Background: Data have pointed at an impaired fracture healing with fluoroquinolones and
thus potentially a decreased bone biomechanical competence.
Objectives: To study fracture risk associated with antibiotics.
Methods: It is a case control study. There were 124,655 fracture cases and 373,962 age and gender
matched controls. The main exposure was use of various groups of antibiotics. Confounder control was
performed for social variables, contacts to hospitals and general practitioners, alcoholism and a number
of other variables.
Results: An increased risk of any fracture (OR =1.45, 95% CI: 1.42 -1.49), hip (1.46, 95% CI: 1.35-
1.58), forearm (1.67, 95% CI: 1.55 -1.80), and spine fractures (1.38, 95% CI: 1.18-1.60) was seen with
the use of dicloxacillin and flucloxacillin. There was a dose response relationship for overall risk of
fractures, hip, and forearm fractures but not for spine fractures with dicloxacillin and flucloxacillin.
None of the other groups of antibiotics against bacteria, tuberculosis, virus, and fungi were
systematically associated with any major change in the risk of fractures.
Conclusion: Dicloxacillin and flucloxacillin seem associated with an increased risk of fractures. The
cause for this increase has to be determined but may be related to their use against infections of the
bone, the increase thus rather being due to the underlying disease than the drug. Other types of
antibiotics especially the fluoroquinolones were not systematically associated with an increased risk of