What causes pleurisy?

The pleura is the lining of the outside of the lung and the inside of the ribcage (chest cavity). The area between the two surfaces of the pleura is called the pleural space. Usually, there is a very small amount of fluid in the pleural space (fewer than 10ml) which helps to lubricate the pleura when the lungs are expanding and contracting whilst breathing.

Pleurisy occurs when the pleura become inflamed.

There are several different causes of pleurisy, such as:

• Infections, for example:

  • Viral infections - the most common cause.

  • Bacterial pneumonia.

  • Tuberculosis.

  • Fungal infections.

• A blood clot in the lung (pulmonary embolism).

• A collapsed lung (pneumothorax).

• Injuries to the chest wall.

• Inflammation of the lining around the heart (pericarditis).

• Lung cancer.

• Inflammation caused by some types of inflammatory arthritis, like rheumatoid arthritis.

• A rare genetic condition, familial Mediterranean fever.

Pleurisy causes chest pain. Other causes of chest pain can cause similar symptoms to pleurisy, such as a heart attack. See the chest pain leaflet for more.

In this series of articles centred around pleurisy you can read about symptoms of pleurisy, pleurisy treatment, and pleurisy causes - all written by one of our expert GPs.

The rest of this feature will take an in-depth look at the causes of pleurisy as, at Patient, we know our readers sometimes want to have a deep dive into certain topics.

What causes pleurisy?

The most common cause of pleurisy is a bacterial or viral infection. Viral infections are most frequent and usually aren't serious - they get better with time. Other causes of pleurisy can be more serious.

Infection

Viral infections are the most common cause of pleurisy. People with viral pleurisy might have ae fever or other symptoms of a respiratory infection, such as a cough.

Viral infections can irritate the pleural lining, causing the pleura to become inflamed and rub against each other when breathing.

Viral pleurisy gets better after a few days without treatment and rarely causes any serious problems. Viruses that cause pleurisy include influenza and parainfluenza - which cause flu - coxsackieviruses, adenovirus, and respiratory syncytial virus (RSV). A virus called echovirus sometimes causes outbreaks of a rare condition called Bornholm disease, of which pleurisy is a part.

Other infectious causes of pleurisy can be more serious, and require treatment.

Bacterial infection (pneumonia), can irritate the pleura and cause pleurisy. Sometimes, a fluid build up, called a pleural effusion, can develop in the pleural space. These usually get better if the pneumonia is treated with antibiotics, but can sometimes require drainage with a needle or tube.

Bacterial infections can also infect the pleural space, causing a collection of pus in the pleural space (empyema). This pus needs to be drained, because antibiotics alone usually aren't enough to treat it.

Tuberculosis, which starts in the lung, can infect and irritate the pleural space, also causing a pleural effusion and pleurisy. Tuberculosis, and tuberculous pleurisy, is relatively rare in the UK, but is more common in some other countries.

Fungal infections can cause pneumonia and pleurisy. These usually only affect people with severely weakened immune systems, such as people with HIV/AIDS, or people who have had major chemotherapy.

Other causes of pleurisy

Other causes of pleurisy include:

• A blood clot in the lung (pulmonary embolism). This tends to be caused by blood clots that have lodged close to the pleura.

• A collapsed lung (pneumothorax). In this condition, air is trapped in the pleural space, and can irritate the pleura.

• Injuries to the chest wall. These can damage and irritate the pleura.

• Inflammation of the lining around the heart (pericarditis). This can cause similar symptoms to pleurisy, and sometimes the cause of pericarditis causes pleurisy as well.

• Lung cancer. Lung cancer that's near to the edge of the lung can irritate the pleura. It can also cause fluid to build up around the lung (pleural effusion).

• Some types of inflammatory (autoimmune) arthritis - also called connective tissue diseases - can cause inflammation in the pleura and pleurisy. For example, rheumatoid arthritis and systemic lupus erythematosus.

• A rare genetic condition called familial Mediterranean fever, which causes fevers and inflammation of tissues throughout the body, including the inside of joints, the lining of the abdomen, and the pleura.

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Risk factors for pleurisy

All of the causes of pleurisy have their own risk factors, though there are some risk factors that are shared between multiple causes. See the leaflets for each condition for more information about their risk factors.

In general, risk factors for pleurisy include:

• Age. Pleurisy can affect anyone, but older adults are more likely to get lung infections such as pneumonia.

• Smoking. Smoking increases the risk of various different causes of pleurisy, including pneumonia, pulmonary embolism, pneumothorax and lung cancer.

• Exposure to asbestos. This increases the risk of lung cancer, and of mesothelioma, cancer that develops from the pleura.

• Having a connective tissue disease, such as rheumatoid arthritis or systemic lupus erythematosus.