Clinical Effects:

  • USES: Fluoroquinolones are bacteriocidal broad spectrum antibiotics. PHARMACOLOGY: Fluoroquinolones inhibit bacterial topoisomerase IV and DNA gyrase enzymes required for DNA replication, transcription, repair and recombination. EPIDEMIOLOGY: Overdose is rare. OVERDOSE: Dizziness, drowsiness, disorientation, slurred speech, nausea and vomiting. ADVERSE EFFECTS: Nausea/vomiting, diarrhea, headache, drowsiness, and insomnia. Seizures, hallucinations, elevated liver enzymes and renal toxicity are rare. Seizures appear related to predisposing factors. Hypersensitivity reactions including anaphylaxis and vasculitis have developed. WITHDRAWAL FROM MARKET: Grepafloxacin was withdrawn from the worldwide market in October, 1999 after reports of cardiovascular toxicity; QT prolongation had been associated with its use. Gatifloxacin was voluntarily withdrawn from the market in May 2006 due to reports of severe hypo- and hyperglycemic events.

Range of Toxicity:

  • Unknown. Recommended dose (adults): 300-500 mg BID; contraindicated in children.


  • Support: Treatment is symptomatic and supportive.
  • Decontamination: Activated charcoal, gastric lavage
  • Seizure: IV benzodiazepines, barbiturates
  • Monitoring of patient: Monitor liver enzymes and renal function with significant overdose. Monitor fluid & electrolyte status if severe GI effects; CNS function.