General anaesthetic for surgery (General anaesthesia)
Medicines, given and managed by an anaesthetist, that put you into a controlled, monitored state of unconsciousness so you feel nothing during an operation.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- A general anaesthetic keeps you fully unconscious and pain-free during surgery, managed throughout by an anaesthetist.
- Modern anaesthesia is very safe, but it is not without risks; common after-effects are usually mild and short-lived.
- You must follow fasting instructions (no food or drink for a set time beforehand) for your safety.
- Tell the anaesthetist about your health, medicines, allergies, smoking and any past anaesthetic problems so they can plan the safest anaesthetic.
- If you take a GLP-1 or GIP weight-loss or diabetes medicine (such as Ozempic, Wegovy, Mounjaro or Saxenda), tell your anaesthetist — including any bought privately — as it can leave food in your stomach despite fasting; do not stop it without advice from your team.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your specialist will give you advice for your situation.
Lets operations be carried out while you are completely unaware and feel no pain
Where a regional, spinal or local anaesthetic would be safer or just as effective, a general anaesthetic may not be the best choice.
You wake in the recovery area with staff beside you, monitoring your breathing, heart rate and pain. You may feel groggy, cold or confused at first.
Continuous monitoring in a recovery area until you are stable, with staff at your side.
You wake in the recovery area with staff beside you, monitoring your breathing, heart rate and pain. You may feel...
Drowsiness, a sore throat, sickness or shivering may settle gradually. You are given pain relief and anti-sickness...
You should not drive, operate machinery, drink alcohol, sign legal documents or be left alone, as your judgement...
Tiredness, mild memory fog or aches usually fade. Most common after-effects have resolved by now.
What is a general anaesthetic for surgery?
A general anaesthetic is a combination of medicines that puts you into a controlled, deep state of unconsciousness so that you are unaware and feel no pain during an operation. It is given and carefully managed by an anaesthetist, a specialist doctor who stays with you throughout.
The medicines are usually given through a thin tube (cannula) in the back of your hand or arm, and sometimes started with anaesthetic gases you breathe in. Once you are asleep, the anaesthetist keeps you at the right depth, looks after your breathing, and monitors your heart, blood pressure, oxygen and other vital signs the whole time. When the operation finishes, the medicines are stopped or reversed and you wake up, usually in a recovery area.
Modern anaesthesia is very safe. Serious problems are rare because of advances in monitoring, medicines and training. But no anaesthetic is completely without risk, and the risk depends on your health and the operation. Honest information helps you weigh it up.
Most people experience some short-lived after-effects, such as a sore throat, feeling sick or feeling drowsy. Serious complications, such as a severe allergic reaction or being aware during the anaesthetic, are rare.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
General compared with regional anaesthetic
| General anaesthetic | Regional / spinal / epidural | |
|---|---|---|
| Awareness | You are fully asleep | You stay awake (or lightly sedated) |
| What it numbs | Your whole body and consciousness | Only the part being operated on |
| Common after-effects | Sore throat, sickness, drowsiness | Numbness/weakness that wears off, headache (spinal/epidural) |
| Suits | Many operations; some must be done asleep | Selected operations, often lower-body |
For some operations only a general anaesthetic is suitable; for others there is a genuine choice. Your anaesthetist will advise what is safest and best for you.
Preparing for your treatment
- Attend your pre-operative assessment so your health is checked and the safest anaesthetic is planned.
- Follow the fasting instructions exactly — you must stop eating and drinking for a set time beforehand, as this protects your lungs while you are asleep.
- Tell the team about all your medicines and which to continue, change or stop, especially blood thinners and diabetes medicines.
- If you take a weight-loss or diabetes injection or tablet known as a GLP-1 or GIP medicine — for example semaglutide (Ozempic, Wegovy, Rybelsus), liraglutide (Saxenda) or tirzepatide (Mounjaro) — tell the anaesthetist beforehand, including any you have bought privately, as these slow stomach emptying and can leave food in your stomach despite fasting. Do not stop them on your own; your team will advise whether to pause or adjust them and may suggest extra precautions.
- Mention any allergies, past problems with anaesthetics, or a family history of anaesthetic reactions.
- Stopping smoking, even for a short time before surgery, can reduce breathing and wound problems.
- Arrange a responsible adult to take you home and stay with you, as you should not drive or be alone straight after.
- Remove make-up, nail varnish and jewellery as asked, and follow instructions about loose dental work.
- Bring your questions; you will usually meet your anaesthetist before the operation to discuss the plan and consent.
What happens
Before your operation you meet the anaesthetist, who reviews your health, explains the plan and answers questions. In the anaesthetic room a cannula is placed in your hand or arm and monitors are attached to track your heart, blood pressure and oxygen.
The anaesthetic medicine is then given, usually through the cannula, and you fall asleep within seconds to a minute. Some people, especially children, breathe gases through a mask instead. Once you are asleep, the anaesthetist supports your breathing, often with a device or tube in your airway, and keeps you at the right depth for the whole operation.
You are monitored continuously throughout. The anaesthetist also gives pain-relief and anti-sickness medicines so you are more comfortable when you wake.
When the operation finishes, the anaesthetic is stopped or reversed and you wake up, usually in a recovery area where staff stay with you until you are stable. You may feel groggy, cold or a little confused at first; this settles as the medicines wear off.
Is this treatment right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- Where a regional, spinal or local anaesthetic would be safer or just as effective, a general anaesthetic may not be the best choice.
- People with certain serious heart, lung or other conditions may need their anaesthetic carefully tailored, or surgery reconsidered.
- A rare inherited reaction to anaesthetic medicines (malignant hyperthermia) or a known severe allergy changes which medicines can be used.
- If you have not fasted as instructed, a planned general anaesthetic is usually delayed for safety.
Delay or rearrange if…
- You have a current chest infection, cold or other acute illness.
- A long-term condition such as diabetes, asthma, heart failure or high blood pressure is poorly controlled.
- You have not followed the fasting instructions.
- Important results or medicine information are missing, or you may be pregnant.
Alternatives to discuss
- Spinal or epidural anaesthesia for suitable, often lower-body, operations.
- A regional nerve block, sometimes with sedation, so you avoid being fully asleep.
- Local anaesthetic alone for smaller procedures.
- Reconsidering whether the operation is needed now, or whether a non-surgical option exists.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Comfort, sedation or contrast choices
If local anaesthetic, sedation, contrast or pain relief is used, ask what is planned, why, and what it means afterwards.
Benefits
- Lets operations be carried out while you are completely unaware and feel no pain
- Allows surgery that could not be done while you are awake
- Keeps you still and your muscles relaxed, which some operations need
- Is managed throughout by an anaesthetist who controls your breathing and vital signs
- Includes pain-relief and anti-sickness medicines to ease your recovery
- Is delivered with continuous monitoring, making serious problems rare
Risks & complications
- Sore throat from the breathing device or tube
- Feeling sick or being sick afterwards
- Feeling drowsy, dizzy, shivery or confused for a while
- Bruising or soreness where the cannula was placed
- Headache, aches and pains, or blurred vision that settle
- A dry mouth
- Minor damage to the lips, tongue or teeth, particularly if teeth are fragile or crowned
- A chest infection, more likely in smokers or those with lung problems
- Temporary difficulty passing urine
- Confusion or memory problems for a time, more common in older people
- Becoming aware during the anaesthetic (accidental awareness)
- A serious allergic reaction (anaphylaxis) to one of the medicines
- Damage to nerves causing numbness or weakness, usually temporary but rarely permanent
- Serious breathing, heart or other complications
- Very rarely, serious harm or death directly due to the anaesthetic, especially relevant where there is serious underlying illness
Most after-effects of a general anaesthetic are mild and short-lived. Serious complications are rare and depend a lot on your general health, your age and the operation. The single most important thing you can do is follow the fasting instructions and be completely honest about your medicines, allergies, smoking and any past anaesthetic problems. Ask the anaesthetist what your particular risks are.
Published figures to discuss
The Royal College of Anaesthetists publishes figures for healthy adults having routine surgery, and uses a scale from very common (more than 1 in 10) to very rare (fewer than 1 in 10,000). These are population figures from large studies; your own risk depends on your health, age and operation, and can be higher if you are seriously unwell. The figures below are drawn cautiously from RCoA patient information and should be treated as approximate.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Sore throat and feeling sick | Very common — more than 1 in 10 people | Usually mild and short-lived; anti-sickness medicine helps and a sore throat settles within a day or two. | MHRA — GLP-1/GIP medicines: aspiration risk during general anaesthesia or deep sedationgov.ukPublished figure |
| Serious allergic reaction (anaphylaxis) | Rare — RCoA patient materials describe figures around 1 in 10,000 | Most people treated promptly recover fully; the anaesthetist is equipped to manage it immediately. | RCoA — Risks associated with general anaesthesiarcoa.ac.ukPublished figure |
| Accidental awareness during anaesthesia | Rare — RCoA describes this as roughly 1 in 19,000 overall in a large UK audit | Far less likely in routine practice with modern monitoring; discuss if you have concerns. | RCoA — Risks associated with general anaesthesiarcoa.ac.ukPublished figure |
| Death directly due to the anaesthetic in a healthy adult | Very rare — far fewer than 1 in 100,000 | Risk rises with serious underlying illness and the size of the operation, so this is highly individual. | MHRA — GLP-1/GIP medicines: aspiration risk during general anaesthesia or deep sedationgov.ukPublished figure |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
There is no wound from the anaesthetic itself, but the medicines take time to clear. Most people feel back to normal within a day or two, though tiredness and mild after-effects can linger a little longer. Your physical recovery is mainly driven by the operation.
- Feeling groggy, cold or a little confused as you wake
- A sore throat for a day or two
- Feeling sick, which usually settles with medicine
- Tiredness for a day or so
- Mild memory fog or difficulty concentrating that improves
Aftercare
- Have a responsible adult take you home and stay with you for the first 24 hours.
- Do not drive, operate machinery, drink alcohol or sign important documents for at least 24 hours, or longer if advised.
- Take pain relief and anti-sickness medicine as directed, and start with light food and fluids.
- Rest, and build activity back up gradually as the operation allows.
- Follow any wound, medicine and follow-up instructions for the operation itself.
- Suck a lozenge or sip fluids to ease a sore throat.
- Contact the team if sickness, drowsiness or confusion is severe or not settling.
- A responsible adult to collect you and stay overnight
- No plans to drive, work or travel alone for 24 hours
- Pain relief and anti-sickness medicine to hand
- Light food and fluids at home
- Clear instructions for the operation's own aftercare
- The clinic or ward contact number saved
- Time off arranged based on the operation, not just the anaesthetic
⚠ Get urgent help if…
- Difficulty breathing, wheezing, or swelling of the face, lips or tongue (possible allergic reaction) — call 999
- Severe or persistent vomiting that stops you keeping fluids down
- Chest pain or a fast, irregular heartbeat
- Confusion or drowsiness that is getting worse rather than better
- A high temperature, productive cough or worsening breathlessness (possible chest infection)
- New numbness, weakness or loss of movement in a limb
- Any warning sign related to your operation, such as heavy bleeding or a hot, swollen, painful calf
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your specialist gives you.
Results & realistic expectations
A good anaesthetic is one you barely remember: you are unaware during surgery, comfortable as you wake, and free of major after-effects. Anti-sickness and pain-relief medicines are used to make waking up as smooth as possible.
A general anaesthetic enables the operation but does not change its result. How well you do overall depends on the surgery, your health and your recovery, not the anaesthetic alone. The anaesthetist's job is to keep you safe and comfortable through the operation and the early recovery.
The effects of a general anaesthetic are temporary and wear off as the medicines clear, usually within hours to a day or two. Most people have no lasting effects. Older people, or those who are frail or seriously unwell, can occasionally have confusion that takes longer to settle; this should be discussed with the team if it happens.
Related tests, treatments or support
A general anaesthetic is often combined with other techniques, such as a nerve block, spinal or epidural, to improve pain relief and reduce how much general anaesthetic is needed. Local anaesthetic may also be used at the wound. Your anaesthetist will explain any combined plan and why it suits you.
Follow-up & long-term care
Most people need no specific anaesthetic follow-up, as after-effects settle quickly. Your follow-up is usually about the operation itself. If you had an unexpected problem, such as a reaction to a medicine or difficulty during the anaesthetic, the anaesthetist should explain it and give you written information so future anaesthetists know.
Repeat, follow-on and what comes next
- The anaesthetic plan made in clinic may be adjusted on the day by the anaesthetist looking after you.
- Occasionally the airway or anaesthetic technique has to be changed during the operation for safety.
- If you had a problem such as a drug reaction, you should be given written details so future anaesthetics can avoid it.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- Continuous monitoring in a recovery area until you are stable, with staff at your side.
- Active prevention and treatment of sickness and pain as you wake.
- Clear written instructions, including the 24-hour driving, alcohol and decision-making advice.
- A named contact if after-effects are severe or not settling.
- Written documentation of any reaction or difficulty for future anaesthetists.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- The anaesthetist's fee, which usually reflects the length and complexity of the operation
- The type of anaesthetic and monitoring needed for your health and the surgery
- Whether extra techniques, such as a nerve block or epidural, are added for pain relief
- Recovery and any high-dependency monitoring after major surgery
- Your overall health, which can affect the anaesthetic plan and monitoring required
- Whether the anaesthetist's fee is included in your overall surgical package or charged separately
- Who your anaesthetist will be and how to contact them with questions
- Whether pain relief, anti-sickness medicine and recovery monitoring are included
- Whether any added technique, such as a nerve block, is included
- What happens, clinically and financially, if extra monitoring or a longer recovery is needed
On the NHS? A general anaesthetic is standard NHS care for operations that need it, and is also used in private surgery; it is part of the cost of the operation rather than a separate self-pay treatment.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Calling a general anaesthetic risk-free rather than very safe but not without risks.
- Not discussing whether a regional, spinal or local option could be used instead or alongside.
- Not explaining common after-effects, fasting rules and the 24-hour driving and alcohol restriction.
- Not asking about past anaesthetic problems, allergies or family reactions to anaesthetics.
- Not giving written information after an unexpected reaction or difficulty.
Marketing red flags
- Describing anaesthesia as risk-free or without risks.
- Glossing over fasting and the need for a responsible adult and no driving for 24 hours.
- Not naming who the anaesthetist is or how to raise concerns.
- Downplaying that risk is higher for people who are seriously unwell.
Choosing a specialist safely
- Check the specialist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good specialist will welcome every one of these.
- What are my particular risks given my health and this operation?
- Could a spinal, epidural or nerve block be used instead of, or alongside, a general anaesthetic?
- What will you do to prevent sickness and control my pain afterwards?
- When exactly should I stop eating and drinking, and which medicines do I take on the day?
- How will my breathing and airway be managed while I am asleep?
- Who looks after me as I wake up, and how long will I be monitored?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the specialist who carries out my treatment, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this treatment not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Will I definitely be asleep and feel nothing?
How safe is a general anaesthetic?
Why can't I eat or drink beforehand?
What are the most common after-effects?
When can I drive or go back to work?
Will it affect my memory?
I take a weight-loss or diabetes injection (like Ozempic, Wegovy or Mounjaro) — do I need to tell the anaesthetist?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: NHS — General anaesthesia RCoA — Risks associated with general anaesthesia RCoA — Anaesthesia and risk (evidence and figures) RCoA — Common events and risks in anaesthesia (infographic) RCoA — Accidental awareness during general anaesthesia RCoA — You and your anaesthetic MHRA — GLP-1/GIP medicines: aspiration risk during general anaesthesia or deep sedation
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
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