This information is for people who have a slipped disc. It tells you about steroids injected into the spine, a treatment used for a slipped disc. It is based on the best and most up-to-date research.
Do they work?
Probably not. Having a steroid injection in your back is unlikely to help with pain caused by a slipped disc. But more research is needed before we can be certain.
What are they?
Doctors inject a kind of steroid into the spine to reduce swelling (inflammation). This helps with back pain and sciatica (pain that runs from one buttock and into one of your legs). Doctors call these epidural steroid injections.
Steroids are drugs that reduce swelling (inflammation).
You'll probably be given these injections by a specially trained doctor. This may be an anaesthetist or another type of medical specialist.
If you have pain in your lower back that's caused by a slipped disc, doctors inject these drugs into the area around your spinal cord. Doctors call this area the 'epidural space'.
These drugs are not the same type of steroids used by some athletes and bodybuilders. (Those are called anabolic steroids.) The drugs doctors use to treat back pain caused by a slipped disc are a direct copy of chemicals (corticosteroids) that our bodies produce naturally to deal with inflammation.
Steroids (and some brand names) used for a slipped disc include:
You may also have a local anaesthetic in the same injection.
The drugs are injected directly into the area around your spinal cord rather than into your bloodstream. This means there's less chance of the drugs affecting other parts of your body, so you should get fewer side effects.
To read more, see More about steroids injected into the spine.
How can they help?
We don't know if these injections can help. Different studies say different things.
Some studies suggest that steroid injections may help with back pain caused by a slipped disc, at least in the short term.    
But other studies have found the injections make no difference.   
In one study, standard surgery ( discectomy) worked better than steroid injections at first. But there was no difference between people who had one of these treatments after two to three years. 
How do they work?
If you have a slipped disc that's pressing on a nerve, you can get swelling around the nerve. That puts pressure on the nerve, which can cause pain.
Doctors think that these medicines may work because they affect chemicals in the body that cause inflammation. They keep those chemicals from causing inflammation, and that helps reduce pain.
Can they be harmful?
In one study, about 1 in 20 people had headaches or found that their sciatica got worse for a while soon after an injection of steroids into the spine. But these problems went away. 
Serious side effects are rare. A very small number of people get a kind of infection called an epidural abscess.