Objective: To present a case of a rare pulmonary reaction to carbamazepine.
Clinical features: One month after starting carbamazepine therapy, a previously well 38-year-old man developed pulmonary interstitial pneumonitis associated with debilitating systemic symptoms, the cause of which was not diagnosed for a further three months. Transbronchial lung biopsy showed granulomatous inflammation consistent with an allergic drug reaction.
Intervention and outcome: The patient's clinical status, chest x-ray appearance and arterial blood gas tensions all normalised after withdrawal of the drug without any specific therapy.
Conclusion: Pneumonitis is a rare adverse reaction to carbamazepine therapy. However, awareness may reduce delays in both diagnosis and withdrawal of the drug.