Oral fluoroquinolones and risk of fibromyalgia.

The Food and Drug Administration (FDA) has recently included a black box warning on fibromyalgia-like symptoms with fluoroquinolones (FQs) but no large epidemiologic study is to date available. We undertook a case-control study using a random sample of 9 053 240 subjects obtained from the PharMetrics Plus health claims database in the United States. Cases received at least two fibromyalgia diagnoses coded by a rheumatologist matched to ten randomly selected controls. After identifying 5148 cases of fibromyalgia and 51 480 controls, the adjusted rate ratio (RR) of fibromyalgia for use of any fluoroquinolones, amoxicillin and azithromycin were 1.63 (95% CI: 1.41-1.87), 1.64 (95% CI: 1.46-1.85) and 1.68 (95% CI, 1.49-1.89), respectively. The adjusted RR for any use of FQ compared to any use of amoxicillin or azithromycin was 0.99 (95% CI: 0.83-1.18) and azithromycin is 0.97 (95%CI: 0.82-1.16), respectively. The risk of fibromyalgia with FQs is similar to that with amoxicillin and azithromycin.