Pulmonary fibrosis is the scarring of lung tissue — a process that stiffens the lungs, reduces their capacity to transfer oxygen, and in its most common form, progresses without stopping.
The most important subtype is idiopathic pulmonary fibrosis (IPF), where no external cause can be identified. The lung tissue is replaced by dense fibrous scar. Once formed, scar tissue does not reverse. The goals of treatment are to slow the scarring, preserve function, and manage symptoms — not to cure. Two antifibrotic drugs, nintedanib and pirfenidone, reduce the annual rate of lung function decline by roughly half.
Untreated IPF patients lose roughly 220 mL of FVC per year; on antifibrotic therapy, that loss is approximately 110 mL per year — about half. Over 5 years, this difference is the difference between meaningful exercise capacity and oxygen dependence.
INPULSIS-1 and -2 reported nintedanib reduced annual FVC decline by ~110 mL versus placebo. ASCEND pooled with CAPACITY showed pirfenidone reduced ≥10% FVC decline by ~48%.
Pulmonary fibrosis is scarring (fibrosis) of the lung parenchyma — the tissue responsible for gas exchange. When the interstitium scars, the alveolar walls thicken, the lungs lose compliance, and oxygen transfer becomes impaired. IPF is defined by a specific CT pattern (usual interstitial pneumonia, UIP) and the absence of a known cause. Other forms — CTD-associated, drug-induced, hypersensitivity pneumonitis-related — share the same end-stage pathology but have different treatment implications.
Progressive exertional dyspnea is the hallmark — patients describe climbing stairs as progressively harder over months to years. Dry, nonproductive cough is common. On examination, fine inspiratory crackles at the lung bases — described as "Velcro" crackles — are nearly universal. Finger clubbing develops in advanced disease. Patients often attribute early symptoms to aging or deconditioning and present 1–2 years after symptom onset.
A high-resolution CT chest is the cornerstone. The UIP pattern — subpleural and basal predominant reticulation, honeycombing with or without peripheral traction bronchiectasis — is diagnostic in the right clinical context. When CT is indeterminate, multidisciplinary discussion (pulmonologist, radiologist, pathologist) is the gold standard. Surgical lung biopsy is reserved for cases where the histologic pattern would materially change management. PFTs typically show a restrictive pattern with reduced DLCO.
Two antifibrotic agents are FDA-approved for IPF: nintedanib (Ofev) and pirfenidone (Esbriet). Both reduce FVC decline by approximately 50% relative to placebo. They do not reverse existing fibrosis, but they meaningfully slow progression. Treatment should start as early as possible — the effect size is larger when baseline function is better preserved. Supplemental oxygen for exertional hypoxia, pulmonary rehabilitation, anti-reflux therapy, and aggressive vaccination are standard supportive measures. Lung transplant evaluation should be initiated in eligible patients at the time of diagnosis, not at end-stage.
This page is general medical information, not personalized medical advice. If you have questions about your specific health, talk with your Nimbus clinician.
