# Flumazenil: veterinary dose and monograph

> Flumazenil is a veterinary drug. A benzodiazepine-receptor ANTAGONIST — the specific reversal agent for benzodiazepines (diazepam, midazolam, and the zolazepam component of tiletamine-zolazepam/Zoletil). Indications include reversal of benzodiazepine (diazepam/midazolam) over-sedation or paradoxical excitation; reversal of the zolazepam component of tiletamine-zolazepam (Zoletil/Telazol) for rough/prolonged recoveries; benzodiazepine-induced respiratory depression (adjunct to ventilation). This monograph lists 7 reference doses for dogs, cats, cattle, horses, sheep and pigs, each with route, frequency and source, plus meat and milk withdrawal periods for food animals.

Source: https://vetmasterji.com/drugs/flumazenil · Last reviewed: 2026-10-01

## At a glance

- **Drug class:** Veterinary drug
- **Also known as:** Anexate, Romazicon, Flumaz(enil)
- **Species with doses:** Dogs, Cats, Cattle, Horses, Sheep and Pigs
- **General dose range:** 0.01–0.02 mg/kg IV single dose (repeat as needed) — check the species tables for the indication
- **Routes:** IV
- **Last reviewed:** 1 October 2026

## Indications

- Reversal of benzodiazepine (diazepam/midazolam) over-sedation or paradoxical excitation
- Reversal of the zolazepam component of tiletamine-zolazepam (Zoletil/Telazol) for rough/prolonged recoveries
- Benzodiazepine-induced respiratory depression (adjunct to ventilation)
- Hepatic encephalopathy — transient improvement of obtundation (adjunct)

## Flumazenil dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

### Dogs

*Flumazenil doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Benzodiazepine reversal | 0.01–0.02 mg/kg | IV | single dose, repeat as needed | — |
| Hepatic encephalopathy (adjunct) | 0.02 mg/kg | IV | single dose; may repeat if responsive | — |

- Benzodiazepine reversal: Papich 5e: 0.02 mg/kg (20 µg/kg) IV, or 0.2 mg total IV as needed. Plumb’s p.535: 0.01 mg/kg IV (Bunch; Wismer) — may need repeating as the half-life is about 1 h; can be given intratracheally in an emergency. Watch for re-sedation.
- Hepatic encephalopathy (adjunct): Plumb’s p.535: 0.02 mg/kg IV once (Bunch 2003); if the dog responds it is safe to repeat (Michel 2003).

### Cats

*Flumazenil doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Benzodiazepine reversal | 0.01–0.02 mg/kg | IV | single dose, repeat as needed | — |

- Benzodiazepine reversal: Papich 5e: 0.02 mg/kg IV (or 0.2 mg total). Plumb’s p.535 (Wismer 2004): 0.01 mg/kg IV, repeated as needed (half-life about 1 h).

### Cattle

*Flumazenil doses for cattle*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Benzodiazepine reversal | 0.02 mg/kg | IV | single dose, repeat as needed | — | Withdrawal NOT established — treat as extra-label |

- Benzodiazepine reversal: Papich 5e: 20 µg/kg IV. No withdrawal established — obtain FARAD advice.

### Horses

*Flumazenil doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Benzodiazepine reversal | 0.02 mg/kg | IV | single dose, repeat as needed | — |

- Benzodiazepine reversal: Papich 5e (horses, cattle, swine, sheep): 20 µg/kg (0.02 mg/kg) IV.

### Sheep

*Flumazenil doses for sheep*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Benzodiazepine reversal | 0.02 mg/kg | IV | single dose, repeat as needed | — | Withdrawal NOT established — treat as extra-label |

- Benzodiazepine reversal: Papich 5e: 20 µg/kg IV. No withdrawal established — obtain FARAD advice.

### Pigs

*Flumazenil doses for pigs*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Benzodiazepine reversal | 0.02 mg/kg | IV | single dose, repeat as needed | — | Withdrawal NOT established — treat as extra-label |

- Benzodiazepine reversal: Papich 5e: 20 µg/kg IV. No withdrawal established — obtain FARAD advice.

### Buffalo

No buffalo-specific doses are on file, so buffalo are dosed as cattle.

*Flumazenil doses for buffalo*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Benzodiazepine reversal | 0.02 mg/kg | IV | single dose, repeat as needed | — | Withdrawal NOT established — treat as extra-label |

- Benzodiazepine reversal: Papich 5e: 20 µg/kg IV. No withdrawal established — obtain FARAD advice.

## Contraindications

Patients on long-term benzodiazepines for seizure control (reversal can precipitate seizures). Mixed overdoses where a benzodiazepine is protecting against another drug's seizures (e.g. TCA overdose). Known hypersensitivity. Use judiciously — it removes the benzodiazepine's anticonvulsant protection.

## Adverse effects

- Re-sedation when it wears off before the benzodiazepine (short duration)
- Seizures (if reversing in a benzodiazepine-dependent or mixed-overdose patient)
- Agitation/anxiety on abrupt reversal
- Rare arrhythmia

## Drug interactions

- Benzodiazepines (diazepam, midazolam, zolazepam): the drugs it antagonises (intended)
- Pro-convulsant drugs / TCA overdose: reversing benzodiazepine protection can unmask seizures
- Does NOT reverse opioids, alpha-2 agonists, barbiturates, propofol or the dissociative component of tiletamine

## Pregnancy and lactation

Limited data; use when reversal is clinically needed.

## Monitoring

- Level of consciousness / sedation and respiration after reversal
- Re-sedation (it is shorter-acting than most benzodiazepines — watch and re-dose)
- Seizure activity (especially in benzodiazepine-dependent or mixed-overdose patients)

## Toxicity and overdose

Generally well tolerated; the principal risks are SEIZURES (in benzodiazepine-dependent patients or mixed overdoses where the benzodiazepine was suppressing seizures) and RE-SEDATION as it wears off before a longer-acting benzodiazepine. Abrupt reversal can cause agitation. True overdose toxicity is uncommon.

Management: No specific antidote. Supportive — manage seizures with... (re-administering a benzodiazepine is logical if seizures result from reversal) and provide standard seizure/supportive care; monitor for re-sedation and re-dose flumazenil as needed for recurrent benzodiazepine sedation.

## Clinical pearls

- The specific antidote for benzodiazepines — reverses diazepam/midazolam over-sedation and the zolazepam part of Zoletil (smoothing rough recoveries)
- It is SHORT-acting: a single dose may wear off before the benzodiazepine, so watch for re-sedation and re-dose
- Avoid abrupt reversal in benzodiazepine-dependent (chronic seizure) patients or mixed overdoses (e.g. TCA) — you may precipitate seizures
- It does NOT touch opioids, alpha-2 agonists, propofol/barbiturates, or the dissociative (tiletamine/ketamine) component — use the right reversal for the right drug

## Mechanism of action

A competitive antagonist at the benzodiazepine binding site of the GABA-A receptor. It displaces benzodiazepines (and benzodiazepine-like ligands) without activating the receptor itself, abolishing their potentiation of GABA-mediated inhibition — thereby reversing benzodiazepine sedation, respiratory depression and paradoxical excitation. It has little effect in the absence of a benzodiazepine (and does not reverse other sedatives/opioids).

## Formulations and products

- Injection 0.1 mg/mL
- Anexate — 0.1 mg/mL (0.5 mg/5 mL) injection, Injection (human-label)
- Flumazenil — 0.1 mg/mL injection, Injection (human-label)

## Storage

Injection: 15–30 °C, protect from light; do not freeze.

## Before you use this dose

> **Caution:** Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

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## Frequently asked questions

### What is the dose of Flumazenil for dogs?

Reference doses for Flumazenil in dogs: 0.01–0.02 mg/kg IV single dose, repeat as needed (Benzodiazepine reversal); 0.02 mg/kg IV single dose; may repeat if responsive (Hepatic encephalopathy (adjunct)). Confirm against the label and the patient before use.

### What is the dose of Flumazenil for cats?

Reference doses for Flumazenil in cats: 0.01–0.02 mg/kg IV single dose, repeat as needed (Benzodiazepine reversal). Confirm against the label and the patient before use.

### What is the dose of Flumazenil for cattle?

Reference doses for Flumazenil in cattle: 0.02 mg/kg IV single dose, repeat as needed (Benzodiazepine reversal). Confirm against the label and the patient before use.

### What is the withdrawal period for Flumazenil?

Cattle, IV (Benzodiazepine reversal): Withdrawal NOT established — treat as extra-label; Sheep, IV (Benzodiazepine reversal): Withdrawal NOT established — treat as extra-label; Pigs, IV (Benzodiazepine reversal): Withdrawal NOT established — treat as extra-label. Follow the product label and national regulations where they differ.

### When should Flumazenil not be used?

Patients on long-term benzodiazepines for seizure control (reversal can precipitate seizures). Mixed overdoses where a benzodiazepine is protecting against another drug's seizures (e.g. TCA overdose). Known hypersensitivity. Use judiciously — it removes the benzodiazepine's anticonvulsant protection.

### What are the side effects of Flumazenil in animals?

Re-sedation when it wears off before the benzodiazepine (short duration); Seizures (if reversing in a benzodiazepine-dependent or mixed-overdose patient); Agitation/anxiety on abrupt reversal; Rare arrhythmia.

## Sources

- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual, 11th edition
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.