[Pneumonitis induced by rifampicin].

An 86-year-old male with pulmonary tuberculosis developed fever, rash, and interstitial pneumonia 3 weeks after the beginning of treatment with isoniazid (INH), rifampicin (RFP), and ethambutol (EB). Chest CT showed new infiltration shadows that were diffuse bilateral ground-glass opacities mixed with dense consolidation and septal thickening, accompanied by a small amount of pleural effusion. Drug-induced pneumonitis was suspected, and therefore the antituberculous regimen was discontinued. The radiologic findings and symptoms improved promptly. A provocation trial with RFP lead to fever, diarrhea, and rash. Therefore, RFP was considered to be the causative drug. INH and EB were reintroduced without any recurrence of the symptoms. Clinicians should be aware not only of paradoxical reactions but also of drug-induced pneumonitis, when a new pulmonary infiltrate develops in the course of tuberculosis treatment.