HealthInfo West Coast-Te Tai Poutini

Having an anaesthetic

Te kai i te rongoā whakamoe

Anaesthesia stops you feeling pain during surgery or other procedures. It uses medicines called anaesthetics.

Different anaesthetics may be used to relax you, numb an area of your body or make you unconscious during your procedure.

The effects are temporary and your awareness and feeling of pain return when the anaesthesia wears off.

How anaesthetics work

Anaesthetics temporarily block the nerve signals from reaching your brain. This means procedures can be done without you feeling anything. After the anaesthetic wears off, the nerve signals reach your brain and feeling returns to the affected part of your body.

Types of anaesthesia

There are three main types of anaesthesia: local, regional and general.

The type of anaesthesia used depends on the type of procedure or surgery and the results of tests, such as blood tests or an electrocardiogram (ECG). It also depends on your general health. For example, whether you have heart disease or diabetes.

Local anaesthesia

Local anaesthesia is used to numb a small part of your body while you are awake. It is used for minor procedures. You can be given the anaesthetic as an injection or as a spray, cream or gel that is put on the area.

Regional anaesthesia

Regional anaesthesia is used to numb a larger part of your body. This anaesthetic is given as an injection around specific nerves. Regional anaesthesia allows you to stay awake.

There are two types of regional anaesthesia:

• Peripheral nerve block is often used for procedures on your hands, arms, feet, legs or face. It is also useful for pain relief after your operation, as the area stays numb for a few hours.
• Epidural and spinal anaesthesia is given near your spinal cord and the nerves that connect to it. It blocks pain from an entire region of your body, such as your belly, hips or legs. It can be used for pain relief during labour and childbirth, bladder operations and hip replacement surgery.

General anaesthesia

General anaesthesia is used to keep you unconscious during surgery. You feel nothing and have no memory of what happens during your surgery. Your awareness returns when the effects of the anaesthesia wares off. General anaesthesia is given as a gas that you breathe into your lungs and as an injection through a vein.

While you are under a general anaesthetic, a breathing tube is put into your windpipe to help you breathe. The tube is removed as you wake up after surgery. General anaesthesia is used for many operations such as surgery on your heart, lungs and abdomen.

Sedation

Sedation involves using small amounts of anaesthetic medication to make you relaxed and sleepy. But you are not unconscious. Many people having local or regional anaesthesia do not want to be awake for the surgery, so they choose to have sedation as well.

If you have sedation, you will remember little or nothing of the operation. It does not always mean you will have no memory of the operation. Only a general anaesthetic can do that.

Anaesthetists

Anaesthetists are doctors who have specialist training in anaesthesia. Before the procedure, your anaesthetist will discuss the best types of anaesthetic for your procedure. They will plan your anaesthetic and pain control with you, including any preferences you have.

Your anaesthetist will monitor you during your operation and make sure you wake up comfortably afterwards. They may also help with pain relief after the procedure.

Side effects of anaesthetics

Like all medicines, anaesthetics can cause side effects, but they do not last very long. Common side effects of general anaesthesia and some of regional anaesthesia include:

• feeling sick (nausea) or vomiting
• headache
• sore throat and dry lips
• dizziness and feeling faint
• feeling cold or shivering
• itchiness
• pain and bruising at the injection site
• difficulty passing urine (wee)
• aches and pains.

Risks and complications

Usually, having anaesthesia is safe and major problems are rare. Your risk depends on the type of anaesthesia you get, your age, your health and how you respond to the medicines.

Some health problems, such as heart or lung disease, increase your chances of problems from anaesthesia. Being overweight or taking certain medicines can also increase your chance of problems. So can smoking and using illegal drugs. Your anaesthetist will talk with you about the best type of anaesthetic for you and will review the risks, benefits and other choices.

Possible complications include an allergic reaction, permanent nerve damage, heart attack, stroke and organ failure. Also, reawakening during a procedure and the risk of dying. Complications are more likely in the very young, the elderly and people with other health problems.

For a fit person under 60 years of age, the chance of dying due to an anaesthetic complication is approximately 1 in a million. The risk for people over the age of 60 can be higher depending on other health conditions.

Preparing for anaesthesia

Your doctor will let you know what to do the night before and on the day of the procedure. Here are some tips to help you prepare:

• If you smoke, stop smoking. Smoking can increase the risk of anaesthesia-related problems. These can include wound infections, pneumonia (lung infection) and heart attacks. It is best if you quit as soon as possible before your surgery or procedure, preferably a week or more before, but quitting even a day before helps.
• Know when to stop eating and drinking.
• If you take any medicines regularly, ask your doctor or nurse about changes to your medicine routine for the day before or the day of your procedure.
• Plan for going home. Ask a friend or a family member to drive you home. Do not plan to drive yourself if you have had general anaesthesia.

  HealthInfo recommends the following videos

• Australian and New Zealand College of Anaesthetists
  • Preparing for your anaesthesia

    Information about preparing for your anaesthesia.

  • What is anaesthesia?

    Information about what an anaesthetist does and how general anaesthesia works.

  HealthInfo recommends the following pages

• Asthma and Respiratory Foundation NZ – Anaesthetics and asthma fact sheet

  Information about having anaesthetics if you have asthma.

• Australian and New Zealand College of Anaesthetists – About anaesthesia

  Information to help you feel more relaxed about having surgery under anaesthesia.

• NHS Choices – General anaesthesia

  Information about general anaesthetics. Includes how they are given, possible side effects and risks and complications.

Adapted from Healthify He Puna Wairoa as part of a National Health Content Hub collaborative. Last reviewed June 2025.

Sources

Page reference: 98601

Review key: HIHAA-98601