A knee injection is a commonly used non-surgical treatment for knee pain and knee osteoarthritis, designed to reduce inflammation, improve joint function, and delay progression of symptoms.
One of the most frequently asked questions by patients is:
how long do knee injections last?
The answer depends on the type of injection used, the severity of arthritis, and individual response to treatment.
At Alton Pain Clinic, we provide ultrasound guided knee injections, ensuring accurate placement and optimised treatment outcomes for patients with knee osteoarthritis.
How Long Do Knee Injections Last on Average?
How Long Do Different Knee Injections Last?
1. Cortisone (Steroid) Knee Injections
Cortisone injections for knee pain are used to reduce inflammation quickly.
How they work:
They suppress inflammation inside the knee joint, reducing swelling and pain.
Timeline:
- Onset of relief: 24–72 hours (sometimes up to 1 week)
- Duration: 2 weeks to 3 months
Best for:
- Sudden flare-ups of knee osteoarthritis
- Swelling and inflammatory knee pain
- Short-term pain control
Cortisone is effective but not long-lasting for all patients.
2. Hyaluronic Acid Knee Injections
Hyaluronic acid injections for knee osteoarthritis help improve lubrication within the joint.
How they work:
They act as a “joint lubricant and shock absorber,” improving movement and reducing friction.
Timeline:
- Onset of relief: 2–4 weeks
- Duration: 3 to 6 months
Best for:
- Mild to moderate knee osteoarthritis
- Stiffness and mechanical knee pain
- Improving joint mobility
3. PRP (Platelet-Rich Plasma) Knee Injections
PRP injections for knee osteoarthritis use concentrated growth factors from your own blood.
How they work:
They support natural healing and may improve joint environment over time.
Timeline:
- Onset of relief: 4–8 weeks
- Duration: 6 to 12 months (or longer in some patients)
Best for:
- Early to moderate knee osteoarthritis
- Patients seeking regenerative options
- Longer-term symptom improvement
4. Cingal Injection
Cingal combines hyaluronic acid + corticosteroid, offering both immediate and longer-term benefits.
Timeline:
- Onset of relief: within a few days
- Duration: several weeks to months
Best for:
- Patients needing fast relief + sustained improvement
- Moderate knee osteoarthritis pain
5. Arthrosamid Injection
Arthrosamid is a long-lasting injectable hydrogel designed to cushion the knee joint.
How it works:
It integrates into the joint lining and provides long-term shock absorption.
Timeline:
- Onset of relief: gradual over several weeks
- Duration: up to 12 months or longer in suitable patients
Best for:
- Persistent knee osteoarthritis symptoms
- Patients looking for longer-lasting non-surgical treatment
Why Do Knee Injection Results Vary?
The duration of a knee injection is not the same for everyone. It depends on:
- Severity of knee osteoarthritis
- Degree of cartilage loss
- Level of inflammation in the joint
- Type of injection used
- Activity levels after treatment
- Body’s individual response
Patients with advanced arthritis may experience shorter-lasting relief.
Do Knee Injections Cure Osteoarthritis?
No. Knee osteoarthritis injections do not cure the condition.
They are designed to:
- Reduce knee pain
- Improve mobility and function
- Reduce inflammation
- Delay progression of symptoms
- Potentially delay surgery
They are part of a symptom management strategy, not a permanent cure.
When Will You Feel the Effects?
The timeline varies depending on injection type:
- Cortisone: 1–3 days
- Hyaluronic acid: gradual over weeks
- PRP: slow, progressive improvement over 1–3 months
- Arthrosamid: gradual improvement over several weeks
Key Takeaway
A knee injection can last anywhere from a few weeks to over a year depending on the treatment used. Cortisone provides short-term relief, hyaluronic acid offers medium-term improvement, and treatments such as PRP and Arthrosamid may offer longer-lasting results in suitable patients.
At Alton Pain Clinic, we provide ultrasound guided knee injections tailored to each patient’s level of knee osteoarthritis, aiming to reduce pain, improve function, and support long-term joint health.
This article is intended for informational purposes only and should not replace professional medical advice. If you are experiencing persistent symptoms, please consult a qualified clinician.
Frequently Asked Questions
How long does a cortisone knee injection last?
Usually 2 weeks to 3 months, depending on severity of inflammation.
What is the longest-lasting knee injection?
PRP and Arthrosamid may provide relief for 6–12 months or longer in suitable patients.
Do knee injections work immediately?
Cortisone works quickly within a few days, while other injections take longer to show full effect.
Can knee injections be repeated?
Yes, knee injections for osteoarthritis can be repeated depending on clinical assessment and response.