An epidural is an injection of pain-relieving medication into a small space in your spine called the epidural space. It blocks pain signals from traveling through the nerves in that area, numbing part of your body while you stay awake and alert. Most people associate epidurals with childbirth, but they’re also used during surgeries, after operations, and to manage chronic back pain.
Where the Medication Goes
Your spinal cord sits inside a protective sac called the dural sac. Surrounding that sac is a narrow space filled with fat, blood vessels, connective tissue, and the roots of spinal nerves. That’s the epidural space. It runs the length of your spine, from the base of your skull down to your tailbone. The back wall of this space is formed by a tough ligament called the ligamentum flavum, which is the last layer a needle passes through to reach it.
When medication is delivered into this space, it bathes the nerve roots that branch off from the spinal cord. Those nerve roots carry pain signals from specific parts of your body, so numbing them at the source can block pain in the chest, abdomen, pelvis, or legs depending on where along the spine the injection is placed.
Types of Epidurals
There are two main categories, and they serve very different purposes.
Epidural anesthesia uses a numbing agent (a local anesthetic), sometimes combined with a low-dose pain reliever, to block sensation. This is the type used during labor and for surgical pain control. A thin catheter is typically left in place so medication can be delivered continuously or topped up as needed over hours or even days.
Epidural steroid injections are a one-time shot of an anti-inflammatory steroid into the epidural space. These target chronic pain and inflammation from conditions like herniated discs or spinal stenosis. Research shows that both steroid injections and local anesthetic injections alone provide significant pain relief and improved function for chronic low back pain from spinal stenosis. Interestingly, adding a steroid doesn’t appear to offer a major advantage over local anesthetic alone for that condition, though it may extend the duration of relief.
Common Reasons for an Epidural
- Labor pain relief: The most well-known use. An epidural can reduce or eliminate pain from contractions while still allowing you to feel pressure and push.
- Surgical anesthesia: Used as the primary form of pain control for certain surgeries, particularly those involving the lower body.
- Post-surgical pain management: A catheter left in place after an operation delivers steady pain relief during recovery, reducing the need for other pain medications.
- Chronic pain: Epidural steroid injections can help manage ongoing back or leg pain caused by disc problems, nerve compression, or spinal narrowing.
What the Procedure Feels Like
You’ll either sit upright and curl forward or lie on your side in a curled position. Both postures open up the spaces between your vertebrae, giving the provider a better target. The skin on your back is cleaned, and a small area is numbed with a local anesthetic, which feels like a brief sting.
A specialized hollow needle is then guided between two vertebrae toward the epidural space. Providers locate the space using a technique called “loss of resistance,” where they gently push on a syringe attached to the needle. When the needle tip passes through the ligamentum flavum and enters the epidural space, there’s a sudden ease in the resistance they feel. The whole insertion typically takes just a few minutes, though it can take longer if positioning is tricky.
For labor or surgical epidurals, a soft, flexible catheter is threaded through the needle and left in place. The needle is then removed, and the catheter is taped securely to your back. Medication flows through this catheter for as long as it’s needed. For steroid injections, there’s no catheter. The medication is injected in a single dose and the needle is withdrawn.
How Quickly It Works and Wears Off
A labor epidural typically begins reducing pain within 10 to 20 minutes of the first dose. You’ll likely feel warmth or tingling in your legs first, followed by a progressive loss of sharp pain sensation. Most people retain some sense of pressure and can still move their legs to some degree, though they feel heavy.
Once the medication is stopped (after delivery or after surgery), sensation and motor function gradually return. The numbing effects generally wear off within a few hours. For epidural steroid injections, the numbing component fades within hours, but the anti-inflammatory effect of the steroid builds over several days and can last weeks to months.
Common Side Effects
Blood pressure drops are the most frequent side effect of labor epidurals. In one study of 439 women receiving epidurals during labor, 36% experienced a significant drop in blood pressure. This happens because the same nerves that carry pain signals also help regulate blood vessel tone. When they’re blocked, blood vessels relax and widen, lowering pressure. Medical teams monitor this closely and can treat it quickly with fluids or medication.
Other common side effects include shivering (even when you’re not cold), itching (a reaction to the pain-relieving component of the medication), and temporary difficulty urinating. A urinary catheter is often placed because you may not feel the urge to go. Some people also experience a feeling of heaviness or weakness in the legs that resolves once the epidural wears off.
Rare but Serious Risks
The most talked-about rare complication is a post-dural puncture headache. This happens if the needle accidentally pierces the dural sac, allowing spinal fluid to leak. The resulting headache is distinctly positional: it gets worse when you sit or stand up and improves when you lie flat. It’s often accompanied by neck stiffness, sensitivity to light, nausea, or changes in hearing. Most of these headaches resolve on their own within a week or two, though a procedure called a blood patch (where a small amount of your own blood is injected into the epidural space to seal the leak) can provide faster relief.
Other rare risks include infection at the injection site, nerve damage (usually temporary tingling or numbness), and, very rarely, bleeding in the epidural space that could compress nerves. Permanent complications are extremely uncommon.
When an Epidural May Not Work
Epidurals don’t provide perfect pain relief for everyone. Studies in surgical settings have found that a substantial number of patients, roughly a third or more, experience some degree of inadequate pain control from an epidural and need supplemental pain medication. In labor, incomplete coverage can mean pain persists on one side of the body, or in a specific area like the lower pelvis. When this happens, the catheter position can sometimes be adjusted, the medication dose increased, or, if necessary, the epidural replaced entirely.
Factors that can affect how well an epidural works include body composition, the curvature of the spine, how quickly labor is progressing, and the exact position of the catheter tip in the epidural space. A catheter that migrates even slightly can change the quality of pain relief.