Anaesthetics Overview

This page will provide you with information about anaesthetics. For further details, please speak to your consultant.

What is an anaesthetic?

Anaesthetics are drugs specially designed to put the patient to sleep and cause a complete loss of sensation.

Some specific anaesthetics include:

  • General – this causes the patient to fall into a heavy sleep. They will be completely oblivious to what is happening whilst they are asleep and will not remember what has happened when they wake up.
  • Epidural/spinal – this takes the form of having local anaesthetic, and sometimes other painkillers, injected into the spinal cord. This provides pain relief to specific areas.
  • Local – this stops nerves from working for the duration of the operation/procedure so that the patient has a loss of sensation in a specific area. It is usually injected near the area but can also be used to numb an arm or leg (a nerve block).

The anaesthetist in charge will run through the different options and recommend the most suitable choice based on the operation being performed and the health of the patient.

What are the benefits of anaesthetics?

If a patient requires an operation or procedure that will cause them pain, then anaesthetics can allow the surgeon or doctor to perform the procedure safely. It will prevent the patient from moving and allow the muscles to completely relax, making it easier for the healthcare team to do their job.

If a patient is already in pain from surgery or a pre-existing condition then anaesthetics can provide pain relief and reduce discomfort.

Who administers the drugs?

A general, epidural or spinal anaesthetic will be administered by an anaesthetist – that is a doctor specially trained in the field of pain relief – usually with a healthcare professional also on hand.

Local anaesthetic can be administered by a surgeon or anaesthetist.

General anaesthetics

How are they administered?

Injection is the most common way to administer anaesthetics. This is done with a drip (small tube) inserted into a vein. Within 30 seconds the patient will be asleep.

The injection may be uncomfortable at the time but this feeling will diminish when the patient wakes up.

Some patients may opt to inhale the anaesthetic as a gas with the use of a face mask. This will also send the patient to sleep within 30 seconds.

Patients will be kept in a state of sedation by injecting or inhaling more anaesthetics as the operation or procedure goes on. The anaesthetic will be allowed to wear off once the operation or procedure finishes; some patients will be given extra painkillers at this point to help with any discomfort or sickness they may feel.

Spinal/epidural anaesthetics

How are they administered?

An epidural temporarily numbs the nerves and this provides pain relief. This involves inserting a small catheter (small tube) into the epidural space near the spinal cord (see figure 1).

Figure 1

An epidural catheter being inserted

a. A needle is inserted into the back

b. When the needle reaches the epidural space the position is checked

c. A catheter is inserted into the epidural space and the needle removed

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As the majority of the body’s nerves pass through the epidural space this is an effective form of pain relief, with local anaesthetics injected through the catheter to numb the nerves.

Epidurals continue to hold their effect with extra doses being administered when necessary, or with a continual low dose (an infusion) being administered throughout the operation/procedure.

A spinal anaesthetic is similar but is usually performed by injecting one dose of painkiller into the fluid sac that surrounds the spinal cord.

Local anaesthetics

How are they administered?

In its most simple form, local anaesthetics are injected into the area where the operation or procedure is to take place. This can sting/burn initially but the area will swiftly go numb.

If a nerve block is required, local anaesthetics and other painkillers are injected near the body’s major nerves linking to the limb requiring treatment. Some painkillers can be taken in combination with the anaesthetics to provide the most pain relief with as little discomfort.

Local anaesthetic is sometimes given prior to a general anaesthetic.

Risks and complications

Any risks or complications will be discussed in advance of your treatment with your expert consultant.


Anaesthetics are a safe and highly effective method of pain relief. There are a number of different forms available and each will provide pain relief during an operation or procedure.



EIDO Healthcare Limited – The operation and treatment information on this website is produced using information from EIDO Healthcare Ltd and is licensed by Aspen Healthcare.

The information should not replace advice that your relevant health professional would give you.