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Flumazenil Side Effects

Medically reviewed by Last updated on Jun 10, 2024.

Applies to flumazenil: parenteral injection.

Side effects include:

Dizziness, injection site pain, increased sweating, headache, and abnormal or blurred vision.

For Healthcare Professionals

Applies to flumazenil: intravenous solution.

Nervous system

Very common (10% or more): Dizziness (vertigo, ataxia) (10%)

Common (1% to 10%): Headache, paresthesia (sensation abnormal, hypoesthesia)

Frequency not reported: Convulsions, somnolence, speech disorder (dysphonia, thick tongue)[Ref]

Convulsions have occurred in patients with severe hepatic impairment, inpatients relying on benzodiazepine effects to control seizures, patients physically dependent on benzodiazepines, and those who have ingested large doses of other drugs (mixed-drug overdose).[Ref]


Common (1% to 10%): Agitation (anxiety, nervousness, dry mouth, tremor, palpitations, insomnia, dyspnea, hyperventilation), emotional lability (crying abnormal, depersonalization, euphoria, increased tears, depression, dysphoria, paranoia)

Frequency not reported: Confusion (difficulty concentrating, delirium)

Postmarketing reports: Fear, panic attacks in patients with a history of panic disorders[Ref]


Common (1% to 10%): Cutaneous vasodilation (sweating, flushing, hot flushes)

Uncommon (0.1% to 1%): Cardiac dysrhythmias (ventricular tachycardia, junctional tachycardia)

Frequency not reported: Arrhythmia (atrial, nodal, ventricular extrasystoles), bradycardia, tachycardia, hypertension, chest pain[Ref]


Common (1% to 10%): Fatigue (asthenia, malaise)

Frequency not reported: Death, abnormal hearing (transient hearing impairment, hyperacusis, tinnitus), rigors, shivering

Postmarketing reports: Withdrawal symptoms[Ref]

The majority of deaths occurred in patients with serious underlying disease or in patients who had injects large amounts of non-benzodiazepine drugs (usually cyclic antidepressants) as part of an overdose.

Withdrawal symptoms may occur after rapid injection of flumazenil in patients with long term exposure to benzodiazepines.[Ref]


Common (1% to 10%): Injection site pain, injection site reaction (thrombophlebitis, skin abnormality, rash)[Ref]


Common (1% to 10%): Abnormal vision (visual field defect, diplopia)[Ref]


Frequency not reported: Hiccup[Ref]


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2. Lheureux P, Vrankx M, Askenasi R (1991) "Administration of flumazenil." Ann Emerg Med, 20, p. 592-3

3. Marchant B, Wray R, Leach A, Nama M (1989) "Flumazenil causing convulsions and ventricular tachycardia." BMJ, 299, p. 860

4. Mordel A, Winkler E, Almog S, Tirosh M, Ezra D (1992) "Seizures after flumazenil administration in a case of combined benzodiazepine and tricyclic antidepressant overdose." Crit Care Med, 20, p. 1733-4

5. Thomas P, Lebrun C, Chatel M (1993) "De novo absence status epilepticus as a benzodiazepine withdrawal syndrome." Epilepsia, 34, p. 355-8

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7. Short TG, Galletly DC (1989) "Residual psychomotor effects following reversal of midazolam sedation with flumazenil." Anaesth Intensive Care, 17, p. 290-7

8. (2001) "Product Information. Romazicon (flumazenil)." Roche Laboratories

9. Chern TL, Kwan A (1996) "Flumazenil-induced seizure accompanying benzodiazepine and baclofen intoxication." Am J Emerg Med, 14, p. 231-2

10. (2018) "Product Information. Flumazenil (flumazenil)." Baxter I.V. Systems Division

11. Seebach J, Jost R (1992) "Flumazenil-induced psychotic disorder in hepatic encephalopathy." Lancet, 339, p. 488-9

12. Griffiths RR, Evans SM, Guarino JJ, Roache JD, Furman WR, Liebson I, Schwam EM (1993) "Intravenous flumazenil following acute and repeated exposure to lorazepam in healthy volunteers: antagonism and precipitated withdrawal." J Pharmacol Exp Ther, 265, p. 1163-74

13. Birch BR (1992) "Cardiac arrest associated with flumazenil." BMJ, 305, p. 180-1

14. Katz Y, Boulos M, Singer P, Rosenberg B (1992) "Cardiac arrest associated with flumazenil." BMJ, 304, p. 1415

15. Bodenham AR (1989) "Death after flumazenil." BMJ, 299, p. 457

16. Short TG, Maling T, Galletly DC (1988) "Ventricular arrhythmia precipitated by flumazenil." Br Med J (Clin Res Ed), 296, p. 1070-1

17. Herd B, Clarke F (1991) "Complete heart block after flumazenil." Hum Exp Toxicol, 10, p. 289

18. Lopez A, Rebollo J (1990) "Benzodiazepine withdrawal syndrome after a benzodiazepine antagonist." Crit Care Med, 18, p. 1480-1

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.