Tuberculosis (TB)

14 min read

What is 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 three weeks and usually brings up phlegm, which may be bloody
  • weight loss
  • night sweats
  • high temperature (fever)
  • tiredness and fatigue
  • loss of appetite
  • swellings in the neck

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

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 can't kill the bacteria, but manages to prevent it spreading in the body.

You won't have any symptoms, but the bacteria will remain in your body. This is known as latent TB. People with latent TB aren't 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.

Treating TB

With treatment, TB can almost always be cured. A course of antibiotics will usually need to be taken for six 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 six or more different medications may be needed.

If you're diagnosed with pulmonary TB, you'll be contagious for about two to three 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 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-ray , blood tests , and a skin test called the Mantoux test.

Tuberculosis symptoms

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 doesn't 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 your doctor if you or your child have symptoms of TB.

General symptoms of TB

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

These symptoms can have many different causes, however, and aren't 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 three 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:

  • persistently swollen glands
  • abdominal pain
  • pain and loss of movement in an affected bone or joint
  • confusion
  • a persistent headache
  • fits (seizures)

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

Tuberculosis causes

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 the flu , it isn't 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 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) don't 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 two 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 three in every four 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 HIV
  • 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

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
  • southeast Asia – 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

The World Health Organisation (WHO) has produced a world map showing countries with high rates of TB.

Tuberculosis diagnosis

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

Your doctor 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:

  • a CT scan , MRI 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
  • a 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 don't 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 doctor 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 don't have a latent infection, your skin won't 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 doesn't 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 doctor
  • if you're about to have treatment that will suppress your immune system
  • if you're a healthcare worker

Tuberculosis treatment

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 six-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:

  • two antibiotics (isoniazid and rifampicin) for six months
  • two additional antibiotics (pyrazinamide and ethambutol) for the first two months of the six-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 two 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 six 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 medication 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 shouldn't 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.

Latent TB

Latent TB is where you've been infected with the TB bacteria, but don't 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 doesn't 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 three months,
  • or isoniazid on its own for six 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 vision 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.

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.