Flumazenil

What is this medication for?

• Reversal of benzodiazepine effects (therapeutic or overdose); adjunct in severe hepatic encephalopathy; zolpidem/imidazopyridine overdose
• Partial reversal of tiletamine-zolazepam anesthesia (shortens recovery; reverses auditory/posture effects, not drowsiness)

How is it given?

This medication is normally given by your veterinary team (in clinic or hospital).

• Never reverse the benzodiazepine that is controlling status epilepticus — you will unleash seizures.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• Injection-site reaction, vomiting, cutaneous vasodilation, vertigo/wobbliness/unsteadiness (Human-reported)

Worth a phone call to your veterinarian

• Any new symptom that worries you.

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Seizures (Chronic benzo users, TCA overdose context (human))

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Hypersensitivity; when benzodiazepines are treating a life-threatening condition (status epilepticus, ↑CSF pressure); serious TCA overdose
• has or has had: Mixed overdoses — extreme caution (reversal can precipitate seizures); may worsen baclofen/carisoprodol toxicity; re-drowsiness after wear-off

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • Long-acting benzodiazepines
  • TCAs

Storage and handling

Room temperature, light-protected. 0.1 mg/mL injection.

Good to know

• Competitive antagonist with a HALF-LIFE SHORTER THAN THE DRUG IT REVERSES — the re-drowsiness trap: patients look great at minute 15 and are comatose again at hour 2. Repeat dosing is the norm, not the exception.
• Never reverse the benzodiazepine that is controlling status epilepticus — you will unleash seizures.
• In severe hepatic encephalopathy, GABA-tone contributes to coma — flumazenil 0.02 mg/kg is a recognized adjunctive wake-up tool (alongside lactulose).
• Useful partial rescue for zolpidem-type hypnotic ingestion (same receptor family).