What is a general anaesthetic?

A general anaesthetic uses medicines to make you unconscious so you will not feel pain, move or be aware during surgery.

The doctor who manages your general anaesthetic is called an anaesthetist.

Why might I need a general anaesthetic?

General anaesthetics are used for major and some minor operations. Some operations can only be performed under general anaesthetic.

Alternatives to a general anaesthetic include:

• local anaesthetic, which numbs a small area of your body
• regional anaesthetic, which numbs a whole area of your body
• sedation, which makes you sleepy

The best anaesthetic for you depends on the type of surgery you are having, your health and your and your doctors' preferences. You can discuss this with your doctor or anaesthetist before surgery.

Sometimes, children have a general anaesthetic to help them keep still for a procedure, such as an MRI.

How do I prepare for a general anaesthetic?

Before surgery

You will need to fast before you have a general anaesthetic. This is so you do not vomit up food from your stomach and inhale it into your lungs (known as aspiration), which can cause serious complications. A member of your health team will let you know when you need to start fasting.

They may also advise you:

• what medicines you should not take before and on the day of surgery
• not to drink alcohol from the day before surgery
• to quit smoking as early as possible before surgery
• not to use drugs for at least a week before surgery

Meeting your anaesthetist

You will usually meet with your anaesthetist before the surgery. In some cases, you will meet with your anaesthetist a few days before your surgery, especially if you are having major surgery or have any health concerns. In most cases, it will be in the hours before surgery.

Your anaesthetist will ask you about your health and if you or your family have had any problems with anaesthetics in the past. They may also ask about the medicines you take, whether you have allergies and whether or not you smoke.

They might examine your mouth, teeth and veins, and they may listen to your heart and lungs.

Your anaesthetist will explain the type of anaesthetic you will have and what could possibly go wrong. They may ask you to sign a consent form. The form says you agree to the anaesthetic and understand why you are having it and the risks involved.

Your anaesthetist may arrange tests to prepare you for surgery.

You should discuss any questions or concerns with your anaesthetist.

How is a general anaesthetic given?

In most cases, you will receive the general anaesthetic as an injection into a vein on the back of your hand, through a thin plastic tube called a cannula. Sometimes, you will inhale (breathe in) an anaesthetic gas through a mask.

During surgery, your anaesthetist will monitor your level of consciousness, breathing, oxygen level, heart rate and blood pressure. They will usually place a breathing tube in your mouth and give you oxygen.

They will continue giving you anaesthetic medicines through your vein or through a mask to keep you unconscious. Your anaesthetist can adjust the amount of anaesthetic you receive based on what you need at the time.

What happens once I wake up from a general anaesthetic?

When you wake from a general anaesthetic, you might feel sleepy or nauseous, or have a headache. You will usually be in the recovery room when you wake up. A nurse will monitor you. You can ask for medicines to reduce nausea or pain.

If you are staying in hospital, you will be transferred to a ward once you are fully awake.

You can go home after day surgery when you are:

• fully conscious, alert and mobile
• able to manage any side effects, such as nausea or pain
• experiencing only minimal bleeding from your surgical wound
• drinking fluids
• able to urinate (wee)

You can't drive home yourself after a general anaesthetic. You should arrange for someone to pick you up or help you get home. It's best to have someone with you for the next 24 hours so they can make sure you are OK.

What are the side effects of a general anaesthetic?

Common side effects include:

• nausea and vomiting
• dizziness or headache
• tiredness
• itching
• shivering
• blurred vision
• sore throat or dry lips

Older people may experience confusion and memory loss.

What are the risks of a general anaesthetic?

General anaesthetics are generally safe. Some possible risks include:

• damage to your teeth (due to the breathing tube)
• allergic reactions to anaesthetic medicines
• temporary numbness or paralysis
• aspiration (breathing in saliva or your stomach contents)
• chest infection

Although very rare, there is a chance of severe complications. These may include loss of sight, stroke or brain damage, or even death.

Some people are frightened that they might be aware during the operation or feel pain. This is rare. Your anaesthetist will monitor you throughout the operation to make sure that this is very unlikely to happen.

If you are worried about risks and side effects, talk to your anaesthetist before surgery.

Resources and support

• Australian Society of Anaesthetists provides answers to common fears about general anaesthetics.
• The Royal Children's Hospital Melbourne has information about how to prepare your child for general anaesthesia
• The Australian and New Zealand College of Anaesthetists (ANZCA) have a short video on preparing for your operation
• Queensland Health has created a patient information sheet outlining preparation, risks, what to expect and aftercare.

Do you prefer to read in languages other than English?

• Health Translations Victoria has links to a patient's guide to anaesthesia and preparing for day surgery in a range of community languages.