Tuberculosis (TB)


Tuberculosis (TB)
Tuberculosis (TB)

Tuberculosis (TB) is a bacterial infection spread through inhaling tiny droplets from the coughs or sneezes of an infected person.

It mainly affects the lungs, but it can affect any part of the body, including the tummy (abdomen) glands, bones and nervous system.

TB is a serious condition, but it can be cured if it's treated with the right antibiotics.

Symptoms of TB

Typical symptoms of TB include:

  • a persistent cough that lasts more than 3 weeks and usually brings up phlegm, which may be bloody
  • weight loss
  • night sweats
  • high temperature
  • tiredness and fatigue
  • loss of appetite
  • swellings in the neck

You should see a GP if you have a cough that lasts more than 3 weeks or you cough up blood.

Read more about the symptoms of TB and diagnosing TB.

What causes TB?

TB is a bacterial infection. TB that affects the lungs (pulmonary TB) is the most contagious type, but it usually only spreads after prolonged exposure to someone with the illness.

In most healthy people, the body's natural defence against infection and illness (the immune system) kills the bacteria and there are no symptoms.

Sometimes the immune system cannot kill the bacteria, but manages to prevent it spreading in the body.

You will not have any symptoms, but the bacteria will remain in your body. This is known as latent TB. People with latent TB are not infectious to others.

If the immune system fails to kill or contain the infection, it can spread within the lungs or other parts of the body and symptoms will develop within a few weeks or months. This is known as active TB.

Latent TB could develop into an active TB disease at a later date, particularly if your immune system becomes weakened.

Read more about the causes of TB.

Treating TB

With treatment, TB can almost always be cured. A course of antibiotics will usually need to be taken for 6 months.

Several different antibiotics are used because some forms of TB are resistant to certain antibiotics.

If you're infected with a drug-resistant form of TB, treatment with 6 or more different medications may be needed.

If you're diagnosed with pulmonary TB, you'll be contagious for about 2 to 3 weeks into your course of treatment.

You will not usually need to be isolated during this time, but it's important to take some basic precautions to stop the infection spreading to your family and friends.

You should:

  • stay away from work, school or college until your TB treatment team advises you it's safe to return
  • always cover your mouth when coughing, sneezing or laughing
  • carefully dispose of any used tissues in a sealed plastic bag
  • open windows when possible to ensure a good supply of fresh air in the areas where you spend time
  • avoid sleeping in the same room as other people

If you're in close contact with someone who has TB, you may have tests to see whether you're also infected. These can include a chest X-rayblood tests, and a skin test called the Mantoux test.

Read more about treating TB.

Vaccination for TB

The BCG vaccine offers protection against TB, and is recommended on the NHS for babies, children and adults under the age of 35 who are considered to be at risk of catching TB.

The BCG vaccine isn't routinely given to anyone over the age of 35 as there's no evidence that it works for people in this age group.

At-risk groups include:

  • children living in areas with high rates of TB
  • people with close family members from countries with high TB rates
  • people going to live and work with local people for more than 3 months in an area with high rates of TB

If you're a healthcare worker or NHS employee and you come into contact with patients or clinical specimens, you should also have a TB vaccination, irrespective of age, if:

  • you haven't been previously vaccinated (you do not have a BCG scar or the relevant documentation), and
  • the results of a Mantoux skin test or a TB interferon gamma release assay (IGRA) blood test are negative

Read more about who should have the BCG vaccine.

Countries with high TB rates

Parts of the world with high rates of TB include:

  • Africa – particularly sub-Saharan Africa (all the African countries south of the Sahara desert) and west Africa
  • southAsia – including India, Pakistan, Indonesia and Bangladesh
  • Russia
  • China
  • South America
  • the western Pacific region (to the west of the Pacific Ocean) – including Vietnam, Cambodia and the Philippines

GOV.UK has detailed information on each country's TB rates.


The symptoms of tuberculosis (TB) vary depending on which part of the body is affected.

TB disease usually develops slowly, and it may take several weeks for you to become aware that you're unwell.

Your symptoms might not begin until months or even years after you were initially infected.

Sometimes the infection does not cause any symptoms. This is known as latent TB.

It's called active TB if you have symptoms. However, in some cases, symptoms might not develop until months or even years after the initial infection.

Contact a GP if you or your child have symptoms of TB.

General symptoms of TB

  • lack of appetite and weight loss
  • a high temperature
  • night sweats
  • extreme tiredness or fatigue

These symptoms can have many different causes, however, and are not always a sign of TB.

TB that affects the lungs (pulmonary TB)

Most TB infections affect the lungs, which can cause:

  • a persistent cough that lasts more than 3 weeks and usually brings up phlegm, which may be bloody
  • breathlessness that gradually gets worse

TB outside the lungs

Less commonly, TB infections develop in areas outside the lungs, such as the small glands that form part of the immune system (the lymph nodes), the bones and joints, the digestive system, the bladder and reproductive system, and the brain and nerves (the nervous system).

Symptoms can include:

TB affecting other parts of the body is more common in people who have a weakened immune system.

Who can get it

Tuberculosis (TB) is caused by a type of bacterium called Mycobacterium tuberculosis.

It's spread when a person with active TB disease in their lungs coughs or sneezes and someone else inhales the expelled droplets, which contain TB bacteria.

Although TB is spread in a similar way to a cold or flu, it is not as contagious.

You would have to spend prolonged periods (several hours) in close contact with an infected person to catch the infection yourself.

For example, TB infections usually spread between family members who live in the same house. It would be highly unlikely for you to become infected by sitting next to an infected person on, for instance, a bus or train.

Not everyone with TB is infectious. Children with TB or people with a TB infection that occurs outside the lungs (extrapulmonary TB) do not spread the infection.

Latent or active TB

In most healthy people, the immune system is able to destroy the bacteria that cause TB.

But in some cases, the bacteria infect the body but don't cause any symptoms (latent TB), or the infection begins to cause symptoms within weeks, months or even years (active TB).

Up to 10% of people with latent TB eventually develop active TB years after the initial infection.

This usually happens either within the first year or 2 of infection, or when the immune system is weakened – for example, if someone is having chemotherapy treatment for cancer.

Who's most at risk?

Anyone can get TB, but those at greatest risk include people:

  • who live in, come from, or have spent time in a country or area with high levels of TB – around 3 in every 4 TB cases in the UK affect people born outside the UK
  • in prolonged close contact with someone who's infected
  • living in crowded conditions
  • with a condition that weakens their immune system, such as diabetes
  • having treatments that weaken the immune system, such as chemotherapy or biological agents
  • who are very young or very old – the immune systems of people who are young or elderly tend to be weaker than those of healthy adults
  • in poor health or with a poor diet because of lifestyle and other problems, such as drug misuse, alcohol misuse, or homelessness


Several tests are used to diagnose tuberculosis (TB), depending on the type of TB suspected.

A GP may refer you to a TB specialist for testing and treatment if they think you have TB.

Pulmonary TB

Diagnosing pulmonary TB – TB that affects the lungs – can be difficult, and several tests are usually needed.

You may have a chest X-ray to look for changes in the appearance of your lungs that are suggestive of TB. Samples of phlegm will also often be taken and checked for the presence of TB bacteria.

These tests are important in helping to decide the most effective treatment for you.

Extrapulmonary TB

Several tests can be used to confirm a diagnosis of suspected extrapulmonary TB, which is TB that occurs outside the lungs.

These tests include:

  • CT scanMRI scan or ultrasound scan of the affected part of the body
  • an examination of the inside of your body using a long, thin, flexible tube with a light and camera at one end (endoscopy) – the endoscope can be inserted through a natural opening, such as your mouth, or through a small cut made in your skin (laparoscopy) if there's a need to check other parts of your body
  • urine and blood tests
  • biopsy – a small sample of tissue or fluid is taken from the affected area and tested for TB bacteria

You may also have a lumbar puncture, where a small sample of cerebrospinal fluid (CSF) is taken from the base of your spine. CSF is fluid that surrounds the brain.

The sample can be checked to see whether TB has infected your brain and spinal cord (central nervous system).

Testing for latent TB

In some circumstances, you may need to have a test to check for latent TB – where you've been infected with TB bacteria, but do not have any symptoms.

For example, you may need to have a test if you've been in close contact with someone known to have active TB disease involving the lungs, or if you've recently spent time in a country where TB levels are high.

If you've just moved to the UK from a country where TB is common, you should be given information and advice about the need for testing. Your GP may suggest having a test when you register as a patient.

Mantoux test

The Mantoux test is a widely used test for latent TB. It involves injecting a small amount of a substance called PPD tuberculin into the skin of your forearm. It's also called the tuberculin skin test (TST).

If you have a latent TB infection, your skin will be sensitive to PPD tuberculin and a small, hard red bump will develop at the site of the injection, usually within 48 to 72 hours of having the test.

If you have a very strong skin reaction, you may need a chest X-ray to confirm whether you have active TB disease.

If you do not have a latent infection, your skin will not react to the Mantoux test. However, as TB can take a long time to develop, you may need to be screened again at a later stage.

If you've had the BCG vaccination, you may have a mild skin reaction to the Mantoux test. This does not necessarily mean you have latent TB.

Interferon gamma release assay (IGRA)

The interferon gamma release assay (IGRA) is a blood test for TB that's becoming more widely available.

The IGRA may be used to help diagnose latent TB:

  • if you have a positive Mantoux test
  • if you previously had the BCG vaccination – the Mantoux test may not be reliable in these cases
  • as part of your TB screening if you've just moved to the UK from a country where TB is common
  • as part of a health check when you register with a GP
  • if you're about to have treatment that will suppress your immune system
  • if you're a healthcare worker


Treatment for tuberculosis (TB) usually involves taking antibiotics for several months.

While TB is a serious condition that can be fatal if left untreated, deaths are rare if treatment is completed.

Most people don't need to be admitted to hospital during treatment.

Pulmonary TB

You'll be prescribed at least a 6-month course of a combination of antibiotics if you're diagnosed with active pulmonary TB, where your lungs are affected and you have symptoms.

The usual treatment is:

  • 2 antibiotics (isoniazid and rifampicin) for 6 months
  • 2 additional antibiotics (pyrazinamide and ethambutol) for the first 2 months of the 6-month treatment period

It may be several weeks before you start to feel better. The exact length of time will depend on your overall health and the severity of your TB.

After taking antibiotics for 2 weeks, most people are no longer infectious and feel better.

However, it's important to continue taking your medicine exactly as prescribed and to complete the whole course of antibiotics.

Taking medication for 6 months is the best way to ensure the TB bacteria are killed.

If you stop taking your antibiotics before you complete the course or you skip a dose, the TB infection may become resistant to the antibiotics.

This is potentially serious because it can be difficult to treat and will require a longer course of treatment with different, and possibly more toxic, therapies.

If you find it difficult to take your medicine every day, your treatment team can work with you to find a solution.

This may include having regular contact with your treatment team at home, at the treatment clinic, or somewhere else that's more convenient.

If treatment is completed correctly, you should not need any further checks by a TB specialist afterwards. You may be given advice about spotting signs that the illness has returned, although this is rare.

Extrapulmonary TB

Extrapulmonary TB – TB that occurs outside the lungs – can be treated using the same combination of antibiotics as those used to treat pulmonary TB.

If you have TB in areas like your brain or the sac surrounding your heart (pericardium), you may initially be prescribed a corticosteroid such as prednisolone for several weeks to take at the same time as your antibiotics. This will help reduce any swelling in the affected areas.

As with pulmonary TB, it's important to take your medicines exactly as prescribed and to finish the whole course.

Multidrug-resistant TB

Though uncommon in the UK there are strains of TB that are resistant to 2 or more antibiotics. This is known as multidrug-resistant TB.

Multidrug-resistant TB requires a much longer course of antibiotics; between 9 to 24 months depending on the strain. Multidrug-resistant TB tends to have less favourable outcomes than standard TB.

Latent TB

Latent TB is where you've been infected with the TB bacteria, but do not have any symptoms of active infection.

If you have latent TB and are aged 65 or under, treatment is usually recommended. However, the antibiotics used to treat TB can cause liver damage in older adults.

If liver damage is a concern and you're aged between 35 and 65, your TB team will discuss with you the advantages and disadvantages of taking treatment for latent TB.

Latent TB is also not always treated if it's thought to be drug resistant. If this is the case, you may be regularly monitored to check the infection does not become active.

In some cases, testing and treatment for latent TB may be recommended for people who require treatment that will weaken their immune system, such as long-term corticosteroids, chemotherapy or biological inhibitors like TNF inhibitors. This is because there's a risk of the infection becoming active.

Treatment for latent TB generally involves:

  • either taking a combination of rifampicin and isoniazid for 3 months,
  • or isoniazid on its own for 6 months

Side effects of treatment

Isoniazid can cause nerve damage (peripheral neuropathy). You'll be given supplements of vitamin B6 (pyridoxine) to take alongside it to reduce this risk. Your liver function will be tested before you start treatment.

In rare cases, the antibiotics used to treat TB can cause eye damage, which can be serious. If you're going to be treated with ethambutol, your sight should also be tested at the beginning of the course of treatment.

Contact your TB treatment team if you develop any worrying symptoms during treatment, such as:

  • being sick
  • yellowing of your skin and the whites of your eyes (jaundice)
  • an unexplained high temperature (fever)
  • tingling or numbness in your hands or feet
  • a rash or itchy skin
  • changes to your vision, such as blurred vision

Rifampicin can reduce the effectiveness of some types of contraception, such as the combined contraceptive pill. You should use an alternative method of contraception, such as condoms, while taking rifampicin.

Rifampicin can also interact with other medication, so it's important that your TB team know about all of the medicine you're taking before you start treatment for TB.

Preventing the spread of infection

If you're diagnosed with pulmonary TB, you'll be contagious up to about 2 to 3 weeks into your course of treatment.

You won't usually need to be isolated during this time, but it's important to take some basic precautions to stop TB spreading to your family and friends.

You should:

  • stay away from work, school or college until your TB treatment team advises you it's safe to return
  • always cover your mouth – preferably with a disposable tissue – when coughing, sneezing or laughing
  • carefully dispose of any used tissues in a sealed plastic bag
  • open windows when possible to ensure a good supply of fresh air in the areas where you spend time
  • not sleep in the same room as other people – you could cough or sneeze in your sleep without realising it

What if someone I know has TB?

When someone is diagnosed with TB, their treatment team will assess whether other people are at risk of infection.

This may include close contacts, such as people living with the person who has TB, as well as casual contacts, such as work colleagues and social contacts.

Anyone who's thought to be at risk will be asked to go for testing, and will be given advice and any necessary treatment after their results.

The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website
Last Updated: 28/10/2022 14:16:32