Corticosteroid Injections for Knee Pain: Do They Work?
Key takeaways
- A corticosteroid injection puts a powerful anti-inflammatory steroid directly into the knee to calm inflammation and relieve pain for a period of weeks to months.
- The relief is real but temporary: most people get useful relief for a few weeks up to around 3 months, then it wears off.
- NICE recommends considering a steroid injection for short-term relief of a painful flare, alongside the core treatments of exercise and weight management.
- Injections are usually limited to no more than 3 or 4 per year in one joint, because frequent steroid can affect the joint over time.
- They can delay but not replace a knee replacement, which is considered when pain limits daily life and non-surgical measures no longer help.
By Margaret Doyle | Medically reviewed by Mr Paul Henderson, FRCS (Tr&Orth)
Updated June 15, 2026 · 4 min read
A corticosteroid injection puts a powerful anti-inflammatory steroid directly into the knee joint to calm inflammation and relieve pain, and the relief is real but temporary, usually lasting from a few weeks up to around 3 months. It is one of the most common treatments for a painful flare of knee arthritis, and it can help you stay active enough to do the exercise that matters most. This surgeon-reviewed guide explains how the injections work, how long they last, the risks, and where they fit on the road towards, or away from, surgery.
I had a steroid injection in my own knee before I came to surgery. It gave me a good few weeks where I could walk and sleep more comfortably, and then it faded; honestly, by then my joint was too worn for it to do much more. That is the realistic picture I want to give you here. If injections are no longer holding the pain back, it may be worth reading the signs you may need a knee replacement.
What is a corticosteroid injection for the knee?
A corticosteroid injection is an injection of a steroid medicine, often combined with a local anaesthetic, placed directly into the knee joint. The steroid is a strong anti-inflammatory, so it reduces the inflammation that drives the pain and swelling of arthritis. It is not the same as the anabolic steroids associated with bodybuilding; these are corticosteroids, the body’s own anti-inflammatory hormones in medicine form.
The injection is a quick outpatient procedure done in sterile conditions, sometimes guided by ultrasound to place it accurately. It treats the symptoms rather than the underlying cause, so it sits alongside the core treatments of exercise, weight management, and pain relief rather than replacing them1.
Do corticosteroid injections for the knee work?
Yes, for many people, but the benefit is short-term. A steroid injection reliably calms inflammation and can give meaningful pain relief, which is most useful for getting through a flare or staying active enough to keep up your physiotherapy. NICE recommends considering an intra-articular corticosteroid injection for the short-term relief of osteoarthritis symptoms, alongside the core treatments of exercise and weight management2.
The honest framing is that it is a window of relief, not a cure. It works best when the joint is not too badly worn; in advanced arthritis the relief tends to be shorter each time.
How long does the relief last?
Most people get useful relief for a few weeks up to around 3 months, after which it gradually wears off1. The exact duration varies a great deal from person to person and depends largely on how much wear is in the joint. Some people get several good months; others, with a badly worn knee, find it fades within weeks. The first day or two can actually be a little sorer (a “steroid flare”) before the benefit kicks in.
How often can you have them, and what are the risks?
Injections into one joint are usually limited to no more than 3 or 4 per year, with several months between them, because frequent steroid into the same joint can affect the cartilage over time1. Most people have no serious problems, but the risks to be aware of are:
- A short-lived flare of pain in the first day or two.
- A small risk of infection, which is why it is done in sterile conditions.
- Thinning or colour change of the skin at the injection site.
- A temporary rise in blood sugar in people with diabetes.
- A possible effect on the joint cartilage with frequent, repeated injections.
If you are needing injections often, that is usually a sign the underlying joint damage warrants a wider conversation about your options.
How do injections fit with a knee replacement?
Injections can delay a knee replacement but do not replace it. For moderate arthritis they can control flares and keep you active for months or years; for a badly worn joint the relief gets shorter each time, which is often the point at which surgery is discussed. A knee replacement is considered when pain limits everyday life and non-surgical measures no longer help enough, and around 90 to 95% of knee replacements are still in place at 10 years3.
There is one important practical point on timing: surgeons usually prefer a gap of around 3 months between a steroid injection and a knee replacement in that joint, because an injection close to surgery may raise the infection risk4. Always tell your surgical team about any recent injections. The full set of non-surgical options is in the alternatives to knee replacement, and the operation itself is in our complete guide to knee replacement surgery.
References
- Steroid injections, Versus Arthritis. ↩
- Osteoarthritis in over 16s: diagnosis and management (NG226), NICE. ↩
- Osteoarthritis of the Knee (OrthoInfo), American Academy of Orthopaedic Surgeons. ↩
- Knee pain, NHS. ↩
Common questions
How long does a corticosteroid injection in the knee last?
The relief is temporary. Most people get useful relief for a few weeks up to around 3 months, then it gradually wears off. How long it lasts varies a lot from person to person and depends on how much wear is in the joint. It works best for calming a painful flare rather than as a permanent fix.
How often can you have steroid injections in the knee?
Injections into one joint are usually limited to no more than 3 or 4 per year, with a gap of several months between them. This is because frequent steroid into the same joint can, over time, have a negative effect on the cartilage. If you are needing them often, that is usually a sign the underlying joint damage warrants a wider conversation.
Do steroid injections in the knee actually work?
Yes, for many people, but the benefit is short-term. A corticosteroid injection reliably calms inflammation and can give weeks to a few months of meaningful pain relief, which is useful for getting through a flare or staying active enough to do physiotherapy. NICE recommends considering one for short-term relief alongside exercise and weight management.
What are the risks of a steroid injection in the knee?
Most people have no serious problems. The main risks are a short-lived flare of pain in the first day or two, a small chance of infection (which is why it is done in sterile conditions), thinning or colour change of the skin at the site, a temporary rise in blood sugar in people with diabetes, and, with frequent injections, a possible effect on the joint cartilage over time.
Will a steroid injection delay a knee replacement?
It can buy time, but it does not replace surgery. For someone with moderate arthritis, injections can help control flares and stay active for months or years. For a badly worn joint, the relief tends to be shorter each time. A knee replacement is considered when pain limits daily life and non-surgical measures no longer help enough.
Can you have a steroid injection close to knee replacement surgery?
Surgeons usually prefer a gap between a steroid injection and a knee replacement, because an injection close to surgery may raise the infection risk. A common precaution is to avoid operating for around 3 months after an injection into that knee. Always tell your surgical team about any recent injections so they can plan the timing safely.
Written by Margaret Doyle. Medically reviewed by Mr Paul Henderson, FRCS (Tr&Orth).
Our guides are written from personal experience and reviewed by a qualified clinician for accuracy. Read our editorial policy.