Pneumonitis Caused by Metronidazole

The document discusses a case of pneumonitis caused by metronidazole, a drug that has been considered safe over the past 20 years. A 42-year-old woman experienced symptoms such as fever, cough, conjunctivitis, and a maculopapular rash after taking metronidazole for vaginitis. Her symptoms recurred upon rechallenge with the drug, and both episodes resolved after discontinuation of metronidazole. Laboratory tests and chest roentgenograms supported the diagnosis of pneumonitis. This case suggests that metronidazole can cause drug-induced lung disease, which had not been widely reported before. The document also briefly mentions that up to 50% of hospital admissions may be due to adverse drug reactions, and up to 18% of hospitalized patients may suffer from drug side effects, some of which can be fatal.