A lumbar epidural is an injection delivered into a small space in your lower back, just outside the membrane that surrounds your spinal cord. The goal is to place medication, typically a steroid combined with a numbing agent, directly near the irritated spinal nerves causing your pain. It’s one of the most common procedures for managing lower back and leg pain that hasn’t responded to more conservative treatments.
Where the Needle Goes
Your spine has a natural gap called the epidural space. It sits between the bony walls of your spinal canal and the tough membrane (the dura) that wraps around your spinal cord and its fluid. This space contains a thin layer of connective tissue, a network of small veins, and a pad of fat that cushions the nerves branching off your spinal cord. In the lumbar region, your lower back, this space is relatively easy to access because the gaps between vertebrae are wider than in other parts of the spine.
The medication doesn’t go into the spinal fluid itself. It stays in that outer space, bathing the nerve roots as they exit the spinal cord. This is the key distinction between an epidural and a spinal block: a spinal block delivers medication directly into the fluid surrounding the spinal cord and takes effect almost immediately, while an epidural delivers it outside that fluid layer and typically takes 10 to 20 minutes to begin working.
Why It’s Done
Lumbar epidurals are used in two broad contexts. The first, and what most people searching this term are facing, is a steroid injection to treat chronic or acute pain. Herniated discs, spinal stenosis (narrowing of the spinal canal), and radiculopathy (pain radiating down a leg from a pinched nerve) are the most common reasons. When a disc bulges or bone spurs press on a nerve root, the surrounding tissue becomes inflamed. The steroid reduces that inflammation, and the numbing agent provides short-term relief while the steroid kicks in.
The second context is labor and delivery. An epidural catheter placed in the lumbar region delivers continuous numbing medication to block pain signals from the uterus and birth canal. Though the anatomy is the same, the medications and goals differ, so most of what follows focuses on the steroid injection version.
What Happens During the Procedure
You’ll typically lie face down on a table, though some providers have you sit up and curl forward. The doctor uses fluoroscopy, a real-time X-ray, to identify the exact space between two vertebrae in your lower back. After cleaning and numbing the skin, they advance a needle through several layers: skin, the tissue beneath it, a ligament connecting the vertebrae, and finally a thick, rubbery ligament called the ligamentum flavum.
The doctor knows the needle has reached the epidural space using a technique called loss of resistance. They attach a small syringe with a tiny amount of air or saline to the needle and apply gentle, steady pressure as they advance. The ligamentum flavum is dense enough to resist that pressure. The moment the needle tip passes through it into the epidural space, the resistance suddenly drops and the syringe plunges easily. It’s a tactile signal that tells the doctor they’re in the right spot without going too deep.
Once positioned, contrast dye is often injected under X-ray to confirm placement. Then the medication goes in. The entire procedure usually takes 15 to 30 minutes.
What Relief Looks Like
The numbing agent can provide some immediate relief, but that wears off within hours. The steroid component typically begins working within one to three days, though in some cases it takes up to a week. Many people experience several months of meaningful pain reduction and improved function. For others, the relief is shorter-lived, lasting weeks rather than months. Results vary depending on the underlying condition, how long you’ve had symptoms, and how much inflammation is present.
If a single injection provides partial but incomplete relief, your doctor may recommend a series of up to three injections spaced several weeks apart. These aren’t meant to be a permanent fix. The goal is often to create a window of reduced pain so you can participate more effectively in physical therapy and rehabilitation, addressing the root cause rather than just the symptom.
Risks and Complications
The most common side effects are mild: temporary soreness at the injection site, a brief increase in pain, and occasionally a slight rise in blood sugar for people with diabetes (steroids can do this). Some people feel flushed or have trouble sleeping for a night or two after the injection.
The more significant risk is accidental dural puncture, where the needle goes slightly too deep and pierces the membrane containing spinal fluid. This can cause a positional headache, one that worsens when you sit or stand and improves when you lie flat. In one study of 285 consecutive procedures involving dural puncture, about 30% of patients developed this type of headache. It typically appeared within two days and resolved on its own within two to three days on average. People with a lower body mass index appear more susceptible.
Serious complications are rare. In a review of more than 8,000 epidural procedures at a single hospital, bleeding that compressed the spinal cord (epidural hematoma) occurred in roughly 1 in 4,100 cases, and infection in the epidural space (epidural abscess) occurred in about 1 in 1,400. The combined rate was about 0.1%. Only one patient in that entire series required surgery to address the complication, and none had lasting neurological damage.
Who Should Not Have One
Blood-thinning medications are the biggest concern. If you take warfarin, your clotting levels need to be checked and normalized before the procedure. For patients who stop warfarin five to six days beforehand, doctors look for specific blood test results confirming clotting has returned to near-normal levels. Newer blood thinners that target clotting factors carry a specific warning about the risk of epidural bleeding, and your doctor will give you a timeline for when to stop and restart them.
Several factors increase the risk of bleeding complications: age over 65, kidney problems, abnormalities in the spine, and taking multiple medications that affect clotting (like combining a blood thinner with anti-inflammatory drugs). Active infection at the injection site or a systemic blood infection also rules out the procedure, since introducing a needle could seed bacteria into the epidural space.
What to Expect Afterward
You’ll be monitored for 15 to 30 minutes after the injection, primarily to watch for any allergic reaction or unusual numbness. Most people go home the same day and can return to light activities within 24 hours. You may be told to avoid driving for the rest of the day, especially if your legs feel slightly heavy or numb from the local anesthetic.
It’s common to feel increased soreness at the injection site for a day or two. Applying ice for 15 to 20 minutes at a time can help. The real test of whether the injection worked comes in the days that follow, as the steroid takes effect and the inflammation around the nerve root begins to subside.