Drug-induced Interstitial Lung Disease Due to OTC Cold Medicine Taken for 25 Years

Abstract and Introduction

Abstract

Introduction: We report a rare case of drug-induced interstitial lung disease due to over-the-counter cold medicine taken daily for 25 years to clear the patient's head.

Case Presentation: A 77-year-old Japanese man presented to our hospital with a worsening cough that started 5 years ago. Chest radiographs and computed tomography images showed bilateral opacities, and transbronchial lung biopsy specimens showed an organizing pneumonia pattern. He reported taking the same over-the-counter cold medicine daily for the past 25 years to clear his head. We suspected that the cold medicine caused the lung opacities and asked him to stop taking them. His cough, general fatigue, and chest infiltrate gradually diminished. However, 6 months later, he resumed the same treatment because of a cold. The following month, he presented with severe worsening cough and chest radiographical findings. We diagnosed drug-induced interstitial lung disease. He improved by stopping the cold medicine again and taking prednisolone.

Conclusions: Over-the-counter cold medicines are easily accessible at the drugstore. In cases of diffuse lung disease, we should consider drug-induced interstitial lung disease due to over-the-counter cold medicine, which patients have been taking not only for weeks or months but also years.

Introduction

When we catch a cold, we can get an over-the-counter (OTC) cold medicine from any drugstore. The pharmaceutical affairs law in Japan does not require drugstore registered sellers to always ask in detail about symptoms, and they are not obligated to explain the effects and side effects of the medicine. If more cold medicine is required on another occasion or in another store, the drugstore clerk might sell it without checking the patient's medication history. Although the prevalence is low, drug-induced interstitial lung disease cases due to OTC cold medicine are being reported.^[1] The mechanisms through which drug-induced lung disease occurs are likely to involve direct damage to alveolar epithelial or capillary endothelial cells, dysregulation of the immune system, systemic cytokine release, cell-mediated lung damage, and free radical production with oxidative injury.^[2] The drug-induced lymphocyte stimulation test (DLST) is not always positive.^[3] Some OTC cold medicines contain codeine, dihydrocodeine, and caffeine; some patients might continue taking the medicine due to the addictive effects. However, drug-induced interstitial lung disease after long-term use has never been reported. We report an extremely rare case of drug-induced interstitial lung disease due to OTC cold medicine taken every day for 25 years.