Encephalopathy is a rare side effect of third- and
fourth-generation cephalosporins. Renal failure and
previous disease of the central nervous system predispose to this neurotoxicity. We describe a case of encephalopathy with generalised triphasic waves in a patient with pre-existent cerebrovascular disease who was treated with ceftriaxone for a urinary tract infection. Early recognition of this complication is relevant given that ceftriaxone discontinuation reverted the neurological syndrome.