Anaesthesia explained

Published: 31/07/2019

Types of anaesthesia

Local anaesthesia 

A local anaesthetic numbs a small part of the body. It is used when the nerves can be easily reached by drops, sprays, ointments or injections. You stay conscious, but free from pain. Common examples of surgery under local anaesthetic are having teeth removed and some common operations on the eye.

Regional anaesthesia 

This is when local anaesthetic is injected near to the nerves which supply a larger or deeper area of the body. The area of the body affected becomes numb.

Spinal and epidural anaesthetics 

These are the most common regional anaesthetics. These injections can be used for operations on the lower body, such as Caesarian section, bladder operations, or replacing a hip. You stay conscious, but free from pain.

Other types of regional anaesthesia 

Other regional anaesthetics involve an injection placed near to a nerve or group of nerves, for example in the arm or leg. This is often called a ‘nerve block’. This can allow you to have the operation without a general anaesthetic. 

Nerve blocks are also useful for pain relief after the operation, as the area will stay numb for a number of hours.

For more information, see our leaflet on nerve blocks on the shoulder, arm, hand.


Sedation involves using small amounts of anaesthetic drugs to produce a ‘sleep-like’ state. It makes you physically and mentally relaxed, but not unconscious. 

Many people having a local or regional anaesthetic do not want to be awake for surgery. They choose to have sedation as well.  

If you have sedation, you may remember little or nothing about the operation or procedure. However, sedation does not guarantee that you will have no memory of the operation. Only a general anaesthetic can do that.

For more information, see our leaflet on sedation explained.

General anaesthesia

General anaesthesia is a state of controlled unconsciousness during which you feel nothing. You will have no memory of what happens while you are anaesthetised. 

A general anaesthetic is essential for a very wide range of operations. This includes all major operations on the heart or lungs or in the abdomen, and most operations on the brain or the major arteries. It is also normally needed for laparoscopic (keyhole) operations on the abdomen. 

Anaesthetic drugs are injected into a vein, or anaesthetic gases are given for the patient to breathe. These drugs stop the brain from responding to sensory messages travelling from nerves in the body.

Anaesthetic unconsciousness is different from a natural sleep. You cannot be woken from an anaesthetic until the drugs are stopped and their effects wear off.

While you are unconscious, the team in theatre look after you with great care. Your anaesthetist stays near to you all the time.


Anaesthetic techniques are often combined. For example, a regional anaesthetic may be given for pain relief afterwards, and a general anaesthetic makes sure you remember nothing.