Nerve Root Block Injection
Musculoskeletal (MSK) Services
Last updated: July 2026
Next review: July 2026
What is a Nerve Root Block?
A nerve root block is an injection used to help diagnose and treat pain caused by an irritated or inflamed spinal nerve.
Nerve roots leave the spinal cord and travel into your arms and legs. If a nerve becomes compressed or irritated, it can cause pain, tingling, numbness or weakness.
A nerve root block places medication around the affected nerve to help reduce inflammation and determine whether that nerve is responsible for your symptoms.
Why Might I Need a Nerve Root Block?
Your doctor may recommend a nerve root block to:
- Help identify which nerve is causing your pain.
- Reduce inflammation around the nerve.
- Relieve pain.
- Help you return to normal activities.
- Guide future treatment decisions.
If your pain improves after the injection, it suggests the targeted nerve is likely to be the source of your symptoms.
What Does the Injection Contain?
The injection usually contains:
- Local anaesthetic – provides temporary numbing and works almost immediately.
- Corticosteroid – reduces inflammation and usually begins working within 2–3 days.
Preparing for Your Appointment
In most cases, no special preparation is needed.
You can usually:
- Eat and drink normally.
- Continue taking your usual medication unless advised otherwise.
Please tell your healthcare professional if you:
- Have diabetes.
- Take blood-thinning medication.
- Have any allergies.
- Are pregnant or think you may be pregnant.
People with diabetes may notice a temporary increase in blood sugar levels following the injection.
What Happens During the Procedure?
The procedure is usually carried out in the X-ray department using imaging guidance.
During your appointment:
- You will change into a hospital gown.
- The doctor will explain the procedure and ask for your consent.
- You will lie comfortably on the X-ray table.
- Your skin will be cleaned and numbed with local anaesthetic.
- A fine needle is guided to the affected nerve using X-ray imaging.
- A small amount of contrast dye confirms the correct position.
- The medication is then injected around the nerve root.
The procedure usually takes 15–30 minutes.
Will It Hurt?
You may feel:
- A brief stinging sensation from the local anaesthetic.
- Mild pressure during the injection.
- A short, sharp pain travelling down your arm or leg if the needle briefly touches the nerve.
These sensations usually last only a few seconds.
After Your Injection
After the procedure you will normally remain in the department for 30–60 minutes before going home.
You should:
- Arrange for someone to take you home.
- Avoid driving for the rest of the day.
- Rest if advised by your healthcare professional.
- Gradually return to normal activities.
Your arm or leg may feel numb or weak for up to 24 hours.
Some people notice a temporary increase in pain for 2–3 days before the steroid begins to work.
How Effective Is It?
Many people experience an improvement in their symptoms following a nerve root block.
Pain relief may:
- Begin within a few days.
- Continue improving for up to 6 weeks.
- Last from several weeks to several months.
Some people may benefit from further injections if appropriate.
Are There Any Risks?
Nerve root blocks are generally very safe procedures.
Possible complications include:
- Bruising or bleeding.
- Temporary numbness or weakness.
- Infection.
- Allergic reaction to the contrast dye.
- Temporary increase in pain.
The procedure uses a very small amount of X-ray radiation to guide the needle safely.
When Should I Seek Medical Advice?
Contact your healthcare professional or GP if you experience:
- Increasing redness, swelling or warmth around the injection site.
- Severe or worsening pain.
- Fever or feeling generally unwell.
- Persistent numbness or weakness.
Seek urgent medical advice if you have any serious concerns after your injection.
Further Information
A nerve root block can be an effective way to diagnose and manage nerve-related pain. It is most effective when combined with appropriate rehabilitation, activity modification and ongoing advice from your healthcare team.
