Two uses (to relieve and to check), the types of injection, the day of the procedure, benefit and safety, and your next step if it works or not.
A nerve block delivers medication right next to the nerve that is causing your pain. Besides easing pain, it can also help show which nerve is the source.
What You'll Learn
What a nerve block is, and how it differs from pills
Its two uses: to relieve and to check
The types of injection used for spinal stenosis
What happens on the day, and what to tell your doctor first
What is known about benefit, steroids, and safety
Your next step if it works, and if it doesn't
In clinic, people often tell me, "A needle next to my spine sounds scary," or ask, "Once I start, will I need these shots forever?" This page separates what a nerve block can do from what it cannot.
1. What a Nerve Block Is: Two Uses
Delivering medication next to the nerve
A nerve block places a local anesthetic (a numbing medication) right next to the nerve that is causing your pain or numbness. Sometimes an anti-inflammatory medication (a steroid) is added.
A pill travels through the bloodstream to the whole body. A nerve block leaves the medication where the troubled nerve is.
The first thing to know: the injection does not change the narrowing of the spinal canal itself. A nerve block calms the nerve and eases pain. It does not cure the condition.
To relieve, and to check
A nerve block has two uses.
The first is to relieve: to calm the pain and make daily life easier. Pain specialists (pain clinics) sometimes repeat blocks at intervals for this purpose.
The second is to check. With spinal stenosis, an MRI often shows narrowing in several places. The images alone cannot tell which one is causing your leg pain now. So the doctor injects one suspect nerve and sees whether your usual pain goes away.
I rarely use blocks as treatment; for us they're mainly a way to find the nerve root causing the greatest pain when imaging raises the possibility of multiple nerve root involvement.
Even as a test, a block is not perfect. If the medication spreads to a neighboring nerve, or does not reach the target, the result can be misleading.[1][2] The result is one clue, read together with your examination and MRI.
Where the guidelines stand
The Japanese clinical practice guideline for lumbar spinal stenosis (2021) includes nerve blocks among the conservative (non-surgical) treatment options.[3]
2. Types of Injection Used for Stenosis
Nerve blocks are named by where the injection goes. Which one is chosen depends on whether symptoms are in one leg or both, where the narrowing is, and the purpose. Whether one type works clearly better than another is not yet known.[4]
From just above the buttocks: caudal epidural block
The injection goes through a small opening in the sacrum, just above the buttocks. Think of it as pouring medication in through the lower entrance of the spinal canal.
Easy to do as an outpatient
Reaches symptoms in both legs well
Between the vertebrae in the lower back: interlaminar epidural block
The injection goes into the gap between two vertebrae in the middle of the lower back, close to the narrowed area, and the medication enters the spinal canal.
At the nerve exit: selective nerve root block
The doctor targets one nerve root (a nerve leaving the spine toward the leg) while watching on X-ray. This is the type mainly used to check.
As the needle nears the nerve, your usual leg pain may flash for a moment. That too is a clue that this nerve is involved
If the nerve exit is severely narrowed, the medication may not reach it well
At the small spinal joints: facet joint block
The injection goes around the small joints that link the vertebrae (facet joints). It is used mainly for pain in the lower back itself and is less suited to leg numbness.
3. The Day of the Injection, and What to Tell Your Doctor First
On the day
Details vary by clinic, but the general flow is:
At the visit, confirm which type of injection you will have, and why
Lie face down or on your side on the exam table
The skin is cleaned and a thin needle is used. It usually takes only a few minutes
Afterward, rest for a while before leaving
Go home after checking that your legs have their strength
In my clinic, patients rest for about 10 minutes after the injection. Then a staff member walks with them to check that their legs are strong before they go home. While the local anesthetic is working, your legs may feel numb or weak.[5]
Two things to tell your doctor beforehand
If you take a blood thinner, tell your doctor before the injection. How bleeding risk is managed depends on the type of injection.[6] Do not stop the medicine on your own; stopping can interrupt protection against heart attack or stroke. Ask first.
If you have diabetes, tell your doctor as well. A steroid can raise your blood sugar for a short time after the injection, usually settling within a few days.[7] If you check your own blood sugar, watch it more closely for a few days.
When to call after the injection
Contact the clinic where you had the injection if:
Numbness or weakness in your legs has not worn off by the end of the day
The injection site becomes red and swollen, or you develop a fever
A strong headache persists that eases when you lie down
4. Benefit and Safety: What Is Known
How well it works
Many people feel their pain or numbness ease after a nerve block. But relief is often short-lived, and research has not shown a lasting benefit.[8][9]
Results vary a great deal from person to person. People with more severe narrowing tend to feel less benefit.[4][10]
So the best way to use a nerve block is to walk and move while the pain is lower. Treat the injection as a "bridge" to starting exercise. See Exercise Therapy for how to get started.
About adding a steroid
A steroid (an anti-inflammatory medication) is sometimes added. In spinal stenosis, though, many studies found little difference compared with local anesthetic alone.[11][12][9]
Steroids also have short-term effects on the body's hormones and on blood sugar.[13][7] Whether to use one, and how much, is decided with your doctor.
Safety
Most side effects are temporary.
Common: temporary leg numbness or weakness, tiredness, light-headedness. These wear off with time[5][14]
Uncommon: infection, bleeding, headache (from a leak of the fluid around the spinal nerves)[15]
Very rare: serious nerve complications. Most reports involve injections in the neck, or particular types of steroid[15][16]
Age alone does not rule out a block. Other conditions and medications change the decision, so discuss it with your doctor.
What if I have surgery after injections?
One study abroad found that people with spinal stenosis who had epidural steroid injections improved less over time.[17] But the groups compared were different; for example, those who had injections were more likely to want to avoid surgery from the start. Whether the injections themselves caused the difference is unknown.
5. If It Works, If It Doesn't: Your Next Step
If it worked
That nerve is likely the source of your current pain. Move while the pain is lower. If you need another shot every time the effect wears off, it may be time to discuss further treatment.
If it didn't work
This is useful information too. The pain may come from somewhere else, or the narrowing may be severe. Use the result to review the examination and the images.
One study found that how much a nerve root block eased leg pain was related to how much leg pain improved after surgery, but not to daily function after surgery.[18]
When to consider other treatment
If medication and injections have not brought back your walking distance or your daily life, it is time to discuss surgery with your doctor.[8] Besides surgery, you may also hear about spinal cord stimulation (SCS). Note: SCS availability and insurance coverage vary by country and provider; ask your doctor whether this option is accessible to you. Which treatment suits you is a decision to make with your doctor.
If your legs suddenly become weak, or you have trouble passing urine or stool, see a doctor right away without waiting for a scheduled injection.
Questions to ask your doctor
"Is this injection to relieve the pain, or to find the cause?"
"Which type of injection is this, in my case?"
"What happens next if it works, and if it doesn't?"
"Will you use a steroid?"
"Can I start exercising after the injection?"
Knowing the answer to the first question changes how you read the result.
Frequently asked questions
Q. How many times can I have one?
Very few studies give a set number. Your doctor will decide with you based on how long the effect lasts and how much easier daily life becomes. If you keep needing a shot every time the effect wears off, it may be time to consider other treatment.
Q. Will the injection let me avoid surgery?
No one can promise that. In a study abroad of people with nerve root pain who were considering surgery, some decided against surgery after injections.[19][20] Who will benefit this way is not yet known.
Q. Does it hurt? Can I get hooked on it?
There is a brief sting from the needle, and the injection is usually over in minutes. The medication is a local anesthetic, not a narcotic, so you do not build up a need for more.
Summary
A nerve block delivers medication next to the nerve. It does not change the narrowing itself
It has two uses: to relieve and to check. A "check" result is one clue, read together with the examination and MRI
Before the injection, tell your doctor about blood thinners and diabetes
Relief is often short-lived. Use it as a bridge to moving more
Whether it works or not, the result helps decide your next treatment
This page provides general information. Whether to have a nerve block, and which type, is a decision to make with your doctor.
Yeom JS, Lee JW, Park KW, et al. Value of diagnostic lumbar selective nerve root block: a prospective controlled study. *AJNR Am J Neuroradiol*. 2008;29(5):1017-23. PMID: 18272560 — diagnostic accuracy of nerve root blocks was moderate; overflow or poor spread of the injectate caused false results (prospective study, 47 patients)
Beynon R, Elwenspoek MMC, Sheppard A, et al. The utility of diagnostic selective nerve root blocks in the management of patients with lumbar radiculopathy: a systematic review. *BMJ Open*. 2019;9(4):e025790. PMID: 31005925 — diagnostic accuracy is uncertain, and specificity in particular may be low (systematic review of 6 studies, all at high risk of bias)
Japanese Orthopaedic Association / Japanese Society for Spine Surgery and Related Research (eds). *Clinical Practice Guideline for Lumbar Spinal Stenosis 2021* (2nd ed). Nankodo, 2021. English secondary publication: Kawakami M, Takeshita K, Inoue G, et al. *J Orthop Sci*. 2023;28(1):46-91. PMID: 35597732 — includes nerve blocks among conservative options (Japanese clinical guideline)
Wilderman I, Sarzetto F, Didari T, et al. Safety and Effectiveness of Different Approaches for Epidural Steroid Injections in Lumbar Spinal Stenosis: A Systematic Review and Meta-Analysis. *Pain Physician*. 2026;29(5):E337-E361. PMID: 42550520 — no clear difference by route (caudal, interlaminar, transforaminal); weaker relief with severe stenosis (meta-analysis of 24 studies; mostly small, heterogeneous)
Stalcup ST, Crall TS, Gilula L, et al. Influence of needle-tip position on the incidence of immediate complications in 2,217 selective lumbar nerve root blocks. *Spine J*. 2006;6(2):170-6. PMID: 16517389 — immediate complications after fluoroscopy-guided nerve root blocks were minor and transient, such as weakness or light-headedness (retrospective study)
Narouze S, Benzon HT, Provenzano D, et al. Interventional Spine and Pain Procedures in Patients on Antiplatelet and Anticoagulant Medications (Second Edition). *Reg Anesth Pain Med*. 2018;43(3):225-262. PMID: 29278603 — management of blood thinners depends on the bleeding risk of the procedure (multisociety guideline)
Even JL, Crosby CG, Song Y, et al. Effects of epidural steroid injections on blood glucose levels in patients with diabetes mellitus. *Spine (Phila Pa 1976)*. 2012;37(1):E46-50. PMID: 21540770 — blood sugar rose after injection in people with diabetes and returned to range in about 2 days (prospective cohort, 30 patients)
Katz JN, Zimmerman ZE, Mass H, et al. Diagnosis and Management of Lumbar Spinal Stenosis: A Review. *JAMA*. 2022;327(17):1688-1699. PMID: 35503342 — long-term benefit of epidural steroid injections has not been shown; decompression is an option when pain and activity limits persist despite conservative care (review)
Ammendolia C, Hofkirchner C, Plener J, et al. Non-operative treatment for lumbar spinal stenosis with neurogenic claudication: an updated systematic review. *BMJ Open*. 2022;12(1):e057724. PMID: 35046008 — added benefit of epidural steroids is small even in the short term; exercise with manual therapy is effective (systematic review of randomized trials, moderate quality)
Sakai M, Inokuchi A, Imamura R, et al. Efficacy of Nerve Root Block for the Treatment of Lumbar Spinal Canal Stenosis in Adults Older Than 80 Years of Age. *Cureus*. 2022;14(5):e24863. PMID: 35702474 — nerve root blocks in 112 patients over 80; those without benefit had narrower canals; no severe neuralgia (single-center retrospective study, Japan)
Friedly JL, Comstock BA, Turner JA, et al. A randomized trial of epidural glucocorticoid injections for spinal stenosis. *N Engl J Med*. 2014;371(1):11-21. PMID: 24988555 — in 400 patients, steroid plus anesthetic vs anesthetic alone showed no difference in pain or function at 6 weeks (randomized controlled trial)
Meng H, Fei Q, Wang B, et al. Epidural injections with or without steroids in managing chronic low back pain secondary to lumbar spinal stenosis: a meta-analysis of 13 randomized controlled trials. *Drug Des Devel Ther*. 2015;9:4657-67. PMID: 26316704 — adding a steroid gave no extra improvement (meta-analysis of 13 randomized trials)
Friedly JL, Comstock BA, Heagerty PJ, et al. Systemic effects of epidural steroid injections for spinal stenosis. *Pain*. 2018;159(5):876-883. PMID: 29394207 — cortisol suppression at 3 weeks was more common after steroid injections than after anesthetic alone (secondary analysis of a randomized trial)
Beynon R, Hawkins J, Laing R, et al. The diagnostic utility and cost-effectiveness of selective nerve root blocks in patients considered for lumbar decompression surgery: a systematic review and economic model. *Health Technol Assess*. 2013;17(19):1-88. PMID: 23673151 — no major or permanent complications reported; minor complications were uncommon (systematic review)
Manchikanti L, Benyamin RM. Key safety considerations when administering epidural steroid injections. *Pain Manag*. 2015;5(4):261-72. PMID: 26059467 — complications of epidural injections and prevention; most serious neurological events involved cervical transforaminal injections (review)
Cohen SP, Greuber E, Vought K, et al. Safety of Epidural Steroid Injections for Lumbosacral Radicular Pain: Unmet Medical Need. *Clin J Pain*. 2021;37(9):707-717. PMID: 34265792 — serious neurological complications are rare and more often linked to particulate steroids given transforaminally (review; authors include pharmaceutical company employees)
Radcliff K, Kepler C, Hilibrand A, et al. Epidural steroid injections are associated with less improvement in patients with lumbar spinal stenosis: a subgroup analysis of the Spine Patient Outcomes Research Trial. *Spine (Phila Pa 1976)*. 2013;38(4):279-91. PMID: 23238485 — patients who had epidural steroid injections improved less over 4 years (observational subgroup analysis; injected patients more often preferred to avoid surgery)
Ko S, Jun C, Min WK, et al. Pain Relief After Selective Nerve Root Block as a Predictor of Postoperative Functional Outcome in Patients with Degenerative Lumbar Spinal Stenosis Patients Undergoing Decompressive Surgery. *Spine (Phila Pa 1976)*. 2022;47(9):666-671. PMID: 34468438 — relief after a nerve root block was associated with leg pain improvement 12 months after surgery but not with function (60 patients, level of evidence 4)
Riew KD, Yin Y, Gilula L, et al. The effect of nerve-root injections on the need for operative treatment of lumbar radicular pain. A prospective, randomized, controlled, double-blind study. *J Bone Joint Surg Am*. 2000;82(11):1589-93. PMID: 11097449 — some of 55 surgical candidates with nerve root pain chose not to have surgery after injections (randomized trial; not limited to stenosis)
Riew KD, Park JB, Cho YS, et al. Nerve root blocks in the treatment of lumbar radicular pain. A minimum five-year follow-up. *J Bone Joint Surg Am*. 2006;88(8):1722-5. PMID: 16882893 — most who avoided surgery in the study above still had not had surgery at 5 years (follow-up)
