A general anaesthetic is used for many different types of operation (surgery) or procedure.

It's done so that during the procedure:

• you're asleep (unconscious)
• you do not feel any pain
• you're not aware of what's happening
• you're not moving and your muscles are relaxed, so doctors can treat you safely

A general anaesthetic is used if other types of anaesthetic are not suitable. These include a local anaesthetic or regional anaesthetic (where you're awake but the part of your body being treated is numbed) or sedation (where you're relaxed but not unconscious).

If you're going to have a general anaesthetic, you'll be given advice about things you can do to prepare.

If your procedure is planned in advance, you can help your recovery and help make your treatment more successful by:

• making sure any long-term conditions are managed as well as possible, such as diabetes, high blood pressure or anaemia
• keeping as physically active as possible, including doing exercise that raises your heart rate if you can
• stopping smoking
• getting treatment for any problems with your teeth, to reduce the risk of them being damaged by the breathing tube that's used during the general anaesthetic

Pre-operative assessment

You'll usually be asked to go to an appointment a few weeks before your procedure (a pre-operative assessment). This is to make sure you're well enough to have the procedure and the general anaesthetic.

It might involve having tests such as blood tests, an X-ray, an electrocardiogram (ECG) to check your heart and a fitness test.

You might also meet the specialist doctor (anaesthetist) who will give you the general anaesthetic when you have your operation or procedure.

Tell the doctor or nurse if:

• you take any medicines
• you have any health conditions
• you've ever had an allergic reaction to a general anaesthetic or any other medicine
• you have any concerns about the procedure, for example, if you have a fear of needles

Before your general anaesthetic

You'll be given advice about what to do in the few days before your general anaesthetic. It's important to follow instructions you're given about:

• when to stop eating and drinking, usually a few hours before the general anaesthetic – this is to make sure your stomach is empty
• whether to keep taking your usual medicines
• washing – you may be given a disinfecting shower gel to use for a few days
• removing jewellery, piercings and nail varnish

A general anaesthetic is given in hospital. The anaesthetic team, led by a specialist doctor (consultant anaesthetist), will monitor you and adjust the anaesthetic when they need to.

You may be given other medicines before the general anaesthetic. This may include medicines to help you relax, reduce stomach acid, stop you feeling sick or help with pain.

The type of general anaesthetic that's used depends on the procedure you're having and what's best for you. It can be given as:

• an injection through a small tube (cannula) into a vein in your arm
• a gas that you breathe in through a mask – this is usually only used if it's difficult to find a vein in your arm

The general anaesthetic starts to work quickly. You'll fall asleep (become unconscious) within about a minute and will not be aware of anything until you wake up after the procedure.

During the procedure an anaesthetist will stay with you all the time. They will:

• monitor your heart rate, blood pressure and oxygen levels
• put a tube into your throat while you're asleep to help you breathe
• give you fluids through a drip into a vein

How long you're asleep (unconscious) depends on the type of procedure you're having. It can be from a few minutes to several hours.

You'll wake up either in the operating theatre after the procedure is over, or in the recovery room.

After a general anaesthetic you'll start to wake up soon after the medicine is stopped at the end of the procedure.

You'll feel drowsy at first. You may have an oxygen mask to help you breathe. This will be removed when you're fully awake. Staff will look after you and give you medicines for any pain or sickness (nausea).

You can usually start eating and drinking again when you feel ready.

The effects of a general anaesthetic can last around 24 hours. How long it takes to fully recover depends on the type of procedure you had.

You may be able to go home within a few hours. Someone will need to collect you from the hospital and take you home by car or taxi.

What to do while you recover

You'll be given advice about what to do and things to avoid for at least 24 hours after having a general anaesthetic.

A general anaesthetic can cause side effects, including:

• feeling thirsty
• feeling drowsy
• a hoarse voice or a sore throat caused by the tube in your throat during the procedure
• shivering
• feeling sick or being sick
• pain, bruising or soreness from the injection or from lying still during the procedure
• feeling confused or memory loss

Side effects will usually get better within a few minutes or hours. You may need medicines to help with side effects, such as pain or sickness.

Ask for an urgent GP appointment or get help from NHS 111 if:

Complications can happen during or after a general anaesthetic, but these are rare. Your doctor will explain the risks to you before the procedure.

Possible complications can include:

• a serious allergic reaction to the anaesthetic
• breathing difficulties
• a chest infection
• damage to your teeth or mouth from the breathing tube
• damage to your eyes
• damage to your nerves, which can cause numbness, tingling or weakness
• longer lasting confusion, particularly in older people

Your care team at the hospital will check for any complications and give you treatment if you need it.

It's very rare to become accidentally aware or conscious during the procedure. The anaesthetist will monitor you carefully to make sure you have the right amount of anaesthetic to keep you asleep.

• Royal College of Anaesthetists: anaesthesia explained
• Royal College of Anaesthetists: preparing for surgery – fitter better sooner
• Royal College of Anaesthetists: anaesthesia and risk