The exact cause of idiopathic pulmonary fibrosis (IPF) is not known. Idiopathic means having no known cause.

The current theory is that IPF is triggered when cells that line the lung alveoli (air sacs) become damaged by exposure to one of several substances or viruses.

The damaged cells try to repair themselves but the process becomes uncontrolled, resulting in thickening and scarring (fibrosis) of the alveoli and surrounding lung tissue. The amount of oxygen that can pass from the lungs into the blood is then significantly reduced.

Triggers

A number of factors have been suggested as possible triggers for the initial damage to the cells lining the alveoli. Most experts agree that the two most significant risk factors are:

• being a smoker or having smoked in the past
• occupational exposure to certain types of dust – jobs that involve working with wood, metal, textile, stone, cattle or farming may increase the risk of IPF 

Other possible risk factors include:

• viral infections – such as the Epstein-Barr virus or hepatitis C
• gastro-oesophageal reflux disease (GORD) (where the acid from your stomach rises back up into your throat) – this may be accidentally inhaled into the lungs, causing damage to the alveoli
• chronic aspiration – where food, drink or saliva enter the lungs and is not coughed back up, often due to a related condition
• environmental pollutants or dust
• genetic tendency – the condition appears to run in some families but this only seems to be the case in around 5% of people with IPF

As IPF is such a rare condition it is hard to estimate how much of an impact these risk factors can have on your chance of developing it.

Idiopathic pulmonary fibrosis (IPF) can be hard to diagnose because its main symptoms are similar to those of other lung diseases and the exact cause is not known.

You will usually be referred to a chest (respiratory) specialist in hospital for diagnosis. They will work closely with radiologists (specialists in X-rays and scans) and specialist lung nurses to help identify the cause of your symptoms.

In most areas, specialist interstital lung disease (ILD) centres have been identified and will be responsible for prescribing any medication you need, such as pirfenidone.

Medical history and physical examination

Your doctor will ask about your medical history and whether there are other factors that could contribute to the diagnosis of IPF, such as whether you:

• are a smoker
• have been exposed to occupational contaminants
• have other medical conditions

They will physically examine you and check the sound of your breathing through a stethoscope. A crackling sound can suggest fibrosis.

They will also look for thickening of tissue at the base of your fingers and toenails (digital clubbing).

Breathing tests

Lung function tests (also called pulmonary function tests) assess how well your lungs work. These tests measure:

• how quickly you can move air in and out of your lungs
• how much air they can hold
• how well they transfer oxygen into, and remove carbon dioxide from, your blood

The tests require you to breathe in and out of a lung function machine. Information collected will help diagnose different lung diseases, measure their severity and check how well treatment for a particular lung disease is working.

Chest X-ray

Chest X-rays are a good way of looking for changes or abnormalities in your lungs to help diagnose particular conditions. Although major organs and blood vessels do not show up as clearly on X-rays as bones, they are still visible.

CT scan

Similar to an X-ray, a CT (computerised tomography) scan can provide a sharper and more detailed image of your lungs.

Your radiologist may be able to identify a honeycomb effect in the lungs. This honeycomb effect suggests lung scarring and damage to your air sacs.

Further tests

If the initial exam, tests and scans could not confirm the diagnosis, your consultant may suggest further tests, such as:

• a bronchoscopy
• a lung biopsy (removing a small piece of your lung)

Bronchoscopy

Bronchoscopy is a method of looking inside your airways. A narrow, flexible tube called a bronchoscope is introduced through your nose or throat and down into your airways. The tube has an eyepiece so the doctor can see inside.

The doctor then looks for anything abnormal and can take cell samples for testing. They can also take photographs of the inside of your airways if necessary.

You usually have the test under local anaesthetic. This means you are awake for the test but your throat is numbed. The procedure can be a bit uncomfortable but does not last long.

Lung biopsy

A biopsy of the lung can usually be obtained using a keyhole procedure. The modern technique is called video-assisted thoracoscopic surgery, or VATS.

VATS is performed under a general anaesthetic, so you are asleep throughout. A surgeon makes several small incisions (cuts) in your side and an endoscope (a thin tube with a camera and a light at the end) is inserted into the area between the lungs and the chest wall.

The surgeon is able to see the lung tissue through the endoscope and obtain a sample, which can be examined under a microscope for signs of fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a rare and poorly understood lung condition that causes scarring of the lungs. 

Idiopathic means the cause of the condition is not known.

IPF gets worse over time and is often fatal.

Symptoms include:

• shortness of breath – especially when physically active – which gradually worsens over time
• a persistent dry cough

Read more about the symptoms of idiopathic pulmonary fibrosis.

What causes pulmonary fibrosis?

The cause of IPF is still unclear, but the condition appears to involve the cells that line the tiny air sacs in the lungs (alveoli). These are called alveolar epithelial cells (AECs).

The AECs appear to become damaged and begin to die. The body tries to repair the damage by releasing another type of cell known as fibroblasts. But the production of the fibroblasts goes out of control and they cause scarring and hardening (fibrosis) of the delicate tissues of the lungs.

As this scarring gets worse the lungs find it more difficult to work properly, resulting in the symptoms of IPF.

But exactly why the AECs become damaged in the first place isn’t clear. A combination of genetic and environmental factors may be involved.

Read more about the possible causes of idiopathic pulmonary fibrosis.

Treatment

There is currently no cure for IPF so the aim of treatment is to try to relieve symptoms and slow its progression.

Breathing oxygen through a mask and pulmonary rehabilitation – exercises and advice to help you breathe more easily – may be recommended to treat breathlessness. This is based on an assessment if you are diagnosed with IPF.

A medication called pirfenidone may be used for treating adults with IPF who have a lung capacity of 50-80% of the expected value.

Younger people with IPF who are in a relatively good state of health may be suitable candidates for a lung transplant.

Read more about the treatment of idiopathic pulmonary fibrosis.

Who is affected

IPF is a relatively rare condition, although the number of cases has risen in recent years. It is estimated that more than 5,000 cases are diagnosed every year in the UK.

The condition usually first develops in adults aged 50 or above and is thought to be more common in men.

Outlook

The outlook for IPF can be highly variable. Some people respond well to treatment and remain relatively free of symptoms for many years.

Other people’s health quickly worsens leading to a fatal complication, such as heart failure.

It is impossible to predict an individual’s expected survival rate as the rate of progression can vary greatly.

In the UK, the average survival for people with IPF is three years from the time of diagnosis. However, around 20% of people with the disease survive for more than five years.

The most common symptom of idiopathic pulmonary fibrosis (IPF) is shortness of breath, often when physically active, which can get worse over time.

At first, many people ignore their breathlessness (especially older patients) and blame it on getting old or being out of shape. But as the disease progresses and lung damage becomes more severe, even light activity like getting dressed or having a shower can cause breathlessness.

Other symptoms of pulmonary fibrosis include:

• a persistent dry cough
• tiredness
• loss of appetite and weight loss

In up to half of all cases, there is also a change in the shape of the finger and toenails. This thickening of tissue at the base of the finger and toenails is known as digital clubbing. The exact cause of clubbing is unknown, but it can occur in people with various chest and heart diseases.

Secondary conditions

The strain IPF can place on your lungs and your heart can trigger a number of secondary conditions, outlined below.

Chest infection

You will have an increased risk of developing chest and airway infections such as:

• bronchitis – an infection of the airway of the lungs
• pneumonia – an infection of the air sacs of your lungs
• influenza (flu)

Symptoms of a chest infection include:

• worsening breathlessness
• chest pain
• a high temperature (fever) of 38C (100.4F) or above 
• sweating and shivering

Pulmonary hypertension

Around a third of people with IPF will also go on to develop pulmonary hypertension. Pulmonary hypertension is when blood pressure inside the arteries connecting the lungs to the heart is dangerously high.

Symptoms of pulmonary hypertension include:

• dizziness
• feeling faint
• chest pain (angina)
• a racing heartbeat (tachycardia)

Read more about symptoms of pulmonary hypertension.

Heart failure

Heart failure, where the heart is unable to pump enough blood around the body, can develop when IPF becomes severe.

This is due to a combination of factors, including a build-up of blood in the right side of the heart (the side that pumps blood to the lungs), which develops because it is difficult to pump blood through the scarred lung tissue. The poor supply of oxygen from the diseased lungs to the heart muscle also contributes to heart failure.

Heart failure can cause various symptoms, including:

• worsening breathlessness
• extreme tiredness and weakness
• swelling in the legs, ankles and feet (oedema) caused by a build-up of fluid

Read more about the symptoms of heart failure.

There is currently no cure for idiopathic pulmonary fibrosis (IPF). The main aim of treatment is to relieve symptoms of the disease as much as possible and slow down its progression.

The best treatment will depend on how severe your illness is and your own preferences.

You may also need treatment for any other conditions you have. In some cases, you may need to stop certain treatments if they are not working or if you experience severe side effects.

Self care

As well as medical treatments, there are measures you can take to stay as healthy as possible:

• stop smoking
• exercise regularly and stay as fit as you can
• eat a healthy, balanced diet
• make sure you get the flu and pneumococcal vaccinations (influenza and pneumococcal infections can become severe if you have a lung disease)
• try to keep away from people with chest infections and colds

Treating breathlessness

If you get out of breath regularly, your doctor may recommend you are assessed for either:

• oxygen support
• pulmonary rehabilitation

Oxygen support

When IPF is severe, levels of oxygen in your blood fall and you feel more breathless. In this case your specialist may prescribe you oxygen, which can help with your breathing and enable you to be more active.

You will need to take oxygen through nasal tubes or a mask from a portable machine called an oxygen concentrator. This device provides air with a much higher oxygen level than the air you breathe in naturally. The tubes from the machine are long, so you will be able to move around your home while connected.

Read more information about home oxygen treatment.

You can also use an oxygen inhaler when you are out and about.

Pulmonary rehabilitation

Pulmonary rehabilitation is used for many long-term lung conditions and aims to help patients come to terms with their condition, learn the best ways to deal with it and improve their ability to function on a daily basis without extreme breathlessness.

Courses in pulmonary rehabilitation are usually held locally and may include:

• education about pulmonary fibrosis
• physical exercise
• breathing exercises
• advice on nutrition
• psychological support
• a social support network

For more information, watch the video on this page in which a respiratory nurse specialist and patients explain pulmonary rehabilitation.

Medication

Medication can help reduce symptoms of IPF in some people, but they’re not suitable for everyone.

Some people, particularly elderly people whose symptoms are mild or not getting worse, may be advised not to take any medication. This is because possible side effects could be worse than the progression of the disease.

The medications your doctor may recommend to treat IPF include:

• pirfenidone
• N-acetylcysteine
• nintedinib

Pirfenidone

Pirfenidone helps to slow the development of scarring in the lungs by suppressing the immune system.

The National Institute for Health and Care Excellence (NICE) recommends that pirfenidone may be used for treating adults with IPF who have a lung capacity of 50-80% of the expected value.

If your disease gets worse and your lung capacity falls by 10% or more within a year, then pirfenidone should be stopped.

Side effects of pirfenidone may include:

• nausea
• vomiting
• diarrhoea
• abdominal pain
• tiredness (fatigue)
• photosensitivity rash (on exposure to sunlight)

Read the NICE guidelines on pirfenidone for idiopathic pulmonary fibrosis (PDF, 161kb).

N-acetylcysteine

N-acetylcysteine is what is known as an antioxidant. There is currently some limited evidence to suggest this medication can reduce the amount of scar tissue created in the lungs.

N-acetylcysteine is available from many health shops on an over-the-counter basis and is taken as tablets, sometimes dissolved in water.

Check with the doctor in charge of your care before taking this medication as it may not be safe or suitable for everyone with IPF.

Nintedinib

Nintedinib is a newer medication, known as an anti-fibrotic kinase inhibitor, which has shown promising results in recent trials.

Although it is currently unlicensed, certain people with IPF may be offered nintedinib if their doctor thinks they could benefit from using it.

Lung transplant

If your condition continues to get worse despite other forms of treatment, your consultant may recommend a lung transplant. The decision to have a transplant will be based on:

• how bad your condition is
• how quickly your condition is getting worse
• your age and general health
• how much your condition is likely to improve after a transplant
• whether a donor lung is available

Few people with idiopathic pulmonary fibrosis are suitable candidates for a lung transplant.