Epidural steroid injections (ESIs) are a frequent treatment option for managing pain that originates in the spine and radiates into the limbs. The procedure involves delivering a corticosteroid medication, a potent anti-inflammatory agent, directly into the epidural space surrounding the spinal cord and nerve roots. This targeted delivery is intended to reduce inflammation and swelling around irritated spinal nerves, which are often compressed by conditions like herniated discs or sciatica. By reducing this irritation, ESIs aim to alleviate the radiating pain, numbness, or tingling. The primary goal is to provide enough pain relief to allow patients to participate more effectively in physical therapy.
Immediate Post-Procedure Tenderness
A temporary increase in localized discomfort is common immediately following the injection, usually within the first 12 hours. This initial soreness is mechanical, resulting from the physical act of the procedure, as the needle insertion causes minor trauma to surrounding tissues. The volume of the injected fluid also temporarily increases pressure in the epidural space, which can momentarily irritate inflamed nerves. Additionally, as the short-lived local anesthetic wears off, the underlying nerve pain may briefly return before the steroid takes effect. This expected soreness is typically mild and resolves within a day or two.
Understanding the Steroid Flare Reaction
A distinct type of pain increase, known as a “steroid flare,” can occur hours or days after the procedure, typically between 12 hours and three days post-injection. This reaction is a transient chemical irritation separate from the immediate mechanical soreness. The corticosteroid is often prepared as a crystalline suspension, and when these microscopic particles are deposited, they can temporarily trigger a localized inflammatory response. This irritation causes a temporary worsening of pain and swelling, and sometimes the original radiating nerve pain may increase. A steroid flare is a known, self-limiting side effect that typically resolves within 48 to 72 hours as the steroid begins its powerful anti-inflammatory action.
Serious Complications That Increase Pain
While immediate tenderness and steroid flares are common and temporary, a severe, escalating, or entirely new type of pain can signal a rare but serious medical complication requiring immediate attention.
Infections
Infections, such as an epidural abscess or meningitis, are characterized by rapidly escalating, unremitting back pain, often accompanied by systemic symptoms like fever and chills.
Hematoma and Nerve Injury
A hematoma, or collection of blood near the spinal cord, can cause severe, sharp back pain and new neurological deficits if pressure on the nerves is significant. New onset of severe neurological symptoms, such as numbness, weakness, or electric shock-like pain, may indicate nerve injury or irritation. This occurs if the needle trajectory or the injected material affects a nerve bundle.
Dural Puncture
A severe headache that worsens dramatically when sitting or standing and improves when lying down may indicate a dural puncture. This happens when the needle inadvertently pierces the membrane surrounding the spinal cord, causing a cerebrospinal fluid leak.
When to Contact Your Physician
It is important to understand the difference between expected discomfort and symptoms that require medical evaluation. Mild soreness lasting less than 12 hours or a steroid flare resolving within three days is generally tolerable.
You should contact your healthcare provider immediately if you experience severe pain that does not improve after 72 hours or is rapidly escalating. Red flag symptoms warranting an urgent call include:
- The onset of a high fever or chills, which can suggest an infection.
- New or worsening neurological changes, such as numbness or weakness in the legs.
- Any loss of bowel or bladder control.
- A severe headache that is noticeably worse when upright.