How a Cortisone Shot Works
Cortisone shots, or corticosteroid injections, are a synthetic version of cortisol, a hormone naturally produced by the adrenal glands to combat inflammation. When injected directly into a painful knee joint, the powerful anti-inflammatory medication works locally to suppress the immune system's inflammatory response, which in turn reduces swelling, stiffness, and pain. The procedure is relatively quick, typically performed in a doctor's office, and often includes a local anesthetic like lidocaine to numb the area, providing immediate, albeit brief, relief.
The Immediate Help: A Temporary Bridge to Relief
For many patients, cortisone shots can offer a period of significant, rapid pain relief, often starting within a few days of the injection. This can be particularly helpful for managing flare-ups of conditions such as:
- Osteoarthritis, the most common form of arthritis resulting from cartilage breakdown.
- Tendonitis, inflammation of the tendons around the knee.
- Bursitis, inflammation of the fluid-filled sacs (bursae) that cushion the joint.
The pain relief, which may last anywhere from several weeks to several months, can allow a patient to more effectively participate in physical therapy, which is crucial for long-term recovery. It can also provide a temporary reprieve for individuals with end-stage arthritis while they await knee replacement surgery. The effectiveness, however, varies from person to person and is not a permanent fix, as it does not address the root cause of the joint damage.
The Risks: Long-Term Concerns and Side Effects
While cortisone's ability to reduce inflammation is well-documented, a growing body of recent research indicates potential long-term harm to the knee joint, particularly with repeated use. Studies presented at the Radiological Society of North America (RSNA) in 2022 and published in Radiology in 2025 raised serious concerns:
- Cartilage Degeneration: Patients with knee osteoarthritis receiving corticosteroid injections showed significantly greater progression of arthritis, including faster cartilage loss, compared to those who received no treatment or hyaluronic acid injections.
- Bone Health: Repeated injections have been linked to subchondral bone changes and, in some cases, the death of nearby bone tissue.
- Risk of Infection: As with any injection, there is a rare but serious risk of joint infection, which can be particularly damaging.
For these reasons, doctors typically limit cortisone shots in a single joint to a few per year.
Comparison of Knee Injection Options
For managing knee pain, cortisone is not the only option. Alternative injections offer different benefits and drawbacks, and should be discussed with a healthcare provider.
| Feature | Cortisone (Corticosteroid) | Hyaluronic Acid (HA) | Platelet-Rich Plasma (PRP) |
|---|---|---|---|
| Mechanism | Powerful anti-inflammatory effect. | Restores lubrication and acts as a shock absorber. | Concentrated growth factors from patient's blood to stimulate healing. |
| Effect Duration | Short-term relief, weeks to a few months. | Longer-lasting relief, often 4-5 months or more. | Can provide longer-lasting relief than cortisone, possibly promoting tissue healing. |
| Long-Term Joint Impact | Potential for accelerated cartilage damage and degeneration. | No known harmful effects on cartilage; may help slow progression. | Research is ongoing, but may support cartilage health and tissue regeneration. |
| Frequency | Limited to 3-4 times per year in the same joint. | One to five injections in a course, repeatable. | Varies, depends on the condition being treated. |
| Best For | Acute, severe inflammatory flare-ups, or short-term relief before other treatments or surgery. | Patients with mild to moderate osteoarthritis, especially if they have diabetes. | Mild to moderate osteoarthritis and tendon/ligament injuries. |
Integrating Physical Therapy for Optimal Results
Regardless of the injection chosen, physical therapy is often a crucial component of a long-term treatment plan. The temporary pain relief from a cortisone shot can provide a window of opportunity to perform targeted exercises that strengthen the muscles supporting the knee joint. Building strength and improving joint stability through physical therapy can lead to more durable pain relief and better function, addressing some of the underlying issues that caused the pain in the first place. A physical therapist can guide a patient through a safe and effective exercise regimen.
Navigating the Decision: What's Right for You?
Deciding on the best course of action for knee pain is a personalized process that requires a detailed discussion with your healthcare provider. Factors to consider include the severity of your condition, your overall health, and your treatment goals. While a cortisone shot can be a powerful tool for short-term pain relief, especially during an acute flare-up, it is critical to weigh this benefit against the risks of long-term joint degradation. Modern guidelines and emerging research point toward a more cautious approach, emphasizing cortisone as part of a broader strategy that often incorporates physical therapy and may consider alternatives like hyaluronic acid or PRP, particularly for patients with mild to moderate osteoarthritis. A comprehensive knee care path should focus on both symptom management and protecting the joint's long-term health.
Conclusion
So, do cortisone shots in the knee really help? The answer is nuanced. They can provide significant, rapid, and effective short-term pain relief by powerfully reducing inflammation. However, they are not a cure and recent research suggests they may accelerate cartilage damage over the long term, making them a less ideal choice for routine, frequent use. For conditions like osteoarthritis, focusing on a multimodal treatment plan—including physical therapy and considering alternative injections like hyaluronic acid—may offer a better strategy for both managing symptoms and preserving joint health over time. Discussing all options with a qualified healthcare provider is the essential first step toward a more active and comfortable future.
Frequently Asked Questions
How long does pain relief from a cortisone shot in the knee typically last?
Relief varies widely but generally lasts anywhere from several weeks to a few months. The duration can be shorter for more severe cases of arthritis.
Are there any restrictions after getting a cortisone shot in the knee?
Yes, doctors typically advise patients to rest and protect the joint for 24-48 hours after the injection, avoiding heavy lifting or strenuous activity. Gentle movement can often be resumed after this period.
Is it painful to get a cortisone shot in the knee?
Discomfort from the injection is usually brief, as a local anesthetic is often used. Some patients may experience a temporary increase in pain and swelling for 1-2 days after the shot, known as a 'cortisone flare'.
How often can you receive cortisone shots in the knee?
Due to the risk of joint damage, most doctors recommend limiting injections to no more than 3-4 times per year in the same joint.
Can cortisone shots cure arthritis in the knee?
No, cortisone shots do not cure arthritis. They only treat the symptoms by reducing inflammation. They do not repair or regrow damaged cartilage.
What are the main side effects of a cortisone shot in the knee?
Common side effects include a temporary flare of pain, swelling at the injection site, and facial flushing. More serious risks include infection, thinning of skin and cartilage damage, especially with repeated injections.
What are some alternatives to cortisone shots for knee pain?
Alternatives include hyaluronic acid injections, PRP injections, physical therapy, weight management, anti-inflammatory medications, and lifestyle modifications.
Can cortisone shots affect blood sugar levels?
Yes, for individuals with diabetes, a cortisone shot can temporarily increase blood sugar levels for a few days. Diabetic patients should monitor their levels closely after an injection.
