Nerve block injections are used in pain medicine to target specific nerves that may be carrying pain signals from an affected part of the body. Depending on the type of pain and the nerve involved, an injection may be used to provide temporary pain relief, help identify the source of symptoms or support a wider treatment and rehabilitation plan.
There are many different types of nerve block, and the term does not describe one single procedure. A block used for persistent headache, for example, targets different nerves from an injection used for pain travelling from the lower back into the leg.
This guide explains what nerve block injections are, the conditions they may be used for, how they are performed, what patients can expect afterwards and why careful assessment is important before deciding whether an injection is appropriate.
Important: This article provides general information and does not replace an individual medical assessment. New or rapidly worsening weakness, loss of bladder or bowel control, numbness around the genitals or buttocks, severe unexplained chest pain, sudden shortness of breath or other concerning neurological symptoms require urgent medical attention.
What is a nerve block injection?
A nerve block is an injection placed close to a particular nerve or group of nerves. The aim is to temporarily alter the transmission of pain signals from the targeted area.
Depending on the procedure and its purpose, the injected medicine may include a local anaesthetic, a corticosteroid or a combination of medicines. Local anaesthetic temporarily reduces nerve signalling, while corticosteroid may be used in selected procedures when inflammation is thought to contribute to the symptoms.
Nerve blocks are used in several areas of medicine. Anaesthetists commonly use them to provide anaesthesia or postoperative pain relief. In specialist pain medicine, targeted injections may also be considered as part of the assessment and management of persistent pain.
The exact technique, medicine and imaging method depend on which nerve is being targeted and the clinical reason for performing the procedure.
How do nerve blocks work?
Nerves transmit electrical and chemical signals between the body and the central nervous system. When a nerve becomes irritated, compressed or sensitised, these signals may be experienced as pain.
A local anaesthetic placed close to the nerve temporarily interrupts the transmission of these signals. This may reduce pain for a limited period while the anaesthetic remains active.
Where a corticosteroid is included, the intention may also be to reduce inflammation around the affected nerve or nearby tissues. Any improvement from the steroid component may take longer to develop than the immediate effect of local anaesthetic.
Importantly, a nerve block does not necessarily correct the underlying cause of pain. Its role depends on the diagnosis and may be therapeutic, diagnostic or both.
What conditions can nerve block injections be used for?
Nerve blocks may be considered for several different pain conditions. Whether one is appropriate depends on the location, cause and characteristics of the pain.
Examples include:
- Persistent nerve or neuropathic pain
- Sciatica and selected forms of radicular leg pain
- Neck and arm pain associated with nerve irritation
- Occipital neuralgia and selected headache disorders
- Persistent pain following some operations
- Complex regional pain syndrome in selected circumstances
- Some forms of facial pain
- Pain associated with particular peripheral nerves
- Certain chronic spinal pain conditions
Having one of these conditions does not automatically mean that a nerve block is the appropriate treatment. Similar symptoms can arise from different structures, so identifying the likely pain generator is an important part of deciding whether an injection is likely to be useful.
What are the different types of nerve block?
The term “nerve block” covers several procedures. Some target peripheral nerves outside the spine, while others target spinal nerve roots or nerves associated with particular joints.
Peripheral nerve blocks
A peripheral nerve block targets a nerve outside the brain and spinal cord. The injection is placed close to the nerve believed to be carrying pain signals from a particular region.
Depending on the nerve involved, ultrasound or another form of image guidance may be used to help identify surrounding structures and position the needle accurately.
Selective nerve root blocks
A selective nerve root block targets a spinal nerve as it exits the spine. It may be considered when symptoms such as pain, tingling or altered sensation follow the distribution of a particular nerve root.
For example, irritation of a lumbar nerve root can produce pain travelling from the lower back or buttock into the leg. A carefully targeted injection may sometimes help determine whether that nerve is contributing to the symptoms as well as potentially reducing pain.
Occipital nerve blocks
The greater and lesser occipital nerves provide sensation to parts of the back and top of the head. Occipital nerve blocks may be considered in selected patients with occipital neuralgia or certain persistent headache patterns.
Because headaches have many possible causes, appropriate assessment should take place before assuming that the occipital nerves are responsible.
Sympathetic nerve blocks
The sympathetic nervous system helps regulate functions including blood flow, sweating and temperature. In selected pain conditions, particularly where abnormal sympathetic activity may contribute to symptoms, a sympathetic block may be considered.
These are specialist procedures and are not routine treatments for general back, neck or joint pain.
Can a nerve block help diagnose the source of pain?
Yes. Some nerve blocks can have a diagnostic role as well as a therapeutic one.
Pain can be difficult to localise because abnormalities seen on scans do not always cause symptoms. Conversely, significant pain may occur without a dramatic abnormality on imaging.
If examination, symptoms and imaging suggest that a particular nerve may be responsible, temporarily reducing signals from that nerve can provide additional clinical information.
The clinician may consider:
- How much the pain changed after the injection
- Which part of the pain improved
- How quickly any improvement occurred
- How long the effect lasted
- Whether function or movement improved
A response to an injection is interpreted alongside the clinical history, examination and investigations. It should not normally be treated as an isolated test result.
How do I know whether my pain is nerve pain?
Nerve pain, also called neuropathic pain, can feel different from ordinary muscular or joint pain.
Patients may describe:
- Burning pain
- Shooting or stabbing sensations
- Electric-shock-like pain
- Tingling or pins and needles
- Numbness or altered sensation
- Pain caused by light touch
- Unusual hot or cold sensations
- Pain travelling along a particular path
However, symptoms alone cannot always establish the diagnosis. Muscles, joints, discs and other structures can produce overlapping pain patterns, and some patients have a combination of neuropathic and mechanical pain.
What happens before a nerve block injection?
A specialist assessment should normally take place before the procedure is recommended.
The clinician may review:
- Where the pain starts and where it travels
- How long symptoms have been present
- Whether there is numbness or weakness
- Previous injuries or operations
- Previous injections and their effects
- Current medication
- Relevant medical conditions
- MRI, CT, X-ray or other investigation results
Patients should tell the clinical team about all medication they take, particularly anticoagulant or antiplatelet medicines that affect blood clotting. These medicines should not be stopped without specific medical instructions.
Allergies, previous reactions to injections or contrast agents, pregnancy or possible pregnancy and significant infections or recent illness should also be discussed before the procedure.
What happens during a nerve block injection?
The exact procedure varies according to the nerve being treated.
In general, the patient is positioned so that the clinician can safely access the target area. The skin is cleaned with antiseptic solution and local anaesthetic may be used to numb the skin before the main injection.
The clinician then guides a needle towards the target nerve or nerve root. Depending on the procedure, guidance may involve:
- Ultrasound
- X-ray or fluoroscopy
- Anatomical landmarks
- Other specialist imaging techniques
Image guidance can help the clinician identify the relevant anatomy and position the needle accurately while avoiding important surrounding structures.
Once the needle is appropriately positioned, the selected medicine is injected. The procedure itself is often relatively brief, although preparation, imaging and observation afterwards mean the overall appointment takes longer.
Are nerve block injections painful?
Patients commonly feel a brief stinging sensation when local anaesthetic is injected into the skin. During needle positioning or injection, there may also be pressure, tightness or temporary discomfort.
Some people experience a short reproduction of their familiar pain or a tingling sensation when the needle approaches the target nerve.
The experience varies according to the location of the nerve, the type of procedure and individual sensitivity.
Patients should tell the clinician if they experience unexpected severe pain or other unusual symptoms during the procedure.
How quickly does a nerve block work?
If local anaesthetic is used, some patients notice an effect within minutes. The area supplied by the targeted nerve may temporarily feel numb, heavy or different.
This early response usually reflects the local anaesthetic rather than the longer-term outcome of the procedure.
If a corticosteroid has also been used, any additional effect may take several days to develop. There may therefore be a period after the local anaesthetic wears off when the original symptoms return before any later benefit becomes apparent.
Not every patient experiences significant improvement.
How long does a nerve block last?
There is no single duration that applies to every nerve block.
The local anaesthetic itself generally has a temporary effect. However, pain relief following an appropriately selected injection may sometimes continue beyond the period during which the local anaesthetic is active.
The duration of benefit can vary from a short period to substantially longer depending on:
- The condition being treated
- Which nerve is targeted
- The medicine used
- The degree of nerve irritation or inflammation
- Whether the underlying cause remains present
- The individual patient’s response
Some patients obtain meaningful relief, some experience only short-term improvement and others obtain little or no benefit.
A nerve block should therefore not be presented as a guaranteed or permanent solution.
What happens after a nerve block?
Patients may be observed for a period after the injection, depending on the procedure and medicines used.
Temporary effects can include:
- Numbness around the treated area
- Heaviness or weakness in the affected limb
- Mild soreness around the injection site
- Temporary alteration in normal sensation
If the block affects strength or sensation in a leg or arm, additional precautions may be necessary until normal function returns.
Instructions regarding driving, work, exercise, bathing and normal activity depend on the type of procedure. Patients should follow the specific discharge advice given by their treating clinic rather than assuming that instructions for one type of nerve block apply to another.
Can I drive after a nerve block injection?
Patients should not assume that they will be able to drive themselves home after a nerve block.
Some procedures can temporarily affect sensation, coordination or muscle strength. Sedative medication may also be used in certain circumstances.
The clinic should provide procedure-specific advice about transport before the appointment. Where driving is restricted, patients should arrange for an appropriate adult to take them home.
What are the risks of a nerve block?
Nerve blocks are established medical procedures, but no injection is completely free from risk.
Possible side effects and complications depend on the location and type of block and may include:
- Temporary soreness or bruising at the injection site
- Temporary numbness or weakness
- Bleeding or haematoma
- Infection
- Temporary increase in pain
- Allergic reaction to medication
- Unintended spread of local anaesthetic
- Blood-vessel injury
- Nerve irritation or, rarely, nerve injury
Some specialist spinal or deep nerve blocks have additional procedure-specific risks. These should be explained during the consent process.
Patients taking medicines that affect blood clotting may require particular planning because bleeding near certain nerves or spinal structures can have serious consequences.
Can a nerve block make pain worse?
A temporary increase in discomfort can occur after an injection. This may result from the needle itself, temporary tissue irritation or the return of the original pain after the local anaesthetic wears off.
This does not necessarily mean that the procedure has caused damage.
However, severe or progressively worsening pain, new persistent weakness, significant swelling, fever or other unexpected symptoms should be reported to the treating team promptly.
Are nerve blocks a permanent treatment?
Usually not.
A nerve block generally aims to temporarily modify pain signalling rather than permanently disable a nerve. The duration and degree of benefit vary considerably between patients.
Temporary pain reduction can still be clinically useful. For example, it may allow a patient to participate more effectively in physiotherapy, improve movement, sleep more comfortably or reduce a severe pain flare while other treatment is undertaken.
In some circumstances, the response to a temporary diagnostic block may also help determine whether another targeted treatment should be considered.
What if a nerve block does not work?
A lack of meaningful pain relief does not necessarily mean that nothing else can be done.
It may suggest that:
- The targeted nerve is not the main source of pain
- Several structures are contributing to the symptoms
- The pain mechanism is different from that initially suspected
- The underlying condition requires another form of treatment
- The pain has become persistent and requires a broader multidisciplinary approach
The result should be reviewed in the context of the original diagnosis rather than simply repeating injections without reassessment.
What other treatments may be considered?
A nerve block is usually one possible component of pain management rather than a complete treatment plan.
Depending on the diagnosis, other approaches may include:
- Physiotherapy and rehabilitation
- Activity and lifestyle modification
- Medication review
- Medicines used for neuropathic pain
- Psychological pain-management strategies
- Epidural or other targeted spinal injections
- Radiofrequency procedures for appropriate pain generators
- Neuromodulation in selected persistent pain conditions
- Surgical assessment when a correctable structural problem is identified
The appropriate treatment depends on the cause of the symptoms, not simply their severity.
When should you see a pain specialist?
Specialist assessment may be appropriate when pain:
- Persists despite initial treatment
- Significantly affects sleep, work or normal activity
- Has features suggesting neuropathic pain
- Travels along a particular nerve distribution
- Returns after previous treatment
- Has an unclear cause despite previous investigation
- Requires consideration of an interventional pain procedure
A specialist pain consultation does not automatically lead to an injection. The first objective is to understand the likely source and mechanism of the pain and then discuss appropriate treatment options.
Questions to ask before having a nerve block
Patients considering an injection may find it useful to ask:
- Which nerve do you believe is causing my pain?
- Is this injection diagnostic, therapeutic or both?
- What medicine will be injected?
- Will ultrasound or X-ray guidance be used?
- What improvement would be considered a successful response?
- How long might the effect last?
- What are the specific risks of this particular block?
- Do I need to change any medication before the procedure?
- Can I drive or work afterwards?
- What happens if the injection does not help?
Preparing for a specialist pain consultation
Where possible, bring:
- A current medication list
- Relevant MRI, CT or X-ray reports
- Previous clinic or hospital letters
- Details of previous injections and how long they helped
- Information about previous surgery
- A description of where the pain starts and travels
- Details of any numbness, tingling or weakness
This information can help the consultant determine whether the symptoms are likely to arise from a particular nerve and whether a targeted procedure is appropriate.
Specialist assessment for nerve pain
Successful pain treatment begins with identifying the most likely source and mechanism of the symptoms. A nerve block may be useful for selected patients, but it should be considered within the wider clinical picture rather than as an isolated treatment.
At Pain Consultants, patients can receive a consultant-led assessment for persistent nerve, spinal and musculoskeletal pain. Where appropriate, treatment options may include medication review, rehabilitation, targeted image-guided procedures and other specialist pain-management treatments.
Book a pain management consultation to discuss persistent nerve pain and whether a targeted treatment may be appropriate.
Frequently asked questions
What is a nerve block injection used for?
A nerve block places medication close to a selected nerve or group of nerves. In pain medicine, it may be used to temporarily reduce pain, help determine whether a particular nerve is contributing to symptoms or support rehabilitation and other treatment.
How long does a nerve block injection last?
The duration varies according to the type of block, medicine used, condition being treated and individual response. The local anaesthetic has a temporary effect, while any overall pain relief may last for a different period. Some patients experience meaningful longer-lasting improvement while others have limited or no benefit.
How painful is a nerve block injection?
There is usually brief discomfort when the skin is numbed, followed by possible pressure or temporary discomfort while the needle is positioned. The experience varies according to the location and type of block.
Are you awake during a nerve block?
Many pain-management nerve blocks are performed while the patient is awake using local anaesthetic. Sedation may be appropriate for some procedures or patients. The exact approach should be discussed before treatment.
Can nerve blocks help sciatica?
Selected patients with pain caused by irritation of a spinal nerve may be considered for a targeted nerve-root or related spinal injection. Sciatica has several possible causes, so assessment and appropriate imaging may be needed before deciding whether an injection is suitable.
Can a nerve block diagnose where pain is coming from?
Some blocks are used partly for diagnostic purposes. If temporarily blocking a suspected nerve substantially changes the patient’s usual pain, that response may provide useful information. The result must still be interpreted alongside the history, examination and imaging.
What happens if a nerve block does not work?
The diagnosis and treatment plan should be reviewed. The targeted nerve may not be the main source of pain, several structures may be involved or another treatment approach may be more appropriate. An unsuccessful block does not by itself mean that no further treatment options exist.
How many nerve block injections can you have?
There is no appropriate universal number for every patient. Whether another injection should be performed depends on the type of block, medicines used, previous response, diagnosis, risks and overall treatment plan. Repeated procedures should have a clear clinical reason rather than being performed automatically.