Safety profile of quinolones

Tolerability data from reports to Federal Drug Authorities, information from drug companies, medical literature, and personal experience are cited. Tolerability data regarding norfloxacin were derived from more than 31,000 patients in a phase IV study; ofloxacin from more than 14,000 patients in a phase IV study; and ciprofloxacin from more than 8,000 patients during phase II and phase III studies. Adverse experiences occurred in 6.8% of patients treated with norfloxacin, 9.1% with ciprofloxacin, and 9.3% with ofloxacin. The most frequent adverse effects involved the gastrointestinal tract. Untoward effects were generally mild and reversible when therapy was discontinued.