Also called methohexitone
Methohexital
A fast-acting barbiturate given by injection to start (induce) general anaesthesia, often used during electroconvulsive therapy.
What is Methohexital?
Methohexital, also called methohexitone, is a short-acting barbiturate used to send people quickly to sleep at the start of an anaesthetic, and is often used during electroconvulsive therapy. It is given as an injection into a vein and acts within seconds. The most important thing to understand is that it strongly depresses breathing and the circulation, so it is only ever given by an anaesthetist with full equipment to support the airway and monitor the heart. It is a controlled drug, used only in hospital settings.
Education and reference only. This is a plain-language guide to Methohexital — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Methohexital, historically called methohexitone, is a short-acting barbiturate used in hospital to induce general anaesthesia, meaning it sends a person to sleep quickly at the start of an operation or procedure. One of its common roles is during electroconvulsive therapy, where a brief anaesthetic is needed. It is given as an injection into a vein and works within seconds. Because of how powerfully it affects breathing and the heart, it is used only by anaesthetists in a fully equipped, monitored setting. It is a controlled drug.
How it works
Methohexital acts on the brain by boosting the calming chemical messenger GABA, which rapidly reduces brain activity and produces unconsciousness within seconds of being injected. Its effect is short-lived because the medicine quickly moves out of the brain into other body tissues, so people wake up fairly soon afterwards, which is useful for short procedures. This same powerful, fast action on the nervous system is why it also slows breathing and lowers blood pressure, and why it must be given by someone trained to manage these effects.
Company & origin
Originated / developed by: Specialist manufacturer.
A short-acting barbiturate used in UK hospitals to send people to sleep for anaesthesia, including during electroconvulsive therapy.
Practical use
How to take Methohexital
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given as an injection into a vein by an anaesthetist; you do not take it yourself.
- It is used only in hospital, with equipment to support breathing and monitor the heart.
- Tell the anaesthetic team about all your medicines, allergies and any history of porphyria before it is used.
- Arrange for someone to take you home and stay with you afterwards, as you will be drowsy.
- Do not drive, operate machinery or make important decisions for the rest of the day after having it.
Weighing it up
Advantages & disadvantages of Methohexital
Advantages
- Works within seconds to send a person to sleep at the start of anaesthesia.
- Wears off fairly quickly, which suits short procedures such as electroconvulsive therapy.
- A long-established anaesthetic with well-understood handling by anaesthetists.
Disadvantages
- Strongly depresses breathing and the circulation, so it needs full anaesthetic support and monitoring.
- Can cause pain on injection, involuntary muscle movements, hiccups or coughing.
- As a barbiturate it is a controlled drug and must not be used in people with porphyria.
Practical use
Good to know
The dominant point with methohexital is safety: it markedly depresses breathing and the circulation, so it is given only by an anaesthetist with equipment to support the airway, oxygen and full monitoring; it is never used outside that setting. It works in seconds and wears off fairly quickly, which suits short procedures such as electroconvulsive therapy. As a barbiturate, it is a controlled drug and is handled strictly. People who have the inherited condition porphyria must not receive it, as barbiturates can trigger a dangerous attack. After the anaesthetic, drowsiness, confusion or unsteadiness can linger for a while, so people are watched as they recover and are advised not to drive or make important decisions for the rest of the day.
Who should not take it / use with caution
- People with the inherited condition porphyria must not receive it, as it can trigger a dangerous attack.
- People who have had a serious allergic reaction to methohexital or other barbiturates should not be given it.
- It is used only by an anaesthetist with full airway and monitoring support, with great care in people with serious heart, breathing or liver problems.
Monitoring
- Continuous monitoring of breathing, oxygen, heart rhythm and blood pressure during anaesthesia.
- Watching breathing and consciousness closely in the recovery period.
- Checking suitability beforehand, including any history of porphyria, allergy or serious organ problems.
Side effects
- Depression of breathing and a fall in blood pressure, which the anaesthetist manages closely.
- Pain or irritation where the injection is given, and sometimes involuntary muscle movements, hiccups or coughing.
- Drowsiness, confusion or unsteadiness as the anaesthetic wears off.
- Rarely, serious allergic reactions or, in people with porphyria, a dangerous attack.
Key interactions
- It adds to the effects of other medicines that cause drowsiness or slow breathing, such as opioids and sedatives.
- Alcohol and other sedating substances increase its depressant effects.
- The anaesthetic team takes all your medicines into account when planning your anaesthetic.
Available as: A powder made up into a solution for injection into a vein, given in hospital.
Answers
Methohexital: frequently asked questions
What is methohexital used for?
It is a short-acting barbiturate used to send people to sleep at the start of general anaesthesia, and is often used to provide anaesthesia during electroconvulsive therapy.
Is it the same as methohexitone?
Yes. Methohexital and methohexitone are two names for the same medicine.
Why is it only given by an anaesthetist?
It strongly depresses breathing and the circulation, so it must be given only by an anaesthetist with equipment to support the airway and monitor the heart.
Why can't people with porphyria have it?
Barbiturates such as methohexital can trigger a dangerous attack of porphyria, so it must not be used in people with this inherited condition.
How will I feel afterwards?
You may feel drowsy, confused or unsteady for a while as it wears off, so you should not drive or make important decisions for the rest of the day.
Authoritative sources
- BNF
- NICE CKS
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