Written by Dr Fasihul Khan, Consultant Respiratory Physician and ILD specialist, providing expert guidance on interstitial lung disease.
Anti-fibrotic medications are commonly used in fibrotic lung disease, particularly pulmonary fibrosis. Many patients are offered these treatments after being told their condition is progressing, which naturally raises questions about benefit, timing, and side-effects.
These medications do not reverse scarring or provide immediate symptom relief. Instead, they are used to slow the rate at which lung function declines over time. Deciding when to start treatment depends on the underlying diagnosis and how the disease is behaving.
Key points
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Anti-fibrotic drugs slow disease progression, but do not reverse fibrosis
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They usually do not improve breathlessness
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Treatment decisions depend on diagnosis and evidence of progression over time
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Not all patients with fibrosis need treatment straight away
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Careful specialist assessment is important before starting therapy
What are anti-fibrotic medications?
There are currently two licensed anti-fibrotic medications available in the UK: nintedanib and pirfenidone. Both are taken orally on a daily basis and act through different biological pathways, but their overall effect is similar – they reduce the rate of lung function decline in progressive fibrotic disease. Anti-fibrotic therapy does not reverse established scarring. Its purpose is to slow progression rather than cure disease.
In the UK, both nintedanib and pirfenidone are licensed for the treatment of idiopathic pulmonary fibrosis (IPF). For non-IPF progressive fibrotic interstitial lung disease, nintedanib is currently licensed, whereas pirfenidone is not licensed for this broader indication.
When is anti-fibrotic therapy recommended?
In idiopathic pulmonary fibrosis, anti-fibrotic therapy is typically recommended once the diagnosis has been confidently established and national treatment criteria are met. In other fibrotic ILDs, including connective tissue disease-associated ILD and fibrotic hypersensitivity pneumonitis, treatment decisions are more nuanced and depend on evidence of progression over time.
Progression is not defined by a single scan or test result. It is assessed longitudinally, through trends in lung function, symptom trajectory, and changes on CT. Some patients with fibrosis remain stable for prolonged periods and may be managed with structured monitoring alone. Treatment is generally directed at progressive disease rather than the mere presence of scarring.
Decisions are individualised and balance the risk of future decline against treatment burden, tolerability, and overall health status.
What benefit should patients expect?
The principal measurable effect of anti-fibrotic therapy is a slowing of lung function decline, most often assessed using forced vital capacity (FVC). This benefit is usually demonstrated over months and years rather than days or weeks. Meaningful assessment of response usually requires several months of follow-up.
Most patients do not experience immediate improvement in breathlessness. The aim of treatment is preservation rather than reversal. Because of this, the benefit may feel less visible in day-to-day life. However, stabilising lung function trajectories is associated with improved longer-term outcomes, although individual prognosis varies.
Effectiveness is assessed through serial lung function measurements alongside clinical review. Stability following treatment initiation may represent therapeutic success.
How long is treatment continued?
Anti-fibrotic therapy is usually continued long-term, provided it is tolerated and there is on-going evidence that treatment is appropriate. Decisions about continuation are reviewed regularly in clinic.
If treatment is stopped, lung function typically returns to its underlying rate of decline. There is no evidence of sudden “rebound” worsening, but the protective effect of therapy is no longer present.
Side-effects and monitoring
Both nintedanib and pirfenidone can cause side-effects. Gastrointestinal symptoms are common, particularly with nintedanib. Photosensitivity rash and fatigue may occur with pirfenidone. Elevation of liver enzymes can occur with both and requires regular blood monitoring.
In many cases, side-effects are manageable with dose adjustment, supportive measures, or temporary interruption of treatment. Anti-fibrotics can sometimes be used alongside other therapies, including immunosuppressive treatment in selected patients, but this requires careful supervision.
Treatment decisions are revisited over time to ensure that benefit continues to outweigh burden.
The importance of specialist initiation
Anti-fibrotic therapy should be initiated and monitored within a specialist ILD service. Accurate classification of ILD subtype, confirmation of progression, and exclusion of alternative inflammatory phenotypes are essential before treatment begins.
In the UK, access to anti-fibrotic therapy within the NHS is governed by national funding criteria and specialist assessment. These medications are typically prescribed through tertiary centres following multidisciplinary team (MDT) discussion. This approach ensures that diagnosis is secure, progression criteria are appropriately met, and monitoring is conducted safely.
Since anti-fibrotics alter disease trajectory rather than symptoms alone, structured monitoring over time is essential.
Emerging therapies
Research in fibrotic lung disease continues to evolve. Nerandomilast, an oral phosphodiesterase inhibitor, has recently completed phase 3 trials in idiopathic pulmonary fibrosis and progressive pulmonary fibrosis, with data demonstrating a reduction in the rate of lung function decline. The medication is currently under regulatory review and is not yet licensed for routine clinical use in the UK.
Inhaled treprostinil has also been studied in fibrotic lung disease. Earlier trials demonstrated benefit in patients with pulmonary hypertension associated with ILD. More recently, the TETON programme evaluated inhaled treprostinil in IPF, irrespective of pulmonary hypertension status. Emerging data suggest potential effects on disease progression, although its precise role in fibrotic ILD and future regulatory positioning remain under review.
As additional therapies emerge, ILD management is likely to become increasingly individualised. Future strategies may involve earlier intervention, combination approaches, and more tailored decision-making based increasingly on disease behaviour rather than diagnostic label alone.
In addition to licensed and emerging therapies, clinical trials continue to play an important role in advancing treatment options for fibrotic ILD. Specialist centres often participate in national and international research studies evaluating novel medications and treatment strategies. Eligibility depends on diagnosis, disease stage, and previous therapy, and participation is considered carefully within a structured clinical framework. For selected patients, research involvement may provide access to developing therapies under specialist supervision.
When is additional specialist review helpful?
In the UK, anti-fibrotic therapy is initiated and monitored through specialist interstitial lung disease services. Patients who are offered treatment will already have undergone multidisciplinary assessment and structured evaluation before therapy begins.
However, additional specialist review can still be valuable in certain situations. In complex ILD, small differences in interpretation can influence management strategy. This may include uncertainty about diagnosis, questions regarding funding eligibility, whether disease truly meets progression thresholds, difficulty tolerating treatment, or consideration of clinical trial options. It can also be helpful in more complex cases, for example, when balancing immunosuppressive therapy and anti-fibrotic strategies.
In fibrotic ILD, treatment decisions are rarely based on a single scan or test result. They depend on diagnosis, disease behaviour over time, lung function trends, imaging evolution, symptom burden, and overall health status. Careful reassessment of these elements can sometimes clarify whether anti-fibrotic therapy is appropriate, whether timing is optimal, or whether an alternative strategy should be considered.
Structured evaluation ensures that treatment decisions are tailored to the individual rather than driven by terminology alone.