Nitrofurantoin: friend or foe?

Nitrofurantoin remains the gold standard treatment of uncomplicated cystitis as well as prophylactic treatment of recurrent urinary tract infections. Drug-induced hepatotoxicity presents in acute (3 in 1 000 000) and chronic (1 in 1500) forms. We present a patient with acute liver failure after 5 days of treatment. A 69-year-old man admitted for chronic obstructive pulmonary disease exacerbation 5 days into treatment for cystitis with nitrofurantoin. On admission he was noted to be jaundiced with elevated liver enzymes and normal international normalised ratio. Investigation for infectious, autoimmune and cholestatic causes of hepatotoxicity was negative. The patient improved after discontinuation of the drug and 10 days of methylprednisolone. There are scant data on acute liver failure in the setting of short-term nitrofurantoin administration. The mechanism of toxicity remains unclear, but is hypothesised to be an autoimmune process in which steroids may play a role in treatment. Diagnosis is one of exclusion as the only definitive method of diagnosis is rechallenge. © BMJ Publishing Group Limited 2018. No commercial re-use. See rights and permissions. Published by BMJ.