Interstitial lung disease is a large group of disorders in which inflammation and/or scarring (fibrosis) thickens the interstitium — the tissue between the alveoli and the capillaries. The thickened wall slows oxygen diffusion, and the stiff lung is hard to expand. The result is a restrictive pattern: small lung volumes, reduced compliance, and hypoxemia that worsens with exertion. Unlike COPD, airflow is not obstructed.
| Group | Examples | Key clue |
|---|
| Idiopathic pulmonary fibrosis (IPF) | Most common idiopathic ILD | Older adult (usually > 60), often a former smoker, male; progressive and irreversible |
| Connective tissue disease–associated ILD (CTD-ILD) | Rheumatoid arthritis, systemic sclerosis, myositis, Sjögren syndrome | Known autoimmune disease + new dyspnea |
| Exposure-related | Hypersensitivity pneumonitis (birds, molds, hot tubs); pneumoconioses — silicosis, asbestosis, coal workers' pneumoconiosis | Occupational or home exposure history |
| Drug- or radiation-induced | Amiodarone, methotrexate, nitrofurantoin, bleomycin, immune checkpoint inhibitors, chest radiation | New cough/dyspnea after starting a drug or treatment |
| Sarcoidosis | Noncaseating granulomas in lungs, lymph nodes, skin, eyes, heart | Young to middle-aged adult; bilateral hilar lymph node enlargement |
IPF is the prototype fibrotic ILD: repeated microinjury to alveolar cells triggers abnormal repair, fibroblast proliferation, and collagen deposition, producing a "honeycomb" lung. Median survival without treatment has historically been about 3–5 years after diagnosis. Other ILDs can also become progressive pulmonary fibrosis (PPF) when at least two of three (worsening symptoms, decline in lung function, radiologic progression) occur within a year without another explanation.
Sarcoidosis is often discovered incidentally on a chest X-ray in a person without symptoms; many cases resolve spontaneously.
Subjective
- Gradually progressive dyspnea on exertion over months
- Dry, nonproductive cough
- Fatigue, weight loss
- Joint pain, skin changes, Raynaud phenomenon, dry eyes/mouth (suggest CTD-ILD)
- Detailed exposure history: occupation (mining, sandblasting, stone cutting, construction, shipbuilding), birds, mold, medications, radiation
Objective
- Fine, dry "Velcro-like" inspiratory crackles at the lung bases — classic in IPF
- Digital clubbing
- Tachypnea with shallow breaths; SpO₂ that drops with walking
- Late: central cyanosis, signs of pulmonary hypertension and right heart failure (JVD, peripheral edema, loud P2)
- Sarcoidosis extra-pulmonary signs: erythema nodosum (tender red shin nodules), uveitis, arrhythmias
Dyspnea measurement: use a standardized scale such as the modified Medical Research Council (mMRC) dyspnea scale or the Borg scale, alongside objective tests.
| Test | Key finding |
|---|
| High-resolution CT (HRCT) | Main diagnostic test. IPF = usual interstitial pneumonia pattern: basal, subpleural reticulation, traction bronchiectasis, honeycombing |
| Pulmonary function tests | Restrictive: ↓FVC and ↓total lung capacity, FEV₁/FVC normal or high; ↓DLCO (diffusing capacity) |
| 6-minute walk test | Distance and exertional desaturation; guides oxygen prescription |
| Pulse oximetry / ABG | Hypoxemia, often with low PaCO₂ from tachypnea; worsens with exercise |
| Serologies | ANA, rheumatoid factor, anti-CCP, myositis antibodies to find CTD-ILD |
| Bronchoscopy with lavage, transbronchial or surgical/cryobiopsy | When HRCT is not diagnostic |
| Serum ACE, calcium (sarcoidosis) | ACE often elevated (supports but does not confirm diagnosis); hypercalcemia and hypercalciuria can occur |
| Echocardiogram | Screens for pulmonary hypertension |
Diagnosis is made by a multidisciplinary discussion (pulmonologist, radiologist, pathologist).
Antifibrotic drugs (IPF and progressive pulmonary fibrosis) — slow the decline in lung function; they do not reverse scarring.
| Drug | Key adverse effects | Nursing safety points |
|---|
| Nintedanib | Diarrhea (very common), nausea, ↑liver enzymes, bleeding risk | Take with food; check liver tests before and regularly during therapy; antidiarrheal plan and hydration; caution with anticoagulants and recent bleeding; embryo-fetal toxicity — effective contraception |
| Pirfenidone | Photosensitivity rash, nausea, anorexia, ↑liver enzymes | Take with food; broad-spectrum sunscreen and protective clothing; check liver tests; avoid strong CYP1A2 inhibitors (e.g., fluvoxamine); smoking lowers drug levels |
| Nerandomilast (oral PDE4B inhibitor, approved 2025 for IPF and PPF) | Diarrhea (most common), nausea, decreased appetite, weight loss, depression or mood change | Monitor weight; ask about mood and report low mood or suicidal thoughts. Interactions: dose is reduced with strong CYP3A inhibitors; avoid moderate/strong CYP3A inducers (e.g., rifampin, carbamazepine, St John's wort). Taken with or without food; may be combined with nintedanib or pirfenidone |
Corticosteroids and immunosuppressants
- Not used for stable IPF — long-term prednisone with azathioprine increased harm in trials
- Used for sarcoidosis (when symptomatic or organs threatened), hypersensitivity pneumonitis, CTD-ILD, drug-induced ILD, and commonly for acute exacerbations of IPF (though evidence there is limited)
- Steroid safety: hyperglycemia, infection, osteoporosis, mood change, GI bleeding, adrenal suppression — taper, never stop abruptly
- Immunosuppressants (mycophenolate, methotrexate, azathioprine, rituximab): monitor CBC and liver tests; infection risk; methotrexate and mycophenolate are teratogenic
Remove the cause: stop the offending drug; avoid the antigen (birds, mold) in hypersensitivity pneumonitis; end dust exposure in pneumoconiosis.
Supportive
- Supplemental oxygen for resting or exertional hypoxemia; flow often must be higher during activity
- Pulmonary rehabilitation
- Vaccinations (influenza, pneumococcal, COVID-19, RSV)
- Treat pulmonary hypertension, GERD, sleep apnea, and depression when present
- Lung transplantation — the only treatment that can extend survival substantially in advanced disease; refer early, since evaluation takes time
- Palliative care for refractory dyspnea (e.g., low-dose opioids, fan to the face)
Listed in priority order.
- Oxygenation
- Monitor SpO₂ at rest and during activity; titrate oxygen to the prescribed target
- Deliver the prescribed flow consistently — clients often under-use oxygen on exertion
- Position upright; pace activities to limit desaturation
- Monitor for deterioration
- Increasing dyspnea over days, new crackles, rising oxygen need, fever — possible acute exacerbation or infection; notify provider
- Signs of right heart failure: edema, JVD, weight gain
- Medication administration and monitoring
- Antifibrotics: liver tests, GI tolerance, weight, sun protection (pirfenidone), bleeding (nintedanib)
- Steroids: blood glucose, infection signs, bone health
- Breathing and energy conservation
- Pursed-lip and diaphragmatic breathing to control breathing rate during dyspnea
- Energy conservation: sit for tasks, plan rest periods, spread activities across the day
- Pulmonary rehabilitation
- Individualized, gradually progressive endurance and strength training (including upper limb) within tolerance, with oxygen as needed. High-intensity exercise beyond tolerance is not appropriate
- Nutrition — weight loss is common; small frequent high-calorie meals; manage GI effects of antifibrotics
- Psychosocial and end-of-life support — anxiety and depression are common; discuss goals of care early
- Oxygen safety: use the prescribed flow — do not adjust it yourself; no smoking or open flames; keep oxygen away from heat sources; use water-based lubricants, never petroleum-based products on lips, nostrils, or tubing
- Take pirfenidone with meals; wear sunscreen and cover skin outdoors
- Report diarrhea, yellowing skin or eyes, dark urine, or unusual bleeding (antifibrotics)
- Use reliable contraception with antifibrotics, methotrexate, or mycophenolate
- Avoid triggers: stop smoking; avoid birds, feather bedding, moldy environments if hypersensitivity pneumonitis is diagnosed
- Workplace dust prevention (silica, asbestos, coal): engineering controls first (wet cutting, ventilation, enclosure), then properly fitted respirators and protective equipment; attend medical surveillance; report symptoms early rather than keep working with exposure
- Stay up to date on vaccines; avoid crowds during peak respiratory virus season
- Continue daily activity and rehabilitation exercises within tolerance
- Sarcoidosis: regular eye exams (uveitis), avoid excess calcium or vitamin D supplements unless prescribed
- Know the warning signs of exacerbation: sudden worsening dyspnea, fever, increasing oxygen need
| Complication | What to watch for |
|---|
| Progressive respiratory failure | The usual end result of IPF — rising oxygen need, hypercapnia late |
| Acute exacerbation of IPF | Rapid worsening within a month, new bilateral opacities; high mortality |
| Pulmonary hypertension / cor pulmonale | Exertional syncope, edema, JVD, hepatomegaly |
| Pneumothorax | Sudden chest pain and dyspnea |
| Lung cancer | IPF and asbestosis increase risk; asbestos also causes mesothelioma |
| Tuberculosis | Silicosis markedly increases TB risk |
| Infection, VTE | Especially with immunosuppression and immobility |
- ILD = restrictive disease: ↓FVC, ↓TLC, ↓DLCO, normal or high FEV₁/FVC
- IPF triad: progressive exertional dyspnea, dry cough, basal Velcro crackles; clubbing common
- HRCT is the key diagnostic test; honeycombing = fibrosis
- Antifibrotics (nintedanib, pirfenidone, nerandomilast) slow but do not reverse IPF
- Nintedanib → diarrhea, liver toxicity, bleeding; pirfenidone → photosensitivity, take with food
- Steroids are not used for stable IPF but are used for sarcoidosis, hypersensitivity pneumonitis, CTD-ILD
- Oxygen: keep the prescribed flow, often higher with exertion; no petroleum products
- Rehabilitation is gradual and within tolerance, not high-intensity
- Sarcoidosis: often asymptomatic, found on chest X-ray; bilateral hilar nodes; ↑ACE; hypercalcemia
- Rheumatoid arthritis + new dyspnea → think CTD-ILD
- Pneumoconiosis prevention: exposure control and respirator use
- Lung transplant is the definitive option for end-stage disease
Country Notes
United States
- Workplace silica exposure is regulated by OSHA's respirable crystalline silica standard; nurses in occupational health support exposure monitoring and medical surveillance.
- Silicosis has re-emerged among engineered-stone countertop fabrication workers; ask about this occupation specifically.
Philippines
- Occupational histories should include mining, quarrying, and construction work, which are common sources of silica exposure.
- Because tuberculosis is common, a new interstitial pattern or cavitation requires TB evaluation before starting corticosteroids or immunosuppressants.