As with any injection procedure, potential side effects and risks are possible with lumbar epidural steroid injections. The side effects are usually temporary and tolerable. Rarely, serious adverse events may occur.1
The most common risk is that the injection does not provide any, or only provides minimal, pain relief. It is disappointing to go through the procedure and not experience a meaningful reduction in pain, or to find that the initial pain relief is fleeting, and the original pain returns after a few weeks.
Possible Side Effects of Epidural Steroid Injections
- Fainting due to anxiety from the procedure causing a sudden decrease in heart rate and blood pressure (vasovagal attack)
- Flushing of the face (redness and a feeling of warmth)
These side effects typically resolve with rest. Injection site pain, if present, may be treated with cold therapy using ice packs to reduce pain and/or swelling.
Potential Complications and Adverse Events after an Epidural Steroid Injection
While rare, serious complications are possible after an epidural steroid injection and are discussed below.
Infections may occur generally within the body (systemic infection), affect the brain and/or spinal cord, or occur locally in the area of the injection. Examples include4:
- Epidural abscess: Accumulation of pus in the epidural space.
- Meningitis: Inflammation of the brain and spinal cord membranes.
- Osteomyelitis or discitis: Infection of the vertebral bone or disc.
- Soft tissue abscess: Accumulation of pus within the soft tissues at the site of injection.
Microbes from the patient’s skin are believed to be a common cause of infections.1
Damage to arteries may cause localized bleeding and pooling of blood within the soft tissues, epidural space, or membranes of the spinal cord. A hematoma or blood clot may form within the artery, blocking the blood supply to vital tissues, such as the brain and/or spinal cord.4
Inadvertently inserting the needle into the spinal cord’s outer membrane (dura mater) may cause a dural puncture.4 This condition is also called a wet tap and causes the cerebrospinal fluid (CSF) to leak out, decreasing CSF pressure in the brain, resulting in a headache.
Damage to neighboring nerves may cause abnormal sensations, loss of sensation, or seizures. If the cauda equina nerves are damaged at the base of the spinal cord, it may result in a medical emergency called cauda equina syndrome. This syndrome causes loss of bowel and bladder control and must be treated immediately to prevent paralysis of the lower body.4
Cardiovascular system (heart) complications
Sometimes, low blood pressure and decreased heart rate may occur after an epidural steroid injection.4
Risk associated with local anesthetics
In injections containing local anesthetics, if the solution enters a blood vessel, it may result in toxicity of the central nervous system and/or the cardiovascular system.5
Risk associated with particulate steroids
Risks and complications are typically higher in epidural steroid injections administered above the L3 level.3,8 The most common risk is the injection of steroids into a blood vessel, which becomes more likely to occur in people over 50 years of age.7 Rarely, an allergic reaction to the steroids, local anesthetic, or contrast dye may occur.
When to Call a Doctor
Serious symptoms following an epidural steroid injection that require immediate medical attention include:
- Severe headache while sitting up or standing that feels better after lying down, which may indicate a dural puncture
- A fever of 101 degrees or greater, which may indicate an infection
- Reduced or complete loss of bowel or bladder control while the patient is still numb or after the local anesthetic and temporary numbness wear off, which may indicate medical emergencies, such as cauda equina syndrome
- A feeling of numbness and/or weakness in the leg(s), which may indicate nerve injury
It is important to call the doctor immediately if these symptoms occur. Additionally, any discomfort or abnormal feeling must be discussed with the doctor.