Isoflurane

Pronunciation: eye-so-FLOOR-ane.

Generic name
isoflurane
Brand names
Forane (United States), Aerrane (Canada, Australia, New Zealand, some EU member states), Cedaconda (some EU member states)
Drug class
Volatile halogenated general inhalation anaesthetic
Form
Volatile liquid for inhalation vapour, 100%
Route
Inhalation (via a specifically calibrated vaporiser)
Legal status
Prescription-only; a hospital/surgical-centre-administered inhaled anaesthetic given exclusively by trained anaesthesia personnel -- never dispensed for self-administration.

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: Aerrane (5) · Full directory

What isoflurane is and how it works

Isoflurane is a volatile (vaporised) general anaesthetic gas used to put patients to sleep (induce) and keep them asleep (maintain) during surgery or other procedures. (1) (2)

Isoflurane is never a medicine you take yourself. It is given only by inhalation, through a mask or breathing circuit, by an anaesthetist or other clinician specifically trained in general anaesthesia, using specialised equipment (a vaporiser calibrated for isoflurane) in an operating theatre or procedure room. Isoflurane does not carry a formal FDA "boxed warning," but it is still a genuinely high-risk medicine: in people who are genetically susceptible, it can trigger a rare, life-threatening reaction called malignant hyperthermia, and it also carries real risks of liver injury, breathing and blood-pressure effects, and heart-rhythm changes. Your anaesthesia team asks about your own and your family's anaesthesia history specifically to screen for malignant hyperthermia risk before you are given isoflurane.

Mechanism of action: how isoflurane works

Isoflurane is a halogenated volatile general anaesthetic administered by inhalation. Its precise mechanism, like other volatile anaesthetics, is understood to involve modulation of multiple central nervous system ion channels and receptors (including potentiation of inhibitory GABA-A and glycine receptor signalling) producing dose-dependent unconsciousness, amnesia, and immobility; minimum alveolar concentration (MAC) is used as the standard potency measure and decreases with increasing patient age. (1) (2)

What isoflurane is used for

Induction of general anaesthesia

Used, with specialist vaporiser equipment, to start (induce) general anaesthesia before surgery -- though isoflurane's mild pungency means induction is usually started with a short-acting intravenous agent first rather than by inhaling isoflurane alone from the outset, particularly in infants and children. (1) (2)

Maintenance of general anaesthesia

Used to keep a patient safely unconscious (maintained) throughout the duration of surgery or another procedure, at a concentration adjusted continuously by the anaesthesia team. (1) (2)

Caesarean section anaesthesia

Used at low concentrations (0.5-0.75%) as part of general anaesthesia for caesarean section, a use specifically described as safe at this concentration range in the reviewed UK labelling; adequate data for other obstetric anaesthesia applications have not been developed per the US label. (2) (1)

Before taking isoflurane

Do not take / not appropriate for

  • Isoflurane is contraindicated in anyone with known sensitivity to isoflurane or to other halogenated anaesthetic agents. (all countries) (1) (2)
  • Isoflurane is contraindicated in anyone with known or suspected genetic susceptibility to malignant hyperthermia. (all countries) (1) (2)
  • Isoflurane is contraindicated in anyone with a history of confirmed hepatitis from a halogenated anaesthetic, or unexplained moderate-to-severe liver dysfunction following prior anaesthesia with one. (United States) (1)

Tell your clinician about

  • Any personal or family history of malignant hyperthermia or other serious reactions to general anaesthesia.
  • Any personal or family history of neuromuscular disease, particularly Duchenne muscular dystrophy, which increases the risk of dangerous potassium changes during anaesthesia.
  • Any history of unexplained liver problems after a previous anaesthetic, or any anaesthetic with a halogenated agent within the last 3 months.
  • Any heart rhythm problems, especially a personal or family history of QT prolongation.
  • All other medicines you take, especially other sedatives, opioids, calcium-channel blockers, beta-blockers, or MAO-inhibiting antidepressants.
  • Pregnancy, plans for pregnancy, or breastfeeding.
(1) (2)

How to take isoflurane

  • Isoflurane is given only by inhalation, using a vaporiser specifically calibrated for isoflurane, by an anaesthetist or other clinician trained in general anaesthesia -- it is never self-administered.
  • You will be continuously monitored throughout administration for breathing, blood pressure, heart rhythm, and early signs of malignant hyperthermia.
  • Your anaesthesia team adjusts the inhaled concentration continuously throughout your procedure based on your age, response, and the depth of anaesthesia needed -- there is no fixed public dose.
  • Isoflurane is not usually used as the sole agent to start anaesthesia by inhalation in infants and young children, since it can cause coughing, breath-holding, reduced oxygen levels, increased secretions, and spasm of the vocal cords (laryngospasm) during induction.
(1) (2)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)

Missed dose

Not applicable -- isoflurane is administered only by an anaesthesia clinician during a specific procedure in an equipped facility, not on a take-home dosing schedule.

Overdose

Because isoflurane is given and continuously monitored by trained anaesthesia staff, excessive depth of anaesthesia is recognised and managed immediately by the administering team -- this involves stopping isoflurane administration, ensuring a clear airway, giving assisted or controlled ventilation with pure oxygen, and supporting circulation as needed. (1)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Agitation, particularly around induction of anaesthesia.

What to notice: Agitation, particularly around induction of anaesthesia.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Coughing and breath-holding during induction.

What to notice: Coughing and breath-holding during induction.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Nausea and vomiting during recovery.

What to notice: Nausea and vomiting during recovery.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Shivering or chills after the procedure.

What to notice: Shivering or chills after the procedure.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Spasm of the vocal cords (laryngospasm), particularly in children during induction.

What to notice: Spasm of the vocal cords (laryngospasm), particularly in children during induction.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Serious warnings

Malignant hyperthermia — emergency

Symptoms: A sudden rise in body temperature, low blood oxygen, high carbon dioxide levels, muscle rigidity (including jaw muscle spasm), a fast heart rate that does not respond to deepening anaesthesia, fast breathing, bluish skin colour, irregular heartbeats, low blood volume, and unstable blood pressure.

Action: This is a rare, life-threatening reaction that the anaesthesia team is trained and equipped to recognise and treat immediately -- by stopping isoflurane and any other triggering agents, giving intravenous dantrolene sodium, and providing supportive care. This is exactly why your team asks about your own and your family's anaesthesia history beforehand. (1) (2)

Serious liver injury — high caution

Symptoms: Yellowing of the skin or eyes (jaundice), and, rarely, severe liver failure -- these are monitored for and managed by the clinical team after your procedure, particularly if you have had a halogenated anaesthetic within the last 3 months.

Action: Your care team monitors for signs of liver problems after anaesthesia and will investigate and manage them promptly if they occur; this is a recognised, though uncommon, risk of halogenated anaesthetics including isoflurane. (1) (2)

Dangerous rise in blood potassium (perioperative hyperkalaemia) — emergency

Symptoms: Not directly noticeable to the patient during anaesthesia -- this is a rare complication most relevant to children with an underlying neuromuscular disease such as Duchenne muscular dystrophy, and can lead to dangerous heart rhythm disturbances.

Action: Your anaesthesia team screens for a personal or family history of neuromuscular disease beforehand and monitors closely for this risk, responding immediately with early, aggressive treatment if it occurs. (1) (2)

Heart rhythm changes (QT prolongation) — high caution

Symptoms: An abnormal heart rhythm, rarely including a serious rhythm disturbance called torsade de pointes.

Action: Your anaesthesia team monitors your heart rhythm throughout the procedure and takes extra care if you are known to be at risk of QT prolongation. (1) (2)

Serious allergic reaction (anaphylaxis) — emergency

Symptoms: A sudden drop in blood pressure, rash, difficulty breathing, or cardiovascular collapse.

Action: This is a real, sometimes fatal risk that the administering team is equipped and prepared to treat immediately. (1)

Interactions

  • Opioids and nitrous oxide reduce the amount of isoflurane needed to maintain anaesthesia (they decrease its minimum alveolar concentration, or MAC); combined use can also produce a synergistic drop in blood pressure and breathing rate, which the anaesthesia team manages by adjusting doses. (1)
  • Isoflurane markedly increases (potentiates) the effect of muscle-relaxant drugs used during anaesthesia, so the anaesthesia team reduces the muscle-relaxant dose accordingly. (1) (2)
  • Calcium-channel blocker medicines can lead to marked low blood pressure when combined with isoflurane. (1) (2)
  • Beta-blocker medicines may exaggerate the blood-pressure and heart-effect changes caused by isoflurane. (1) (2)
  • MAO-inhibitor antidepressants may increase the risk of unstable blood pressure and heart rate during surgery; UK guidance recommends stopping non-selective MAO inhibitors 15 days before a planned procedure where possible. (2)
  • Adrenaline (epinephrine) given in higher doses during the procedure can trigger dangerous heart-rhythm disturbances when combined with isoflurane. (1) (2)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

There are no adequate, well-controlled studies of isoflurane in pregnant women. Animal studies have shown some reproductive toxicity at higher exposures, and published studies suggest anaesthetic exposure can affect developing brain cells in animal models. For caesarean section specifically, low-concentration isoflurane (0.5-0.75%) has been described as safe in UK labelling. Any decision to use isoflurane in pregnancy is made by your medical team, weighing the necessity of anaesthesia against these considerations. (1) (2) (3) (4) (5) (6)

Breastfeeding

It is not known whether isoflurane or its breakdown products pass into human breast milk; caution is advised, and this should be discussed with your care team. (1) (2) (3) (4) (5) (6)

Children

Isoflurane is used in children, but is generally not used alone as an inhaled induction agent in infants and young children, since it can cause coughing, breath-holding, reduced oxygen levels, increased secretions, and laryngospasm during induction -- induction is more commonly started with a short-acting intravenous agent instead. There is also a real, animal-study-based concern about anaesthetic exposure and developing brain cells with exposures longer than about 3 hours, most relevant to fetuses in the third trimester through roughly age 3, per the reviewed US label. (1) (2) (3) (4) (5) (6)

Elderly

Older patients generally need a lower inhaled concentration of isoflurane to reach the same depth of anaesthesia, since the concentration needed (MAC) decreases with age; your anaesthesia team adjusts for this. (1) (2) (3) (4) (5) (6)

Hepatic_impairment

A history of unexplained liver problems after a previous halogenated anaesthetic, or exposure to one within the last 3 months, is treated as a real risk factor and, in the US label, a contraindication to unexplained-injury cases -- always disclose your anaesthesia history to your care team. (1) (2) (3) (4) (5) (6)

Renal_impairment

No isoflurane-specific renal-impairment dosing guidance was identified in the sources reviewed for this dossier; your anaesthesia team individualises your anaesthetic plan based on your overall health, including kidney function. (1) (2) (3) (4) (5) (6)

Monitoring

Before starting

  • Personal and family history of malignant hyperthermia or other anaesthesia reactions
  • Personal and family history of neuromuscular disease (e.g. Duchenne muscular dystrophy)
  • History of liver problems after previous anaesthesia, or halogenated-anaesthetic exposure within the last 3 months
  • Heart rhythm history, especially QT prolongation risk
  • Review of other medicines, especially calcium-channel blockers, beta-blockers, and MAO inhibitors

During treatment

  • Continuous monitoring of breathing, oxygen levels, blood pressure, heart rhythm, and body temperature throughout administration.
  • Immediate readiness to recognise and treat malignant hyperthermia, including immediate access to intravenous dantrolene sodium.
  • Monitoring for signs of excessive potassium rise in at-risk paediatric patients.
  • Post-procedure monitoring for signs of liver injury (such as jaundice).
(1) (2)

Storage

Stored by pharmacy and clinical staff at controlled room temperature (15-30degC in the US label; below 30degC in a tightly closed amber glass container per the UK SmPC), away from children -- this is managed entirely by hospital/theatre staff, not by patients.

Professional information

Clinician-facing context only, sourced from the current US FDA FORANE prescribing information and current UK emc Isoflurane 100% SmPC; verify against the current full local label before administration. Isoflurane does not carry a formal FDA boxed warning, but the malignant hyperthermia contraindication and warning should be treated with equivalent clinical seriousness.

United States / United Kingdom

Indication: Induction and maintenance of general anaesthesia

Dose summary: Induction: 1.5-3% inspired concentration, surgical anaesthesia typically achieved in 7-10 minutes. Maintenance: 1.0-2.5% with oxygen/nitrous oxide, or an additional 0.5-1% with oxygen alone. Caesarean section: 0.5-0.75%. MAC decreases with increasing age (US label: 1.60% in neonates to 1.05% in patients 55-83 years). Requires a vaporiser specifically calibrated for isoflurane.

Renal context: No isoflurane-specific renal dosing adjustment identified in the sources reviewed for this dossier. (1) (2)

Mechanism of action

Hepatic guidance

A history of confirmed hepatitis attributed to a halogenated anaesthetic, or unexplained moderate-to-severe hepatic dysfunction following prior halogenated-anaesthetic exposure, is a contraindication per the US label; postoperative hepatic dysfunction ranging from mild transient enzyme elevation to rare fatal hepatic necrosis has been reported.

Overdose note

Excessive anaesthetic depth presents as cardiac and/or respiratory depression; manage by stopping isoflurane administration, establishing a clear airway, providing assisted/controlled ventilation with 100% oxygen, and monitoring/supporting cardiovascular function. (1) (2)

Frequently asked questions

Does isoflurane have a boxed warning?

No -- isoflurane's current US FORANE label does not carry a formal FDA boxed warning (confirmed by direct review of both the DailyMed and FDA PDF label forms). However, it is still a genuinely high-risk medicine: it is contraindicated in anyone with known or suspected genetic susceptibility to malignant hyperthermia, a rare but life-threatening reaction, and is only ever given by trained anaesthesia personnel prepared to recognise and treat it immediately. (1)

What is malignant hyperthermia and why does my anaesthesia team ask about it?

Malignant hyperthermia is a rare, life-threatening reaction that isoflurane and other volatile anaesthetics can trigger in genetically susceptible individuals, causing a sudden rise in body temperature, muscle rigidity, and a fast heart rate. Your anaesthesia team asks about your own and your family's history of anaesthesia reactions specifically to screen for this risk beforehand, and they carry intravenous dantrolene sodium and are trained to treat it immediately if it occurs. (1) (2)

Can isoflurane be self-administered at home?

No. Isoflurane is exclusively a hospital/theatre-administered inhaled anaesthetic given by trained anaesthesia personnel using specialised vaporiser equipment. It is never dispensed for self-administration. (1)

What is the mechanism of action of isoflurane?

Isoflurane is a halogenated volatile general anaesthetic administered by inhalation. Its precise mechanism, like other volatile anaesthetics, is understood to involve modulation of multiple central nervous system ion channels and receptors (including potentiation of inhibitory GABA-A and glycine receptor signalling) producing dose-dependent unconsciousness, amnesia, and immobility; minimum alveolar concentration (MAC) is used as the standard potency measure and decreases with increasing patient age. (1) (2)

What is the generic name of Isoflurane?

The generic name is isoflurane. It is sold under brand names including Forane (United States), Aerrane (Canada, Australia, New Zealand, some EU member states), Cedaconda (some EU member states). (1) (2)

What class of drug is isoflurane?

Isoflurane is classed as: Volatile halogenated general inhalation anaesthetic. (1) (2)

References

  1. FORANE (isoflurane, USP) volatile liquid for inhalation -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information · United States · accessed 2026-07-30 · source 1
  2. Isoflurane 100% Inhalation Vapour, Liquid -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom -- Piramal Critical Care Limited · United Kingdom · accessed 2026-07-30 · source 2
  3. Isoflurane -- list of nationally authorised medicinal products (PSUSA/00001786/202211)European Medicines Agency (EMA) -- list of nationally authorised medicinal products (PSUSA procedure) · European Union · accessed 2026-07-30 · source 3
  4. Isoflurane USP (Isoflurane, 99.9%) Inhalation Anesthetic -- Product MonographHealth Canada product monograph · Canada · accessed 2026-07-30 · source 4
  5. AERRANE isoflurane 1 mL/mL inhalation bottle -- ARTG entry 55105Therapeutic Goods Administration (TGA), Australia · Australia · accessed 2026-07-30 · source 5
  6. AERRANE (isoflurane) New Zealand Data SheetMedsafe (New Zealand regulator) · New Zealand · accessed 2026-07-30 · source 6

Brand names by country

Single-ingredient isoflurane names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • Terrell1 mL/mL · piramal critical care, inc.
  • Isoflurane, (Volatile for Inhalation)250 mL/250mL, 100 mL00mL · mullan pharmaceutical inc.
  • FORANE1 mL/mL · baxter healthcare corporation

United Kingdom

  • Isoflurane 100% Inhalation Vapour, Liquid (2)MHRA licensed emc smpc confirmed · 100% · Piramal Critical Care Limited

Canada

  • FORANE

Australia

  • Aerrane (5)TGA ARTG registered 1996-07-17 active · 1 mL/mL (100%) · Baxter Healthcare Pty Ltd

New Zealand

  • Aerrane (6)Medsafe data sheet current 2019-03-04 · 100% · not independently confirmed beyond data-sheet existence in this pass
View brands in additional countries.

European Union

Aerrane / Cedaconda (3)

This page provides general reference information about isoflurane, a hospital/theatre-administered-only general anaesthetic, and is not a substitute for advice from the anaesthesia team managing your care. All administration and dosing decisions are made entirely by trained clinical staff.

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