What to Expect After a Hyaluronic Acid Injection for Knee Arthritis
- Mar 1
- 5 min read
Written by Dr. Jeffrey Peng, MD — Board-Certified Sports Medicine Physician
Published: March 1, 2026 | Last Updated: March 1, 2026
If you've recently had a hyaluronic acid injection for knee arthritis—or you're considering one—you're probably wondering what comes next. Questions like "Is this soreness normal?" and "When will I start feeling better?" are among the most common things I hear from patients in my clinic. In this guide, I'll walk you through everything you need to know about the recovery process, including what's normal to feel, what's not, common mistakes to avoid, and how to set yourself up for the best possible outcome.
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What Is Hyaluronic Acid and Does It Work?
Hyaluronic acid is a gel-like substance that naturally exists in our joints. It functions as both a lubricant and a shock absorber, allowing the knee to glide smoothly during movement. As arthritis progresses and cartilage breaks down, the quantity and quality of this natural cushioning decreases—leading to increased stiffness and pain. The concept behind hyaluronic acid injections (also known as viscosupplementation) is straightforward: we are restoring some of that lost cushioning back into the joint.
The evidence supporting these injections is substantial. Multiple randomized controlled trials, systematic reviews, and meta-analyses have demonstrated that hyaluronic acid injections can meaningfully improve symptoms of knee osteoarthritis. A large-scale network meta-analysis comparing corticosteroids, hyaluronic acid, and platelet-rich plasma for knee osteoarthritis found that all injectable therapies provided significant pain relief and functional improvement compared to placebo, with no increase in treatment-related adverse events (Qiao et al., 2023).
Perhaps most compellingly, a landmark study from Korea involving nearly 37,000 patients found that those who received hyaluronic acid injections delayed knee replacement surgery by more than a year compared to those who did not (Park et al., 2024). Patients who received single-shot formulations showed the longest delay in time to surgery, and repeating injections over time provided even greater benefit. The hyaluronic acid group also demonstrated a significantly lower overall risk of requiring knee replacement (HR: 0.61), suggesting that these injections may play a meaningful role in postponing surgical intervention.
What to Expect in the First Few Days After Your Injection
It is completely normal to experience some mild soreness, stiffness, or even a bit of swelling in the knee for the first several days following your injection. This is your body's natural response to the procedure, and for the majority of patients, these symptoms resolve on their own within about a week.
A small number of patients may develop what is known as an acute flare—a more pronounced episode of pain and swelling that typically occurs within the first 6 to 24 hours after the injection. This is not an infection. Research suggests this reaction is related to mast cell activation, a component of your immune system. When mast cells become irritated, they release histamine, which causes localized swelling, warmth, and discomfort in the joint. This type of reaction, sometimes referred to in the medical literature as pseudoseptic arthritis, is rare and typically self-limiting (Aydın et al., 2017). It usually resolves with rest and an over-the-counter antihistamine such as cetirizine (Zyrtec), loratadine (Claritin), or diphenhydramine (Benadryl).
When Should You Be Concerned About Infection?
One of the most common concerns patients have after any joint injection is whether their symptoms could indicate an infection. The reassuring reality is that infections following hyaluronic acid injections are exceedingly rare. The large Korean database study of nearly 37,000 patients reported infection rates well below 1%, with many subgroups showing rates approaching zero (Park et al., 2024).
That said, it is important to recognize the warning signs. Unlike the temporary soreness or swelling that typically improves within a few days, an infection tends to worsen progressively over time. Red flags to watch for include escalating pain, significant swelling, spreading warmth or redness, fever, and a general feeling of being unwell. If you experience any of these symptoms—particularly if they emerge several days after the injection rather than immediately—contact your physician promptly.
What to Do After Your Hyaluronic Acid Injection
The most important guideline for the first 48 to 72 hours is to take it easy. Avoid strenuous physical activity, prolonged standing, and high-impact exercise during this initial window. Think of this period as an opportunity for your knee to settle and adjust to the injection.
Light walking around your home is perfectly fine, but hold off on long hikes, intense workouts, or extended time on your feet. Giving your knee this brief rest period helps you derive the maximum benefit from the injection in the weeks ahead.
During this time, applying ice for 10 to 15 minutes at a time and keeping your leg elevated can help manage any residual swelling or discomfort. I also recommend avoiding anti-inflammatory medications such as ibuprofen (Advil) or naproxen (Aleve) for at least 5 to 7 days following the injection. This may seem counterintuitive, but hyaluronic acid works in part by triggering a mild inflammatory response that promotes healing within the joint. Taking NSAIDs too early can blunt that beneficial effect. If you need relief from discomfort, acetaminophen (Tylenol) is generally the safer option during this period.
After the first few days, you can gradually return to your normal routine. Light walking, gentle stretching, and low-impact activities are appropriate, but reserve more demanding workouts, sports, or extended periods on your feet until at least one week has passed.
When Will You Start Feeling Relief?
Most patients begin to notice meaningful improvement in their symptoms approximately 10 to 15 days after the injection. The benefits then continue to build gradually over the following weeks. It is important to be patient during this period—hyaluronic acid works differently than a corticosteroid injection, which provides more immediate but shorter-lived relief. The onset with viscosupplementation may be slower, but the effects tend to be more sustained over time.
How to Maximize the Benefits of Your Injection
Once you are past the first week or two, the single most effective strategy to extend the benefits of your hyaluronic acid injection is to combine it with a structured exercise program. Research consistently demonstrates that strengthening the muscles around the knee—particularly the quadriceps, hamstrings, glutes, and calves—helps reduce pain, improve function, and prolong the duration of symptom relief.
A Cochrane systematic review analyzing 54 randomized controlled trials found that land-based therapeutic exercise significantly reduced knee pain and improved physical function in patients with knee osteoarthritis, with benefits persisting for at least 2 to 6 months after stopping the exercise program (Fransen et al., 2015). In my practice, I typically recommend that patients begin a simple home exercise program or work with a physical therapist starting about 1 to 2 weeks after the injection. This timing allows the joint to calm down while taking full advantage of the early improvements in pain and mobility that the injection provides.
If you're looking for a guided program to get started, I've put together a comprehensive knee arthritis rehabilitation protocol that I use with my own patients. You can find it on my knee arthritis exercises page.
References
1. Park JG, Sim J, Han SB. Association between intra-articular hyaluronic acid injections in delaying total knee arthroplasty and safety evaluation in primary knee osteoarthritis. BMC Musculoskelet Disord. 2024;25(1):706. doi:10.1186/s12891-024-07698-2
2. Qiao X, Yan L, Feng Y, et al. Efficacy and safety of corticosteroids, hyaluronic acid, and PRP and combination therapy for knee osteoarthritis: a systematic review and network meta-analysis. BMC Musculoskelet Disord. 2023;24(1):926. doi:10.1186/s12891-023-06925-6
3. Aydın M, Arıkan M, Toğral G, Varış O, Aydın G. Viscosupplementation of the knee: Three cases of acute Pseudoseptic Arthritis with painful and irritating complications and a literature review. Eur J Rheumatol. 2017;4(1):59-62. doi:10.5152/eurjrheum.2016.15075
4. Fransen M, McConnell S, Harmer AR, Van der Esch M, Simic M, Bennell KL. Exercise for osteoarthritis of the knee: a Cochrane systematic review. Br J Sports Med. 2015;49(24):1554-1557. doi:10.1136/bjsports-2015-095424
Disclaimer: This content is for educational purposes only and does not substitute for professional medical advice. Always consult with your physician or qualified healthcare provider before making decisions about your treatment. Individual results may vary.
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