Local anaesthetic

Local anaesthetic is a type of medication used to numb areas of the body during some types of surgery.

The word "anaesthetic" comes from the Greek word meaning the absence or loss of sensation.

Local anaesthetics can be used with a general anaesthetic to aid pain relief after surgery, or in place of a general anaesthetic for certain types of surgery.

How local anaesthetic works

Local anaesthetic causes a complete loss of pain sensation to a specific area of your body without making you lose consciousness.

It works by blocking the nerves from the affected part of your body so that signals can't reach your brain. You will not be able to feel any pain during the procedure but you may still feel some pressure or movement.

It only takes a few minutes to lose feeling in the area where local anaesthetic is given. Your doctor will make sure the area is fully numb before starting the procedure.

It can take a few hours for local anaesthetic to wear off and for full feeling to return. You should be careful not to damage the area during this time. You may be offered painkillers if it's likely you'll be in pain after the anaesthetic has worn off.

How local anaesthetic is used

Local anaesthetic is often used by dentists, surgeons, anaesthetists and GPs when operating on small areas of the body.

Topical anaesthesia

Topical anaesthesia contains local anaesthetic and is available over the counter from pharmacists in the form of creams, sprays and ointments.

For example, gels for mouth ulcers sometimes contain small amounts of benzocaine, which numbs the area around the ulcer.

Eye drops used before some types of eye surgery, such as cataract removal, also contain topical anaesthetic and help numb the eye.

Surgery

Local anaesthetic is also often used during minor surgical procedures such as:

• a filling or wisdom tooth removal
• minor skin surgery, such as the removal of moles and warts and verrucas
• a biopsy – where a sample of tissue is removed for closer examination under a microscope

Local anaesthetic is also sometimes used for more major types of surgery, such as certain types of brain surgery.

For example, it may be used when a brain tumour is located in the area of the brain that controls speech (the Broca's area). As the tumour is removed, the person will need to remain conscious so they can respond to the surgeon’s instructions. This helps the surgeon to minimise the risk of harming the person's speech during the procedure.

Epidural and spinal anaesthetic

Epidural anaesthetic, often referred to as an epidural, is a tube through which local anaesthetic can be continually injected into a specific area of the lower back, known as the epidural space.

Spinal anaesthetic is a single injection into a similar space in the back.

They can be used to numb areas of the body and stop pain being felt, and work by blocking the nerve roots from the spinal cord.

Epidurals and spinals are often used during childbirth to ease the pain of labour, or if a caeseran section is needed. They're also sometimes used for pain relief after major surgery carried out under general anaesthetic.

Read more about epidural anaesthesia.

Peripheral nerve block anaesthetic

A nerve block is an injection of local anaesthetic near a nerve to block pain during and after surgery. It may be used for an operation on a hand, arm or leg so surgery may be carried out without need of a general anaesthetic.

An ultrasound scan is often used to pinpoint the correct nerve, and the injection should not be painful. It usually takes about 30 minutes for the nerve block to become fully effective.

Nerve blocks are sometimes used alongside a general anaesthetic.

Read more about other types of anaesthesia.

Side effects

After having a local anaesthetic you may experience temporary side effects, but there should be no long-lasting problems.

Side effects can include:

• a numb tongue (during dental procedures) 
• dizziness
• blurred vision
• twitching muscles

Tell the healthcare professional in charge of your care if you experience any of these symptoms.

In rare cases, these side effects can develop into more serious complications such as seizures (fits) or cardiac arrest (when the heart stops pumping blood around the body).