Histamine H1 antagonist levocetirizine as a potential cause of lung injury

Histamine H1 antagonists rarely cause drug-induced lung injury (DLI). A woman in her 60s, who had been taking antihistaminic levocetirizine for 2 months, presented with progressive cough and shortness of breath. A chest radiograph showed patchy infiltrations on both lower lung fields. Chest computed tomography findings were consistent with non-specific interstitial pneumonia. Serum markers associated with interstitial pneumonias were elevated. Room air arterial blood gas analysis revealed hypoxemia. Restrictive ventilatory impairment was noted with reduced diffusing capacity. Transbronchial lung biopsy specimens demonstrated unclassifiable alveolitis. Steroid pulse therapy was introduced for respiratory distress, but the initial response to treatment was poor. A drug lymphocyte stimulation test was positive for levocetirizine. The interstitial pneumonia improved following withdrawal of levocetirizine. Her illness has not recurred under steroid therapy and the discontinuation of levocetirizine. Antihistaminics may have a potential risk of DLI.