Causes of Pulmonary Fibrosis

Autoimmune diseases. In autoimmune diseases like rheumatoid arthritis, lupus, vasculitis, scleroderma… the immune system attacks its own respiratory system. 

Inhalation of foreign substances by the body, like certain types of dust, fungi, or contact with birds, which produce inflammation of the lungs that finally ends up as fibrosis (pneumonitis due to chronic hypersensitivity). 

Drugs, like sulphamides, nitrofurantoin, amiodarone, methotrexate, some monoclonal antibodies, or some types of chemotherapy, like bleomycin, which can initially inflame the lung (drug-induced-pneumonitis). 

Radiotherapy, in some areas of the chest. 

Occupational exposure, (to work exposed to asbestos, coal dust, cotton dust, wood dust, silica dust, dust from hard metals, etc.), that may lead to inflammation of the lung and that, after a prolonged time, can lead to lung fibrosis. 

Family history or genetic predisposition. Around 5% of IPF can be familial.

Smoking. Some fibrosing DILD are more common in smokers, such as IPF, or the combination of pulmonary fibrosis-emphysema. 

Age and gender. Some fibrosing DILD associated with autoimmune diseases are more common in women between 30-40 years-old. On the other hand, the majority of patients with IPF are men over 55 years-old. 

Type of work, hobbies, home environment. The duration of any exposures should be taken into account, and whether breathing protection has been used (masks).  

Previous treatments, such as chemotherapy or radiotherapy. There are many types of drugs capable of triggering a fibrosing DILD. 

Previous diseases. Some autoimmune diseases predispose the development of some fibrosing DILDs.