Commonly Discussed Injections
What is a cortisone injection, and how does it work?
A cortisone (corticosteroid) injection delivers a strong anti-inflammatory medication directly into the joint. It works by calming the inflammation that causes pain and swelling, usually providing relatively fast relief that typically peaks within 4 to 6 weeks.³,⁴
What is a hyaluronic acid injection, and how does it work?
Hyaluronic acid is a gel-like substance that occurs naturally in healthy joint fluid. Injecting it into an arthritic joint helps cushion and lubricate the joint, reducing friction and pain. It also has mild anti-inflammatory effects, with peak relief typically reached around 6 to 8 weeks.²,⁵
What is a PRP injection, and how does it work?
Platelet-rich plasma (PRP) is made from a small sample of your own blood, which is spun down to concentrate the platelets and their healing growth factors. When injected into the joint, these growth factors may help reduce inflammation and support tissue repair. Relief tends to build gradually, often peaking around 3 months.²,³
The Injection Options
Which injection is most effective for joint arthritis?
At 6 months and beyond, PRP tends to provide the greatest improvement in both pain and function for a single injection, followed by hyaluronic acid. Corticosteroids may offer rapid short-term relief, but their benefit typically fades within a few weeks to months. However, they can be injected multiple times throughout the year to control symptoms.¹,⁶
How do cortisone, hyaluronic acid, and PRP injections compare?
Corticosteroids usually work the fastest but tend to wear off the soonest. Hyaluronic acid generally provides moderate, longer-lasting relief, while PRP tends to offer the most sustained benefit, with pain and function improvements lasting up to a year in many patients.¹,³ Your surgeon will recommend the best option based on the severity of your arthritis, your overall health, and your personal preferences.
Can hyaluronic acid and PRP be combined?
Often, yes; combining PRP with hyaluronic acid may offer better long-term pain relief than either injection alone, and the combination appears to be safe generally.⁷,⁸ Your surgeon can advise whether a combined approach is appropriate for your situation.
Who Is A Candidate
Is a joint injection worth it, and who is a good candidate?
Injections tend to work best for people with mild to moderate arthritis who still have reasonably preserved joint space on X-ray. They may be a good option when oral medications, exercise, and physiotherapy have not provided enough relief, or when you need to manage pain for an important event or activity.⁵,⁹
Who should not have a cortisone injection?
Corticosteroid injections should generally not be given if there is an active infection in or near the joint, a fracture, or a serious allergy to the medication. They require extra caution in people with diabetes, as they can raise blood sugar for up to two weeks, and in anyone considering joint replacement surgery within the next three months.⁵
Can injections help you delay or avoid joint replacement?
For mild to moderate arthritis, injections can meaningfully reduce pain and may help postpone surgery. Once arthritis is advanced and other treatments have been tried for at least 6 months, however, it is recommended not to delay joint replacement solely for further injections.¹⁰,¹¹
What to Expect After Treatment
Can you walk or drive after a joint injection?
Most people can usually walk right away, and driving ability is generally not affected. It is advisable to take it easy for the first 1-2 days and to avoid strenuous activity for several days.¹²,¹³
What should you avoid after a cortisone injection?
Avoid heavy exercise and high-impact activities for at least a few days. Some physicians recommend limiting weight-bearing for 1 to 2 days to help the medication work optimally. Watch for worsening pain, swelling, or fever beyond 2 to 3 hours, as these could signal a joint infection, a rare complication that may need prompt attention.¹³,¹⁴
How long does an injection take to start working?
Corticosteroid injections may begin easing pain within a few days, with peak effect at approximately 4 to 6 weeks. Hyaluronic acid typically peaks around 6 to 8 weeks. PRP builds more gradually, often reaching full effect by about 3 months.³,⁵
The Risks
What are the most common side effects of cortisone injections?
Although usually mild, the most common side effects are temporary soreness or swelling at the injection site, occurring in approximately 3 to 25% of patients.⁵ Less common risks include a short-term blood sugar rise in people with diabetes and, with long-term repeated use, possible thinning of the joint cartilage. Serious complications such as joint infection are rare.¹⁵,¹⁶
Why are doctors sometimes cautious about cortisone injections?
Repeated corticosteroid injections given on a fixed schedule (such as every 3 months) have been linked to some cartilage loss over time.¹⁵ When used only as needed for symptom flare-ups however, this risk appears to be much lower.
What are the downsides of hyaluronic acid and PRP injections?
Both injections are generally well tolerated. Hyaluronic acid injections may cause temporary swelling or pain in approximately 2 to 6% of patients. PRP may cause mild soreness and swelling in approximately 1 in 10 patients, which usually resolves on its own within a few days.⁵,¹⁷ Serious side effects are very rare for both.¹⁸
Your surgeon will discuss these risks with you before treatment, including any others specific to your health, and how they apply to your individual case.
The Years Ahead
How long does each type of injection last?
Corticosteroid relief commonly lasts a few weeks, with benefit fading by about 3 months.⁴,¹⁹ Hyaluronic acid typically provides relief for approximately 6 months.⁵,²⁰ PRP may provide continued benefit for up to a year.³
How often can injections be repeated?
Corticosteroid injections should generally not be repeated more often than every 3 months.⁵ Hyaluronic acid can typically be repeated every 6 months. There is no firm consensus on PRP frequency, but courses are often repeated annually if needed; your surgeon can guide the timing based on your response.²⁰
What are the next steps if an injection doesn’t work?
If injections and other conservative measures (exercise, weight management, physiotherapy, oral medications) have not provided adequate relief after at least 6 months, a surgical consultation for joint replacement may be the next step. More than 8 out of 10 joint replacement recipients then report substantial improvement in pain.⁹,¹¹
