What is a local anaesthetic?

A local anaesthetic is a medicine that numbs a part of your body for a short time. Local anaesthetics do not make you unconscious like a general anaesthetic. You will be awake and aware of what is happening around you, but you won’t feel pain in the treated area.

A local anaesthetic has fewer side effects than a general anaesthetic. It is usually preferred when only a small part of your body needs to be numbed. Once it takes effect, you won’t feel pain in the area where the local anaesthetic is injected or applied. You may still feel some pressure or movement.

How does local anaesthetic work?

A local anaesthetic works by blocking the nerves in the area where it is injected or applied. This stops nerves from sending pain signals to your brain and makes the treated area feel numb. The numbing effect usually lasts for a few hours.

If you have an infection in the area being treated, a local anaesthetic may not be appropriate, as the infection may affect its effectiveness.

What are the different types of local anaesthetic?

Local anaesthetics come in different forms, such as creams, drops, sprays or injections. They are usually used for procedures on small areas of your body, such as small skin or nail procedures or the extraction of a tooth. It may also be used to numb the area around a laceration (cut) before having stitches.

Topical anaesthetic

Topical anaesthetics are available as liquids, creams, ointments or sprays. They are applied on the skin’s surface. Some types of minor eye surgery can be performed using anaesthetic eye drops.

Some topical anaesthetics are available over-the-counter in pharmacies.

Anaesthetic injections

With anaesthetic injections, a numbing medicine is injected near the area undergoing the procedure. It may be the only type of anaesthetic used, or it may be used together with sedation or general anaesthesia.

Epidural and spinal anaesthesia

An epidural block and a spinal block both involve the injection of local anaesthetic medicines into the area of the spine surrounding the spinal cord.

Epidural and spinal anaesthetics can be used to stop pain during labour or for a caesarean section. They can also be used for surgery to your legs or the lower part of your abdomen.

Nerve block

A nerve block involves injecting local anaesthetic near major nerves, for example nerves that receive pain signals from your eye, leg or arm. This injection can numb a large area and may be used for surgery in these areas.

How do I prepare for a local anaesthetic?

All anaesthetics have risks, so talk to your doctor about your options. Discuss any health conditions or allergies you have.

Your doctor might advise you:

• to quit smoking as early as possible before surgery
• not to drink alcohol from the day before surgery
• what medicines you should not take before and on the day of surgery

You can also ask about how to manage pain after the local anaesthetic has worn off and about any other concerns or worries you may have.

Read more on questions to ask before surgery and on preparing for surgery.

What can I expect after having a local anaesthetic?

The treated area may stay numb or weak for up to 24 hours. Be careful not to knock the area or touch anything hot while it is still numb, as you won’t be able to feel an injury occurring. Get help if it is hard for you to walk. Talk to your doctor if the numbness is not gone after 24 hours.

What are the possible complications of having a local anaesthetic?

The most common complication of having a local anaesthetic is pain or bruising on your skin where the medicine was injected.

Less common complications include:

• temporary nerve damage — this can make a part of your body feel weak or numb for an extended period of time
• not becoming numb enough, in which case your doctor may need to use a different type of anaesthetic
• injury to arteries, veins or muscles in the area

Although it is rare, there is a chance of severe complications. These may include permanent nerve damage, seizures, heart attack or stroke.

Resources and support

Read the fact sheet about types of anaesthesia from the Australian and New Zealand College of Anaesthetists.

Queensland Government has a patient information sheet about local anaesthetic. It outlines how to prepare, risks and what to expect after an anaesthetic.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.