Abstract
Intravenous zoledronic acid is an established and generally well tolerated form of antiresorptive therapy for osteoporosis. Although mild arthralgias are a well-documented manifestation of the acute phase response to intravenous bisphosphonates, more severe musculoskeletal reactions manifesting as debilitating pain and joint effusions have been rarely documented in the current literature. In this case report, we discuss the case of a 55-year-old woman who developed severe painful bilateral knee effusions within 1 week of her first zoledronic acid infusion for osteoporosis. Prescribing physicians and patients should be made aware of this uncommon but important adverse effect to zoledronic acid.