While many anecdotal case reports have described the development of convulsions during treatment with fluoroquinolone antibiotics with or without nonsteroidal anti-inflammatory drugs (NSAIDs), whether signals of convulsion-inducing effects may be detected in a spontaneously reporting adverse event database remains unknown. The aim of the present study was to analyze the adverse events of convulsion for 11 fluoroquinolone antibiotics using the Japanese Adverse Drug Event Report (JADER) database. Our analysis showed that reporting odds ratios (RORs) of convulsion calculated for patients receiving ofloxacin, moxifloxacin, levofloxacin, ciprofloxacin or pazufloxacin without NSAIDs were significantly (the lower limits of 95％CI>1.0)) elevated. In addition, RORs calculated for patients receiving levofloxacin or garenoxacin concomitantly with NSAID were significantly elevated. RORs of convulsion for patients receiving levofloxacin without NSAIDs were significantly elevated only in elderly patients (60 to 79 and ≥80 years), while RORs for patients receiving levofloxacin with NSAIDs were significantly elevated not only in elderly patients (60 to 79 and ≥80 years) but also in younger adults (20 to 59 years). In conclusion, various fluoroquinolone antibiotics may have different convulsion-inducing effects and susceptibility to potentiation by NSAIDs. The effect of aging on the convulsion-inducing potential of levofloxacin may differ in the presence or absence of NSAIDs. Further studies using other adverse drug event databases compiled in different populations are required to confirm the present findings.