Pain Block Injection

A pain block injection is a procedure in which a doctor injects a local anaesthetic (a numbing medicine) — sometimes combined with a steroid (an anti-inflammatory medicine) — very close to a specific nerve or group of nerves to stop pain signals from reaching the brain.

Nerves carry pain messages from an injured or inflamed part of the body up to the brain. By placing numbing medicine right next to the nerve responsible for a particular area, the doctor can interrupt those messages. The result is that the patient feels little or no pain in that area for hours, days, or sometimes longer, depending on the medicines used and the individual patient's response.

Pain block injections are used when pain is severe, persistent, or has not responded well enough to oral medicines alone. They can serve two purposes: relieving pain so the patient can function or sleep, and helping the doctor confirm exactly which nerve is causing the problem.

• Chronic back or neck pain, including pain caused by a herniated disc (a slipped disc pressing on a nerve)
• Sciatica (sharp pain that travels down the leg along the sciatic nerve)
• Joint pain from osteoarthritis (wear-and-tear of a joint) or rheumatoid arthritis (an immune system attack on joints)
• Nerve pain (neuropathic pain) after an injury, surgery, or illness such as shingles
• Pain from cancer affecting bones or nerves
• Complex regional pain syndrome (CRPS), a condition where severe, burning pain lingers long after an injury
• Headache disorders such as cluster headaches or occipital neuralgia (pain at the back of the head caused by an irritated nerve)
• Post-operative pain management when strong oral medicines are not sufficient or suitable
• Pain during labour and childbirth (epidural block)

This procedure may not be suitable in every situation. Doctors generally avoid it when any of the following apply:

• Active infection at or near the injection site
• Blood clotting disorders or the patient is taking blood thinners that cannot be paused safely
• Allergy to local anaesthetic medicines
• Certain anatomical (structural) abnormalities that make safe needle placement difficult
• The patient is unable to cooperate or remain still enough during the procedure

Pain block injections are generally considered safe when performed by a trained specialist, but like any procedure that involves a needle entering the body, they carry some recognised risks.

• Temporary soreness, swelling, or bruising at the injection site — the most common effect, usually settling within a few days
• Temporary numbness or weakness in a limb beyond the intended area, which usually wears off as the medicine clears
• Inadequate pain relief — the block may not work as expected in some patients
• Infection at the injection site, though this is uncommon when sterile technique is used
• Bleeding or haematoma (a pocket of blood) at the injection site, more likely in patients with clotting issues
• Accidental injection into a blood vessel, which can cause brief dizziness, ringing in the ears, or, rarely, a more serious reaction
• Nerve irritation or, very rarely, nerve injury, causing temporary or persistent numbness, tingling, or weakness
• Dural puncture headache (a specific type of headache caused by leakage of spinal fluid) if a block near the spine is performed
• Allergic reaction to the local anaesthetic or steroid used
• With repeated steroid injections over time: possible thinning of nearby tissue or temporary changes in blood sugar levels

Good preparation helps the procedure go smoothly and reduces the chance of complications. The exact instructions will depend on the type of block, where it is being placed, and the patient's overall health — the care team will give specific guidance.

Before the procedure, patients are usually asked to do the following:

• Fasting: for blocks done under sedation (light sleep medicine given through a drip), most hospitals ask patients not to eat solid food for several hours beforehand. For blocks done under local anaesthetic alone while fully awake, fasting rules may be less strict — the team will confirm.
• Medicines: blood thinners are often paused for a set period before the injection to reduce bleeding risk. The care team will advise which medicines to continue and which to hold.
• Alcohol and smoking: avoiding alcohol for at least 24 hours before is usually recommended; smoking can affect healing and circulation, so the team may advise stopping temporarily.
• Arrange transport: because sedation or the block itself may make driving unsafe, patients are usually asked to arrange for someone to take them home.

Tests that are commonly ordered before the procedure include:

• Blood tests to check clotting ability and general health markers
• Review of any imaging already done (MRI, CT, or X-ray) to identify the exact nerve target
• Blood pressure and heart rate check on the day
• Allergy screening if there is any history of reactions to local anaesthetics

On the day of the procedure, the steps typically follow this order — though the exact sequence and number of steps may vary between hospitals and types of block:

• 1. The patient changes into a gown and an intravenous (IV) line (a small tube placed into a vein) is inserted in case medicine needs to be given quickly.
• 2. The patient is positioned on a procedure table — lying face down, on their side, or sitting, depending on where the block is to be placed.
• 3. The target area of skin is cleaned thoroughly with antiseptic (germ-killing) solution.
• 4. The doctor uses imaging guidance — most commonly fluoroscopy (live X-ray), ultrasound, or CT — to see exactly where the needle tip needs to go.
• 5. A small amount of local anaesthetic is injected into the skin to numb the surface before the main needle is inserted.
• 6. The main needle is carefully advanced to the target nerve or nerve cluster, guided by the imaging.
• 7. A small amount of contrast dye (a liquid that shows up on X-ray) may be injected first to confirm the needle is in the correct position.
• 8. The pain-blocking medicine — and steroid if planned — is slowly injected.
• 9. The needle is removed, and light pressure is applied to the site.
• 10. The patient is moved to a recovery area for monitoring.

After the injection, the patient is monitored in a recovery area — usually for 30 minutes to a couple of hours — while the care team checks blood pressure, heart rate, and the effect on pain and limb strength. How quickly a patient recovers and returns to normal activity depends on the type of block, the medicines used, and the individual.

• Monitoring: before discharge, the team will confirm that any numbness or weakness from the block is wearing off appropriately and that there are no signs of an adverse reaction.
• Going home: most patients go home the same day. Because residual numbness can affect balance and coordination, patients should not drive or operate machinery until the doctor confirms it is safe — usually once full sensation and strength have returned.
• Activity restrictions: for the first day or two, heavy lifting, strenuous exercise, and prolonged standing or sitting in one position are usually discouraged. Gentle movement as tolerated is generally encouraged.
• Injection site care: the site may be sore for a day or two. Keeping it clean and dry, and avoiding submerging it in water (such as a swimming pool or bathtub) for the first 24–48 hours is usually advised. A small dressing or plaster covers the site.
• Pain response: it is normal for pain to feel slightly worse for a day or two after the injection — especially if a steroid was used — before improvement begins. This is sometimes called a 'steroid flare'.
• Medicines: the care team will advise whether any existing pain medicines should be continued, adjusted, or tapered. Patients should not change their own medicine routine without guidance.
• Warning signs to report promptly: fever, increasing redness or discharge at the injection site, severe headache (especially one that worsens when sitting or standing), new or worsening numbness, difficulty breathing, or chest pain.
• Follow-up appointment: a follow-up visit is usually scheduled within a few weeks so the doctor can assess how well the block worked, whether a repeat injection might help, and whether further treatment is needed.
• Lifestyle: physiotherapy (movement exercises guided by a specialist), weight management, and other lifestyle adjustments are often recommended alongside the injection to address the underlying cause of pain rather than only the symptom.