Overview

Phenol is an oily substance that has been used to treat chronic pain for many years. It is used for pain that is difficult to control by conventional methods, such as painkillers. Phenol injections can be used to deliberately destroy the nerves that are known to send pain signals. This can result in long-term pain relief. This is done by injecting the phenol around the nerves.

Before you get an appointment to have phenol injections, your doctor might need to do a test of the nerve that they want to treat. This would involve injecting a temporary local anaesthetic to numb the nerve that is believed to send the pain signals.

You should get a significant amount of pain relief, and part of your body might become numb and lose the ability to sense touch. If the pain relief is achieved, and you can tolerate the numbness, your doctor can do the full procedure.

Types of pain this can be used for

We only use phenol to relieve pain in a very small number of painful conditions. These conditions depend on the painful area having a nerve supply that can be safely destroyed. These nerves are usually restricted to those that are involved in sensation. 

Nerve destruction is usually reserved for pain as a result of cancer, because the destruction cannot be reversed. In rare conditions it can be used for pain that is not cancer-related.

Nerves which are involved in movement are not suitable, because destroying them would result in paralysis.

The main benefit of using phenol is that it destroys the nerves, and this can give long-term pain relief.

Your doctor will need to discuss what nerve is intended to be injected, and this will depend on where you have the pain.

Other treatment options

The decision about treatment is shared between you and your doctor. If there are any other treatment options available, your doctor will discuss these with you. Your doctor can give you up-to-date information about the chances of this being a successful treatment for you, and how it fits into the best pathway of care.

If you're unsure about having treatment, more advice and information can be provided. Please speak to your doctor about this.

Side effects and risks

Although in most cases the nerve stops sending signals, the destruction of a nerve can make the nerve more sensitive to pain. This is called deafferentation and the resulting pain can be extremely difficult to treat. It is important that you discuss this with your doctor, and understand this specific risk as it can result in your pain getting worse. This risk depends on the nerves being injected.

This procedure is usually done under local anaesthetic, but if you need sedation too, this has additional risk. You might need sedation if you do not tolerate pain very well.

Common side effects

• Mild tenderness or bruising at the injection sites, that usually settles over a few days.

Rare side effects

• Infection that might need antibiotic treatment. If you get local warmth, redness or tenderness around the injection site of injection or you feel hot and unwell, you should get medical help.
• An allergic reaction to the medicine.
• Some of the injected phenol can enter your circulatory system, which can cause serious heart, breathing or kidney difficulties. This would require immediate management by the healthcare team.
• Nerve injury to a nearby area, caused by unintended spread of the phenol. Your consultant will discuss this with you in detail before the procedure.
• The treatment might not help your pain, and could make it worse.

Giving your permission (consent)

We want to involve you in decisions about your care and treatment. If you decide to go ahead, you will be asked to sign a consent form. This states that you agree to have the treatment and understand what it involves.

If you would like more information about our consent process, please speak to a member of staff caring for you.

Before treatment

It is important to let us know before the procedure if you:

• have an infection in your body (your doctor will delay the treatment until the infection has cleared)
• have started anticoagulant or antiplatelet medicines (blood thinners), such as warfarin, rivaroxaban, heparin or clopidogrel (this might require extra preparation)
• have any allergies

You must also tell the doctor if there is any chance that you could be pregnant.

If you are planning to fly or travel abroad within 2 weeks after the injections, please let your doctor know, as they might want to change the date of the injections.

Please bring your glasses if you need them for reading.

Bring a list of all your current medicines, including any you buy from a pharmacy or shop, and any herbal or homeopathic remedies.

Continue to take your medicines as usual on the treatment day (unless you are taking blood-thinning medicines, such as warfarin, rivaroxaban, heparin, or clopidogrel). If you take a blood-thinning medicine or are unsure if you do, please contact us at least 2 weeks before your treatment so we can help you manage these.

Make sure that you have made arrangements for someone to collect you after the procedure. If you do not, your procedure will probably have to be cancelled. It is unsafe for you to drive immediately after the procedure. If you do, your motor insurance will not be valid.

During treatment

Doctors give these injections in slightly different ways, but this is generally what will happen.

• You might be asked to show your doctor where the painful area is, and this will be marked so that we inject the correct side. Please do not feel offended if you are asked multiple times, as we want to minimise the risk of any mistake.
• Observations, such as blood pressure and pulse rate, might be taken.
• A small needle (cannula) might be placed in the back of your hand.
• You will be carefully positioned and the skin around the injection site will be cleaned with an antiseptic solution or spray. This can feel very cold.
• An X-ray machine (or another form of image guidance) will be used if needed to make sure we inject you accurately.
• You will feel a stinging sensation as local anaesthetic is injected to numb the skin and surrounding tissues. Your doctor will warn you of this first. If you are having sedation (medicine to make you sleep through the procedure) this will not apply.
• The doctor will direct the needles to the area suspected to be a source of pain.
• When the injections are made, you might feel pressure, tightness or a pushing sensation. If there is any discomfort, let the doctor know.
• You might be asked how your pain is during the procedure, and about any effects of the injection.

After the treatment

You will be taken to a recovery ward where nursing staff will observe and monitor you. If you have had sedation you might feel a little drowsy and want to sleep. You will be told when you can get dressed, and be given help to make sure that you can stand safely after the procedure.

The length of time you stay in recovery will depend on the injections you have had. If there is any pain from the injection you can ask for pain relief.

Leaving hospital

You can usually leave hospital within a few hours after the injections, and sometimes much sooner.

Ideally, you should arrange for someone to stay with you for 24 hours after your treatment. If this is not possible, you should at least have access to a phone. You should not:

• drive
• operate machinery
• sign legal documents
• provide childcare unsupervised
• drink alcohol

Keep the injection sites dry for 24 hours after the procedure.

Do not worry if your pain feels worse for a few days, as this sometimes happens. If there is any pain from the injection, you can use regular painkillers, such as paracetamol, and this pain will subside with time. Always follow the instructions on the packet.

Returning to work

You can return to work and exercise as soon as you feel able to. If you need more than 7 days off work, you will have to see your GP for a fit note.

Follow-up appointments

You will receive a letter with details of your follow-up appointment. It will be a phone call with a specialist nurse, or in clinic with a consultant. If you have not heard from us within 10 weeks after the procedure, please contact us, phone 020 7188 4714, Monday to Friday, 9am to 5pm.