Are Cortisone Injections Safe for Your Knees? What You Really Need to Know

Knee pain is one of the most common reasons people visit their doctor, and cortisone injections remain one of the most frequently prescribed treatments. I frequently get this question on how effective the injections are. But here’s the real question: Are they actually safe—and do they really help? Whether you’re dealing with arthritis, a meniscus tear, overuse pain, or chronic inflammation, understanding how cortisone works (and its limits) can help you make a smarter, more confident decision about your knee health.

What Cortisone Actually Does Inside the Joint

Cortisone is a powerful anti-inflammatory—not a painkiller. When injected into the knee, it works by reducing inflammation inside the joint, which in turn lowers pain and swelling.

It does not rebuild cartilage. It does not fix structural damage. Its job is simple: turn down inflammation so you feel better.

Most people start feeling relief within 24–72 hours, though some experience a brief “post-injection flare” where the knee feels more irritated for 24 hours before improving.

How Long Does the Pain Relief Last?

For most people:

• Mild arthritis: 6–12 weeks of relief

• Moderate arthritis: 4–6 weeks

• Severe arthritis: Relief may be very short-lived

Cortisone is most effective when inflammation is the main issue—not when the joint is structurally worn down.

Risks & Side Effects You Should Know

Cortisone is safe when used appropriately, but it’s not risk-free.

Possible concerns include:

• Cartilage damage when injections are done too frequently

• Temporary elevation in blood sugar (important for diabetics)

• Post-injection flare

• Skin thinning or discoloration at the injection site

Because of these risks, most orthopedic guidelines suggest no more than 3–4 cortisone injections per year in the same joint.

When Cortisone Helps

Cortisone is most effective for:

• Arthritis with significant inflammation

• Synovitis (joint lining inflammation)

• Bursitis

• Pain interfering with sleep or mobility

• Flare-ups that prevent therapy or exercise

Think of cortisone as a reset button—it calms inflammation so you can move, strengthen, and heal.

When Cortisone Might NOT Be the Best Option

You may need to consider alternatives if:

• You’ve already had multiple injections with little relief

• You have advanced bone-on-bone arthritis

• Your goal is cartilage repair (cortisone does not help)

• Your pain is coming from instability or mechanical issues

• You’re hoping for a long-term fix instead of short-term relief

Other injection options include hyaluronic acid, PRP, and biologics—each with different purposes and success rates.

Bottom Line

Cortisone injections can be safe, effective, and incredibly helpful—when used at the right time, for the right patient, and in the right frequency. They reduce inflammation, improve function, and make movement possible again. But they are not a cure and not a long-term strategy on their own.

If you want clear, actionable, science-based guidance on aging stronger—not slower—subscribe to the 10-Minute Longevity Newsletter.

Your knees (and future self) will thank you.