lungs?
The usual first sign is a cough that lasts more than 3 weeks, sometimes with phlegm or blood. Weight loss, loss of appetite, a high temperature, drenching night sweats and persistent tiredness are also common. TB outside the lungs causes symptoms in the affected area, such as swollen neck glands or back pain. (3) (2) (1)
How is TB treated?
Drug-sensitive active TB is treated with 2 months of four antibiotics (isoniazid, rifampicin, pyrazinamide and ethambutol) then 4 months of two of them, for 6 months in total. A newer 4-month regimen is available in some countries. Latent TB is treated with a shorter course, often 3 to 4 months. Drug-resistant TB needs a longer, specialist regimen. (3) (2) (1)
How long is a person with TB infectious?
Most people with drug-sensitive lung TB are no longer infectious after about 2 weeks of effective treatment, provided their symptoms are improving and follow-up sputum tests are becoming negative. Your TB team will advise when it is safe to return to work, school or normal social contact. (3) (2)
Why do I have to take so many drugs for so long?
TB bacteria grow very slowly and hide inside cells, so short courses do not kill them all. Using several drugs together stops the bacteria becoming resistant. Stopping early is the main cause of relapse and of drug-resistant TB, which is much harder to treat. (2) (1)
Does the BCG vaccine protect me?
The BCG vaccine protects babies and young children well against severe TB, especially TB meningitis, but is less reliable against lung TB in adults. It is given to infants in many high-TB countries and to at-risk children in the UK and Australia, and is not used routinely in the US general population. (1) (3) (2)