Side Effects and Risks of Epidural Steroid Injections
Epidural steroid injections carry a small risk of moderate complications (8.6% prolonged pain, 2.1% altered consciousness, 1.4% dural puncture, 0.7% deep infection) and a very small but catastrophic risk of paralysis, stroke, spinal cord infarction, and death. 1
Moderate to Serious Adverse Events (Small Risk)
The most recent 2025 BMJ guideline identifies the following moderate harms based on systematic review evidence 1:
- Prolonged pain or stiffness (>48 hours): 8.6% risk
- Temporary altered level of consciousness: 2.1% risk
- Dural puncture: 1.4% risk
- Deep infection: 0.7% risk
- Infection progressing to meningitis: Very rare but documented
Catastrophic Complications (Very Small Risk)
Between 1997 and 2014, the FDA Adverse Event Reporting System captured 90 serious adverse events occurring within minutes to 48 hours after epidural corticosteroid injections 1. These catastrophic events include:
- Death
- Spinal cord infarction
- Paraplegia and quadriplegia
- Cortical blindness
- Stroke (affecting cord, brainstem, and cerebellum)
- Seizures
- Brain edema
Risk Varies by Injection Location
The 2021 Medicare population study found significantly higher risk with cervical/thoracic injections compared to lumbar/sacral injections 2:
- Cervical/thoracic ESI: 29.4 serious spinal adverse events per 1,000 patients
- Lumbar/sacral ESI: 5.1 per 1,000 patients
- Lumbar/sacral non-transforaminal: 8.8 per 1,000 patients
This represents a nearly 6-fold higher risk for cervical/thoracic injections (p=0.001) 2.
Particulate vs Non-Particulate Steroids
Particulate corticosteroids (like methylprednisolone) carry higher risk of embolic complications when inadvertently injected intra-arterially, particularly with transforaminal approaches 3, 4. The particulate matter can embolize into distal arterial branches, causing strokes to the spinal cord, brainstem, and cerebellum 5. However, the overall event rates between particulate (7.5 per million) and non-particulate formulations (13.1 per million) showed no statistical difference in the Medicare study 2.
Common Minor Adverse Events
The most frequent side effects are relatively minor and self-limited 4, 6:
- Procedural-related pain
- Steroid-related side effects: elevated blood glucose, adrenal suppression
- Vasovagal reactions
- Incidence of minor events: Generally less than 1% 6
Systemic Steroid Effects
When corticosteroids are absorbed systemically from epidural injections, patients may experience:
- Elevated blood glucose (particularly important for diabetic patients)
- Adrenal suppression
- Reduction in bone mineral density with repeated injections
- Increased risk of postoperative joint infection if surgery follows soon after injection 7
Critical Context: Risk-Benefit Ratio
The 2025 BMJ guideline strongly recommends AGAINST epidural steroid injections for chronic axial spine pain and chronic radicular spine pain because moderate certainty evidence shows little to no pain relief compared to sham procedures, while the procedures carry documented risks and burden 1. The guideline panel concluded that patients would be disinclined to receive treatment with very low certainty of benefit but moderate to high certainty evidence of harm 1.
Important Caveat
The FDA has not approved corticosteroid injections into the epidural space, and issued a safety warning in 2014 regarding the risk of serious neurological complications 3, 5. Many of these procedures are performed despite lack of FDA approval and no documented long-term efficacy 5.
Practical Considerations
- Reporting bias: Only approximately half of randomized trials report adverse events, suggesting actual complication rates may be underestimated 1
- Medicolegal cases: Additional adverse events are increasingly found in medicolegal literature, suggesting underreporting in medical literature 5
- Timing of complications: Most serious events occur within minutes to 48 hours after injection 1
- Insurance-mandated delays: Some insurance carriers require these injections before approving definitive surgery, potentially delaying necessary operative intervention while exposing patients to procedural risks 5