Synopsis
Identify medicine-related pulmonary injury through a precise exposure timeline, stop dangerous triggers safely and exclude infection, cancer, oedema and underlying disease progression.
- Drug-induced lung disease is a causal diagnosis built from phenotype, timing, exclusion of alternatives and response to withdrawal; there is no universal confirmatory test.
- Pulmonary toxicity may appear within hours or only after years, and can worsen after stopping a medicine with a long tissue half-life.
- Obtain all prescription, hospital, oncology, infusion, over-the-counter, herbal and recreational exposures with start, dose-change and stop dates.
Key red flags
Fever, cough, dyspnoea, hypoxaemia, diffuse opacity and sometimes eosinophilia begin soon after exposure, as can occur with acute nitrofurantoin or daptomycin reactions.
Investigation priorities
Identify plausible agents, latency, cumulative exposure and rechallenge.
Management branches
New respiratory symptoms or imaging abnormalities occur during or after a potentially pneumotoxic medicine.
- Assess severity and withhold the suspected medicine if clinically safe, seeking immediate prescribing-specialty advice when withdrawal could destabilise arrhythmia, cancer or another serious disease.
- Build a dated exposure table and define the respiratory phenotype with HRCT, physiology and laboratory tests rather than matching one drug to one image.
Key medicines
Withdrawal of nitrofurantoinNo taper is required: MHRA advises immediate discontinuation if new or worsening symptoms of pulmonary damage occur, with prompt clinical investigation and an alternative antimicrobial plan where infection treatment remains necessary.
Prednisolone for selected inflammatory toxicityThere is no cross-drug regimen; an experienced respiratory, oncology or prescribing specialist selects the daily dose and taper from reaction grade, agent SmPC, infection assessment and local protocol.