General anaesthesia
- Dr Tharaka Wijerathne, Consultant Anaesthetist
General anaesthesia is when you have medicines to make you sleep and become temporarily unconscious during an operation. The medicines will stop you feeling pain or other sensations while the effect lasts.
About general anaesthesia
The word ‘anaesthesia’ means 'loss of sensation'. Having a general anaesthetic puts you into a controlled state of unconsciousness.
A general anaesthetic is usually several medicines used together to:
- make you unconscious
- stop you feeling pain
- stop you remembering what happened
You may also have medicines to relax your muscles. You’re likely to need these if you’re having an operation on your tummy (abdomen) or chest.
If you have a general anaesthetic, it means you’ll be unconscious all the way through your operation. Your anaesthetist will stay with you throughout your procedure. When your operation is finished, they’ll stop the anaesthetic drugs. You’ll wake up and you won’t remember what happened.
Before your procedure, you’ll meet your anaesthetist or specialist preoperative nurse to discuss your care. It might be different from what we've described here because it will be designed to meet your individual needs.
Preparation for general anaesthesia
Your surgeon and anaesthetist will explain how to prepare for your operation and more about the general anaesthetic, including the potential risks. You might find it helpful to prepare some questions to ask about the procedure or the anaesthetic.
It will help your recovery if you’re as fit and as well as possible beforehand. Here are the main things that can help you to do that.
If you have a long-term health condition such as diabetes or high blood pressure, it can affect how well you recover. It’s a good idea to talk to your GP or nurse about how you can best control your condition.
- If you smoke, try to stop. Smoking makes complications more likely, and it can slow down your healing and recovery.
- Being overweight can increase general anaesthetic risks too. So, it’s a good idea to reach a healthy weight if you need to.
- Follow a healthy lifestyle in the weeks and months before your operation. Be active and eat healthily to help you recover well.
- If you have any damaged crowns or loose teeth, go to the dentist to have these fixed. If your teeth are in good condition, they’re less likely to be damaged during surgery.
You may be sent a patient health questionnaire or a nurse may interview you in advance of you having an anaesthetic. This may be over the phone, by video chat or in person at a pre-op clinic. You may see your anaesthetist at a pre-op clinic, and have some tests and checks done to see what your general health is like. If you regularly take medicines including over-the-counter or herbal medicines, tell the staff at the clinic.
On the day of your operation
A general anaesthetic can sometimes make you sick. If that happens while you’re unconscious, it can be dangerous. So, your stomach needs to be empty before your operation.
Your hospital will give you information about when to stop eating and drinking. You should be able to have some sips of water until just before your operation.
If you’ve been advised to take your usual medicines before your operation, you can take them with a small sip of water.
Follow your anaesthetist or surgeon’s advice and if you have any questions, just ask.
At the hospital
Your nurse or surgeon will talk to you about what will happen, including any pain you might have. If you’re unsure about anything, just ask. No question is too small. Being fully informed will help you feel more at ease and will allow you to give your consent for the procedure to go ahead. You’ll be asked to sign a consent form.
There are some important things to do on the day of your operation.
- Tell your anaesthetist and nurse about any allergies or health conditions you have. It’s important to tell them if you have any difficulties breathing, a pounding heart, dizzy spells, or a recent chest infection. Also tell them about any allergies and reactions to medicines, plasters, or food.
- If you or your family have had a general anaesthetic before and have had any problems during or after it, tell your anaesthetist. That includes being sick afterwards.
- If there’s anything about the anaesthetic or operation that you’re worried about, tell your anaesthetist.
- Tell your anaesthetist about any medicines you’re taking (including herbal remedies) and any you’ve taken that day.
- Tell your anaesthetist if you’ve had any alcohol or taken any drugs because these can affect how anaesthetic medicines work.
- If you smoke, tell your anaesthetist how many cigarettes you smoke a day.
- Take off any make-up and nail varnish. Your skin and lip colour help to tell your anaesthetist that you’re getting enough oxygen. Nail varnish and false nails can interfere with equipment that monitors your oxygen levels.
- Remove jewellery and any piercings. If you cannot remove them, a nurse will put tape over them to prevent damage to them or to your skin.
- If you wear contact lenses, glasses, or hearing aids, remove them when you get to the anaesthetic room.
- Tell your anaesthetist about any loose teeth or crowns and take out any dentures if you have them.
Your anaesthetist will discuss different options with you and explain the risks and benefits of each type of anaesthetic.
Pre-medication
Pre-medication is one or more medicines given to you just before your operation. Not everyone has pre-medication but if you do, your anaesthetist will usually give it to you 30 minutes to two hours before your procedure. Pre-medication can include:
- medicines to reduce the acid in your stomach
- anti-sickness medicines
- painkillers to help you during and after your operation
If you’re very anxious about the operation, you may also have medicines to help you relax.
General anaesthesia procedure
You’ll have your anaesthetic in a room next to the operating theatre or in the operating theatre itself. When you get there, your anaesthetist or operating assistant will go through some safety checks with you. They’ll check your name, ask if you have any allergies and what operation you’re having, for example.
You’ll be connected to equipment that monitors your heart rate, blood pressure, and oxygen levels during the operation. Your anaesthetist may put a sticky strip on your forehead that’s connected to a monitor that records your brain activity while under anaesthesia. You’ll have a small plastic tube called a cannula put into the back of your hand or into your arm.
There are three main ways to have anaesthetic medicines.
- You can breathe them in through a face mask as an anaesthetic gas with oxygen.
- Your anaesthetist can inject them into your vein through the cannula.
- You can have total intravenous anaesthesia (TIVA), where the anaesthetic is delivered via the cannula.
You might have one or a combination of these. Whichever way you have the anaesthetic, it will start to work within a minute or two. You’ll then ‘fall asleep’ and won’t wake up until after your procedure.
When you’re unconscious, your anaesthetist might put a tube in your mouth to help you breathe. They‘ll give you more anaesthetic medicines during the operation to make sure you stay unconscious.
During the operation, your anaesthetist and nurses will make sure you’re warm enough. They’ll also check the position you’re lying in to prevent any damage to your joints, skin, or nerves.
Your anaesthetist may also give you:
- painkillers to prevent pain during and after your procedure
- medicines to relax your muscles so that your surgeon can operate more easily
- antibiotics to prevent infection
- anti-sickness medicines to prevent you from feeling sick afterwards
- medicines to control your blood pressure
- intravenous fluids (a drip) to keep you hydrated
Your anaesthetist will be with you throughout the operation. They’ll watch the monitors and make any changes if needed. At the end of your procedure, they’ll start the process of waking you up by stopping the anaesthetic medicines.
Aftercare following general anaesthesia
When you wake up, you’ll be in a recovery room next to the operating theatre. Your anaesthetist or a specialist nurse will be there to look after you. If you feel sick or have pain, they’ll give you medicines to ease your symptoms.
You may have oxygen to breathe through a mask and fluids through the cannula in your arm. You’ll also be attached to heart, blood pressure, and oxygen monitors for a while after your procedure. You’ll go back to your ward when your anaesthetist is happy that you’re recovering well.
Tell your nurse if you’re in pain. Getting your pain under control will help you to move more, which can help with your recovery.
Other care you have will depend on the type of procedure you’ve had and your personal needs. When your nurse thinks that you’re ready, you can have something to eat or drink.
The effects of the anaesthetic can last for 24 hours or even longer if you’ve had a major operation. When you can go home will depend on the operation you’ve had and how well you’re recovering. If you’ve had a day-case procedure, you’ll usually be able to go home when you’ve recovered and feel ready on the same day. Make sure someone can take you home and stay with you for a day or so while the anaesthetic wears off.
Recovery from general anaesthesia
Having a general anaesthetic can really take it out of you. You might find that you're not so coordinated or that it's difficult to think clearly. This should pass within 24 hours. In the meantime, don’t drive, drink alcohol, operate machinery, or sign anything important.
You may feel tired or even exhausted after a general anaesthetic, and this might last for a few days. If it lasts longer, it’s more likely to be due to other things, such as lack of sleep, anxiety, or not being able to eat or drink properly. The healing process after a big operation can leave you feeling very tired.
Side-effects of general anaesthesia
Side-effects are unwanted but mostly temporary effects of the anaesthetic. They include:
- feeling sick and being sick
- headache
- feeling thirsty
- shivering
- a sore throat
- backache
- bruising
- dizziness
If you’re worried about any side-effects or they don't get better, contact your hospital.
Complications of general anaesthesia
General anaesthetics have some risks. These are different for everyone, so ask your anaesthetist how they apply to you.
Complications are problems that can occur during or after a procedure. General anaesthesia complications are rare but can be serious. They may be more likely if:
- you already have a long-term health condition
- you smoke
- you're overweight
- the surgery is major or being done in an emergency
Some of the main complications of general anaesthesia include the following.
- A severe allergic reaction called anaphylaxis is rare but if it happens, it can be life-threatening. It can cause a rash, itching, difficulty breathing, and low blood pressure. Your anaesthetist will treat you immediately if you have a reaction.
- Nerve damage can happen if you’re in the same position for too long and your nerves get squashed during the operation. It can cause numbness and tingling, pain, warm or cold sensations, and weakness. Symptoms usually get better within a few months but the damage can be permanent.
- Damage to your teeth or mouth can happen. You can get small injuries to your lips, mouth or tongue. Sometimes teeth and crowns can be chipped, broken, or knocked out.
- Being confused or having memory problems can happen after general anaesthesia. You might even develop delirium. This can be caused by many things, including an infection or the side-effects of medicines. It usually gets better with treatment after a few days. Postoperative cognitive dysfunction is when you have trouble with more complicated mental tasks. It can develop over weeks, months or even years. Most people make a full recovery.
Some people worry about being ‘awake’ during an anaesthetic or being aware of what’s going on during the operation. This does happen, but it’s rare. It happens in about one in every 19,000 anaesthetics. It might mean being aware of talking or having something put in your mouth. A few people are aware of being unable to move and feeling pain. It usually lasts for a few minutes, but it can be very distressing. Always tell your anaesthetist after your operation if this has happened to you.
Alternatives to general anaesthesia
General anaesthesia isn’t right for everyone and you may have a regional or local anaesthetic instead.
- Regional anaesthetics completely block pain from a large area of your body. They include spinal and epidural anaesthetics and nerve blocks.
- Local anaesthesia numbs a small area of your body – for example, the area around a tooth that is being taken out.
You’re awake during both of these procedures. You can choose to have a sedative as well to help you relax. How much you remember about the procedure afterwards varies depending on the dose you have. Your anaesthetist will talk to you about the different options and which might be best for you.
Looking for prompt access to quality care?
With our health insurance, if you develop new conditions in the future, you could get the help you need as quickly as possible, from treatment through to aftercare.
To get a quote or to make an enquiry, call us on 0345 609 0111∧
While there are some possible complications of having a general anaesthetic, these are rare so it’s generally safe to have a general anaesthetic. Complications may be more likely if you already have a health condition or you smoke. Being overweight can also increase the risks of general anaesthesia. It’s important to be as fit and well as possible before your operation. Your anaesthetist will discuss risks with you.
For more information, see our section on complications of general anaesthesia.
General anaesthesia makes you unconscious during an operation or procedure and you don’t feel pain or other sensations. Local anaesthesia numbs a small area of your body – for example, around a cut that needs stitches – but you’re awake during the procedure.
For more information, see our section on alternatives to general anaesthesia.
A general anaesthetic is usually a mix of several medicines. These work to:
- stop any pain
- prevent you from remembering what happens during the operation
- make you become unconscious
Your anaesthetist may also give you medicines to relax all your muscles.
You can find out more in our section about general anaesthesia.
You’ll probably have your anaesthetic in a room next to the operating theatre. Your anaesthetist will give you the anaesthetic as an injection or as a gas to breathe. At the end of your procedure, they’ll wake you up by stopping the anaesthetic medicines. Your anaesthetist or a specialist nurse will be there throughout to look after you.
For more information, see our section on general anaesthesia procedure.
The effects of having a general anaesthetic can last for around 24 hours or even longer if you’ve had a major operation. You may feel tired or sometimes exhausted afterwards, and this might last for a few days. The healing process after a big operation can also leave you feeling very tired.
For more information, see our section on recovery from general anaesthesia.
A general anaesthetic is injected into a vein through a thin plastic tube called a cannula. This is usually in the back of your hand or in your arm. But there are two main ways to have anaesthetic medicines. You may also breathe in the anaesthetic through a face mask as a gas mixed with oxygen.
For more information, see our section on general anaesthesia procedure.
Local anaesthesia
Local anaesthesia involves numbing a small part of your body with a medicine called a local anaesthetic to stop pain during and after surgery.
Epidurals for surgery and pain relief
An epidural is an injection of a local anaesthetic and/or other pain-relieving medicine into a space that surrounds your spinal cord
Did our General anaesthesia information help you?
We’d love to hear what you think.∧ Our short survey takes just a few minutes to complete and helps us to keep improving our health information.
∧ The health information on this page is intended for informational purposes only. We do not endorse any commercial products, or include Bupa's fees for treatments and/or services. For more information about prices visit: www.bupa.co.uk/health/payg
This information was published by Bupa's Health Content Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals and deemed accurate on the date of review. Photos are only for illustrative purposes and do not reflect every presentation of a condition.
Any information about a treatment or procedure is generic, and does not necessarily describe that treatment or procedure as delivered by Bupa or its associated providers.
The information contained on this page and in any third party websites referred to on this page is not intended nor implied to be a substitute for professional medical advice nor is it intended to be for medical diagnosis or treatment. Third party websites are not owned or controlled by Bupa and any individual may be able to access and post messages on them. Bupa is not responsible for the content or availability of these third party websites. We do not accept advertising on this page.
- Important complications of anaesthesia. Patient. patient.info, last updated 14 February 2024
- Smith G, D'Cruz JR, Rondeau B, et al. General anesthesia for surgeons. StatPearls Publishing. www.ncbi.nlm.nih.gov/books, last updated 5 August 2023
- You and your anaesthetic. Royal College of Anaesthetists. www.rcoa.ac.uk, reviewed April 2023
- Anaesthesia explained. Royal College of Anaesthetists. www.rcoa.ac.uk, published 1 March 2021
- General anaesthesia. Patient. patient.info, last updated 15 August 2023
- Bayable SD, Amberbir WD, Fetene MB. Delayed awakening and its associated factor following general anesthesia service, 2022: A cross-sectional study. Ann Med Surg 2023; 85(9):4321–8. doi: 10.1097/MS9.0000000000001103
- Your anaesthetic for heart surgery. Royal College of Anaesthetists. www.rcoa.ac.uk, reviewed September 2023
- Preparing for surgery – fitter better sooner. Royal College of Anaesthetists. www.rcoa.ac.uk, accessed 23 May 2024
- Smoking and surgery. Action on Smoking and Health. ash.org.uk, published April 2023
- Patient FAQs. Royal College of Anaesthetists. www.rcoa.ac.uk, published 12 June 2019
- Pre-medication and peri-operative drugs. NICE British National Formulary. bnf.nice.org.uk, published 1 May 2024
- Uitenbosch G, Sng D, Carvalho HN, et al. Expert multinational consensus statement for total intravenous anaesthesia (TIVA) using the Delphi method. J Clin Med 2022; 11(12):3486. doi: 10.3390/jcm11123486
- Chapter 2: Guidelines for the provision of anaesthesia services for the perioperative care of elective and urgent care patients, 2024. Royal College of Anaesthetists. www.rcoa.ac.uk, published 31 January 2023
- Caring for someone recovering from a general anaesthetic or sedation. Royal College of Anaesthetists. www.rcoa.ac.uk, reviewed November 2021
- Common events and risks in anaesthesia. Royal College of Anaesthetists. www.rcoa.ac.uk, published September 2019
- Propofol. NICE British National Formulary. bnf.nice.org.uk, published 1 May 2024
- Risks associated with your anaesthetic. Section 6: Postoperative chest infection. Royal College of Anaesthetists. www.rcoa.ac.uk, published 2017
- Anaesthesia and your weight. Royal College of Anaesthetists. www.rcoa.ac.uk, published February 2020
- Nerve damage after epidural injection. Patient. patient.info, last updated 31 October 2022
- Risks associated with your anaesthetic. Section 11: Nerve damage associated with an operation under general anaesthetic. Royal College of Anaesthetists. www.rcoa.ac.uk, revised 2019
- Your airway and breathing during anaesthesia. Royal College of Anaesthetists. www.rcoa.ac.uk, published February 2020
- Jin Z, Hu J, Ma D. Postoperative delirium: Perioperative assessment, risk reduction, and management. Open Archive 2020; 125(4):492–504. doi: 10.1016/j.bja.2020.06.063
- Brodier EA, Cibelli M. Postoperative cognitive dysfunction in clinical practice. Open Archive 2020; 21(2):75–82. doi: 10.1016/j.bjae.2020.10.004
- Zhao Q, Wan H, Pan H, et al. Postoperative cognitive dysfunction—current research progress. Front Behav Neurosci 2024; 18:1328790. doi: 10.3389/fnbeh.2024.1328790
- Sadiq F, Bauerle J. Awareness under anesthesia. Mo Med 2023; 120(6):459–63 www.ncbi.nlm.nih.gov.
- Guidelines. The ‘nap5 handbook’ concise practice guidance on the prevention and management of accidental awareness during general anaesthesia. Royal College of Anaesthetists. anaesthetists.org, published March 2019
- Rachael Mayfield-Blake, Freelance Health Editor
