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Nerve Root Block

Date issued: August 2023

Review date: August 2025

Ref: B-465/Pain Management/Nerve Root Block v3

PDF:  Nerve Root Block final August 2023 v3.pdf [pdf] 155KB

What is a nerve root block?

  • This is an injection of local anaesthetic with / without steroid to a nerve in your low back.

  • It is done both to see which nerve is causing the pain in your leg and to relieve your pain.

Why am I receiving it?

The doctor in the pain clinic has decided to offer you this treatment because it might help to decrease the amount of pain you are feeling.

How does it work?

Local anaesthetics and steroid reduce the pain in the area of the injection helping to both turn off the sensitivity of the nerves in that area and decrease any chronic inflammation.

What are the side-effects of steroids?

  • There are effects on the rest of the body using steroids but these are minimal if used cautiously.

  • Temporary side effects from the steroids are raised blood pressure and increased sugar levels in diabetics.

  • Prolonged side effects, usually if steroids are used repeatedly, include bone fractures, stomach irritation and bleeding, and reduced ability to fight infection.

What does the treatment involve ?

A nerve root block is performed as a day case procedure.

You must fast unless otherwise advised.

If you are taking any medication to thin the blood, such as Warfarin, Clopidogrel, Rivaroxaban, Dabigatran  or you have a blood clotting disorder please inform your Pain Consultant or the pain nurse prior to attending for your injection as your medication may need to be stopped before the injection to prevent bleeding.

You will be seen by one of the Pain Consultants who will explain the treatment and answer any questions that you may have.

You will need to lie or sit in an appropriate position to allow the doctor to do the procedure.  The skin over the area will be cleaned with antiseptic and a local anaesthetic injected into the skin to numb the area. The procedure uses x-ray to guide the doctor in placing the needle.

There may be some discomfort at the time of the injection. You will have a small dressing on your back to cover the injection site, this may be removed after 24 hours but do not worry if it should fall off sooner.

What should I expect immediately after the injection?

It is common after this injection, to have a numb/heavy leg. You may feel as though the area that has been injected is a little bruised and also you may experience an increase in the level of your pain for a few days. This is normal, but it will quickly resolve and you can continue to take your normal painkillers for pain that you have. A small percentage of patients may experience an increased level of pain for much longer.

Post procedure advice

You must not drive yourself home and you should have someone with you at home for 24 hours. A temporary flare of pain is sometimes reported but this should last only up to a week or so. If you are diabetic check your blood sugars regularly for a couple of days as the steroid can affect them. Slowly start to increase your movement in the weeks following the injection.


If you have new leg weakness, or new problems with bowel or bladder control with new back pain or fever in the weeks following your injection please seek urgent medical advice.

You should either ring:    

  • Your GP.

  • NHS 111.

  • Pain Clinic (in office hours) 01752 437706.

  • Or attend Derriford Emergency Department.

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