Cefazolin-induced hypoprothrombinemia.

Long-term antibiotic use can be associated with a myriad of side effects, ranging from relatively benign to life-threatening. The most common side effects of cephalosporins include dermatologic reactions and diarrhea. Here, we present a rarer side effect: a spontaneous retroperitoneal hematoma in the setting of cefazolin administration for vertebral osteomyelitis. Several cephalosporins have been implicated in coagulopathy secondary to hypoprothrombinemia. However, only a few case reports have implicated cefazolin, and all have occurred in the context of acute or chronic renal failure. Our case of cefazolin-induced coagulopathy occurred in a patient with normal renal function.