Late-onset acetaminophen-induced allergic hepatitis with progression to chronicity.

Acetaminophen (paracetamol), a widely used antipyretic/analgesic, is a well-known agent causing acute hepatic injury. Whereas most cases are caused by its intrinsic hepatotoxicity, idiosyncratic hepatitis by the allergic mechanism is extremely rare. We herein report a case of late-onset acetaminophen-induced allergic hepatitis with progression to chronicity. This unique case extends the spectrum of acetaminophen-induced liver injury. Clinicians should be aware of this unusual clinical manifestation. The mechanism underlying the immunological reaction to acetaminophen remains to be elucidated.