What causes pulmonary fibrosis? 

Pulmonary fibrosis is a complex condition where the lung tissue becomes scarred and thickened over time. While the exact reason for this scarring is not always identifiable, researchers and medical professionals have pinpointed several environmental, medical, and lifestyle factors that can trigger the damage. In the United Kingdom, healthcare specialists categorise these causes into broad groups to help determine the most effective management plan for each patient. Identifying the underlying cause, where possible, is a vital part of the diagnostic journey and helps in understanding how the condition might progress. 

What We’ll Discuss in This Article 

• Environmental and occupational hazards that contribute to lung scarring. 

• Medical conditions, such as autoimmune diseases, linked to fibrosis. 

• Medications and treatments that may cause drug-induced lung damage. 

• The role of genetics and lifestyle factors in idiopathic cases. 

• How acid reflux and viral infections might impact lung health. 

Occupational and environmental exposures 

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One of the most well-documented causes of lung scarring involves long-term exposure to certain types of dust and fumes in the workplace. Inhaling irritants like silica, asbestos, and certain metal or wood dusts can cause inflammation that eventually leads to permanent scarring. This is particularly common in industries such as construction, mining, and farming. Organic substances, including bird droppings or mouldy hay, can also trigger an allergic-type reaction in the lungs known as hypersensitivity pneumonitis, which may lead to fibrosis if the exposure continues over many years. Reducing exposure to these triggers is a key part of preventing further lung damage for those in high-risk occupations. 

Underlying medical conditions 

Pulmonary fibrosis can sometimes develop as a secondary complication of another health issue, particularly autoimmune and connective tissue diseases. In these conditions, the body’s immune system mistakenly attacks its own tissues, including the delicate structures of the lungs. Conditions frequently associated with lung scarring include rheumatoid arthritis, systemic sclerosis (scleroderma), and systemic lupus erythematosus. When the immune system causes ongoing inflammation in the lungs, the natural healing process can result in the formation of scar tissue. Specialists in the UK often work in multidisciplinary teams to manage both the primary autoimmune condition and the resulting lung involvement. 

Drug-induced pulmonary fibrosis 

Certain medications used to treat other serious health conditions can, as a side effect, cause damage to the lungs. This is often referred to as drug-induced pulmonary fibrosis and can occur with several different types of drugs. Chemotherapy agents used in cancer treatment, certain heart medications like amiodarone, and some strong antibiotics are known to carry this risk. It is important to note that most people taking these medications do not develop lung scarring, but doctors monitor patients closely for any signs of respiratory changes. If a medication is suspected of causing lung damage, the clinical team will weigh the benefits of the treatment against the potential risks to respiratory health. 

Idiopathic and genetic factors 

In many cases, the cause of pulmonary fibrosis remains unknown even after extensive testing, which results in a diagnosis of idiopathic pulmonary fibrosis (IPF). While the primary trigger is unclear, several factors appear to increase the likelihood of developing the condition. Age is a significant factor, as IPF most commonly affects people over the age of 70 and is rare in those under 50. There is also evidence that genetics play a role, with approximately one in twenty people with IPF having another family member with the condition. NICE guidance focuses on the management of idiopathic pulmonary fibrosis by addressing these risk factors and providing targeted treatments to slow the rate of scarring. 

Lifestyle and other potential triggers 

Lifestyle choices and other common health issues may also contribute to the development or worsening of pulmonary fibrosis. Smoking is strongly linked to an increased risk of lung scarring and can make existing symptoms progress more quickly. Additionally, chronic gastro-oesophageal reflux disease (GORD), commonly known as acid reflux, is frequently observed in patients with pulmonary fibrosis. It is thought that small amounts of stomach acid may be inhaled into the lungs over time, causing micro-injury and inflammation that triggers a scarring response. Viral infections have also been investigated as potential triggers that might initiate the damage in susceptible individuals. 

Conclusion 

The causes of pulmonary fibrosis are diverse, ranging from clear occupational exposures to complex autoimmune responses and unknown idiopathic factors. Understanding these triggers allows for better monitoring and more personalised care within the UK healthcare system. Early identification of symptoms and risk factors remains the best way to ensure timely intervention and support. If you experience severe, sudden, or worsening symptoms, call 999 immediately. 

Authority Snapshot (E-E-A-T Block) 

This article explores the various medical and environmental causes of pulmonary fibrosis, ensuring all information is aligned with the standards of the NHS and NICE. The content is designed to provide the general public with a reliable overview of how lung scarring is understood and categorised in the UK. This educational resource has been produced by a medical content team and reviewed by Dr. Rebecca Fernandez, a UK-trained physician, to maintain clinical accuracy.