Drug induced pulmonary diseases are lung problems caused directly or indirectly by medicines. Any drug can cause lung injury in some people. The lung damage may be temporary or permanent depending on the type and how quickly it is recognised and treated.
Common patterns of lung injury
- Bronchospasm — sudden narrowing of airways causing wheeze and breathlessness.
- Pulmonary edema — fluid collects in the lungs (cardiogenic or non-cardiogenic).
- Pulmonary hypertension — high pressure in lung arteries.
- Interstitial lung disease (ILD) — inflammation or scarring of lung tissue (includes pneumonitis, fibrosis, BOOP).
- Pulmonary eosinophilia — allergic-type inflammation with many eosinophils.
- Pleural inflammation / effusion — fluid or inflammation around the lung.
- Diffuse alveolar hemorrhage (DAH) / vasculitis — bleeding into air spaces.
- Diffuse alveolar damage (DAD) — severe widespread injury, may lead to respiratory failure.
- Drug hypersensitivity syndrome (DHS) — systemic allergic reaction including pneumonitis.
- Specific toxicity — e.g., amiodarone lung toxicity.
Examples of drugs and typical effects (practical list)
- Bronchospasm: aspirin/NSAIDs (in sensitive people), beta-blockers (non-selective), penicillins or sulfonamides (allergic reactions), some excipients in inhalers. Management: stop offending drug, give bronchodilators, treat anaphylaxis if present.
- Pulmonary edema: excess IV fluids, contrast agents, some chemotherapy, IV beta-agonists in high dose. Management: supportive care, diuretics, oxygen, treat underlying cause.
- Pulmonary hypertension: appetite suppressants (fenfluramine), some amphetamines, rarely SSRIs — may need specialist therapy (prostacyclin analogues, endothelin receptor antagonists).
- Interstitial pneumonitis / fibrosis: bleomycin, busulfan, methotrexate, nitrofurantoin, some targeted cancer drugs and antiarrhythmics (amiodarone). Management: stop drug, give corticosteroids for many cases, supportive care.
- BOOP (organizing pneumonia): many drugs (antimicrobials, amiodarone, some chemotherapies). Presents with cough, fever, patchy infiltrates — responds to steroids.
- Pulmonary eosinophilia: caused by nitrofurantoin, minocycline, NSAIDs, some antimicrobials — diagnosis often needs eosinophils on blood or lung samples; treat with drug withdrawal and steroids if severe.
- Pleural disease: dantrolene, bromocriptine, nitrofurantoin and others can cause pleuritis or effusion — stop drug and treat symptoms.
- DAH / vasculitis: anticoagulants, thrombolytics, some chemotherapy and immunologic drugs — presents with hemoptysis and acute breathlessness; urgent supportive care and stop offending agent.
- Amiodarone pulmonary toxicity: often after many months; presents with cough, dyspnea and infiltrates — stop drug and give prolonged corticosteroids.
How these reactions usually present (what to look for)
- New or worsening cough, breathlessness or wheeze after starting a drug
- Fever, low-grade or high, with or without cough
- Chest pain (pleuritic), blood in sputum, or rapid breathing
- Hypoxia (low oxygen), abnormal chest X-ray or CT scan
- Timing varies — some reactions are immediate (minutes–hours), others appear months later
Diagnosis — practical steps
- Review drug history carefully (start dates, dose changes, OTC and herbal medicines).
- Exclude infections and other causes (work-up: chest X-ray/CT, sputum cultures, blood tests).
- Look for supporting tests: eosinophilia, raised inflammatory markers, abnormal gas exchange, abnormal imaging (diffuse infiltrates, fibrosis).
- Special tests: bronchoscopy with BAL, lung biopsy in difficult cases, pulmonary function tests for chronic changes.
- If drug is likely cause, stop it when safe and monitor closely.
Treatment — clear, practical approach
- Immediate: stop the suspected drug(s) if possible.
- Supportive care: oxygen, fluids/diuretics if pulmonary edema, ventilatory support for severe respiratory failure.
- Medications: systemic corticosteroids are commonly used for many inflammatory patterns (pneumonitis, BOOP, eosinophilia, amiodarone toxicity) — dose and duration depend on severity.
- Specific therapy: for pulmonary hypertension or vasculitis follow specialist-directed treatment (prostacyclins, endothelin antagonists, immunosuppressants).
- Treat complications: antibiotics for secondary infections, blood products for severe DAH, rehabilitation for chronic fibrosis.
Monitoring and follow-up
- Baseline and periodic chest X-ray / CT and pulmonary function tests when starting known pneumotoxic drugs (e.g., amiodarone, bleomycin, nitrofurantoin).
- Monitor symptoms closely; early detection improves outcomes.
- Check blood counts and inflammatory markers as indicated.
- Long-term follow-up for those with fibrosis or persistent impairment.
Patient counselling points (what to tell patients)
- Tell your doctor if you develop new cough, shortness of breath, fever, chest pain or blood in sputum after starting any medicine.
- Bring a list of all medicines (including OTC and herbal) to each visit.
- Do not stop prescribed heart or cancer medicines without discussing with your doctor — balance risks and benefits.
- If advised to stop a drug, follow up for repeat tests and specialist review as needed.
Detailed Notes:
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