An epidural steroid injection can ease leg pain from a trapped nerve, but for most people the effect is SMALL and SHORT-LIVED. When it helps, relief usually lasts weeks to a few months, and rarely up to a year.
It works best for leg pain from a slipped disc, known as sciatica. It helps less for back pain on its own, and for narrowing of the spine the steroid seems to add little.
Its real job is to buy you a window of lower pain, so you can move and exercise while the nerve settles.
What an epidural steroid injection is
- Steroid plus numbing medicine. The injection usually contains a corticosteroid, which calms inflammation, and a local anesthetic, which numbs
- Into the space around the nerves. The epidural space surrounds the spinal nerves. The doctor uses X-ray guidance to place the medicine near the irritated nerve
- Three ways in: from the back between two bones, from the side where a nerve leaves the spine, or through an opening near the tailbone. Your doctor chooses based on where the problem is
- You’re awake. It’s done as an outpatient, and the skin is numbed first. Most people go home the same day and take it easy for the rest of it
- It’s not a labor epidural. That’s a continuous numbing drip for childbirth. This is a single injection
How long does it take to work, and how long does it last?
- The first few hours: the numbing medicine may ease pain straight away, then wear off. Your leg may feel heavy or numb for a while
- Days 1 to 3: pain can get WORSE before it gets better. This is common and settles
- Days 2 to 7: the steroid starts to work, if it’s going to
- After that: relief lasts anywhere from weeks to months. Some people get no relief at all
What the evidence says
- For sciatica: trials comparing epidurals with fake injections find a small drop in leg pain for up to about 3 months. For many people the difference is too small to notice much
- In the long run: by a year, people who had the injection are no better off than those who didn’t
- Avoiding surgery: the evidence doesn’t show that it clearly lowers your chance of needing an operation
- For spinal stenosis: in a large trial, adding steroid worked no better than an injection of numbing medicine alone. See spinal stenosis
- For back pain without leg pain: there’s little good evidence that it helps
An epidural doesn’t fix the disc. At best it turns the volume down while your body does.
When it’s worth considering
- Leg pain is severe and stopping you sleeping, walking or working
- Painkillers and exercise aren’t enough to keep you moving while the disc settles. See how long a slipped disc takes to heal
- You’d like to avoid or delay surgery and you accept the benefit may be modest and short
- You’ll use the window. If the pain eases, that’s the time to build up walking and exercise with your physio, not to rest
Side effects
Common ones are mild and pass within a few days:
- A pain flare for 2 to 3 days
- Soreness or bruising where the needle went in
- A flushed face or trouble sleeping for a few days
- Higher blood sugar for a few days if you have diabetes. Check it more often
- Raised eye pressure for a short time if you have glaucoma
Rare but serious risks include a severe headache from leaking spinal fluid, infection, bleeding around the nerves, nerve damage and, very rarely, paralysis. Because steroid effects add up, most doctors limit epidurals to about 2 to 3 a year.
See cortisone shot side effects.
Go to the emergency department now if
After an injection or at any time, these can mean cauda equina syndrome, bleeding or infection pressing on the nerves at the bottom of the spine. They’re rare, but they need hospital care the same day.
- New trouble peeing, not being able to pee, or leaking pee or poo without knowing
- Numbness around your genitals, buttocks or inner thighs, the area that would touch a saddle
- New weakness or numbness in BOTH legs
- Fever with severe back pain in the days after the injection
- A severe headache with a stiff neck or fever
Call the doctor who did the injection if
- You have a headache that’s worse when you sit or stand and eases when you lie flat
- The injection site is red, warm or leaking
- Your blood sugar stays high for more than a few days
- A week later, your leg pain is clearly worse than it was before the injection
An epidural can quiet the pain for a while. What you do in that quiet is what counts.