Euflexxa is not a steroid. It is a viscosupplement, a completely different class of injectable treatment. The active ingredient is sodium hyaluronate, a purified form of hyaluronic acid, which is a substance your body naturally produces in joint fluid. While both Euflexxa and steroid injections are delivered into the knee joint to treat osteoarthritis pain, they work in fundamentally different ways.
What Euflexxa Actually Is
Euflexxa is a gel-like solution made of highly purified hyaluronic acid suspended in a saline buffer. Each injection contains 20 mg of sodium hyaluronate produced through bacterial fermentation, not derived from animal tissue. The FDA approved it in 2004 specifically for knee osteoarthritis pain in people who haven’t gotten enough relief from basic treatments like over-the-counter pain relievers or physical therapy. Importantly, the FDA classifies it as a medical device rather than a drug.
Corticosteroids, by contrast, are synthetic versions of hormones your adrenal glands produce. They suppress inflammation broadly throughout the tissue they reach. Euflexxa contains no corticosteroid compounds whatsoever.
How It Works in the Knee
In a healthy knee, the synovial fluid that fills the joint space is thick and slippery, largely thanks to hyaluronic acid. This fluid acts as both a lubricant and a shock absorber. In osteoarthritis, the concentration and quality of hyaluronic acid in that fluid breaks down, leaving the joint less cushioned and more prone to pain with movement.
Viscosupplementation aims to restore some of that lost cushioning by injecting hyaluronic acid directly into the joint space. Beyond the mechanical lubrication, hyaluronic acid also appears to reduce levels of inflammatory molecules and enzymes that break down cartilage. So while Euflexxa isn’t an anti-inflammatory drug in the traditional sense, it does have some indirect anti-inflammatory effects. The key distinction is that it supplements a natural joint component rather than suppressing the immune system the way steroids do.
Euflexxa vs. Steroid Injections
The practical difference that matters most is timing. Steroid injections tend to work faster, often providing noticeable relief within days. Euflexxa takes longer to kick in since the full treatment requires three weekly injections before you can expect the full benefit. In clinical comparisons, both treatments produced similar pain reduction at one and two months.
Where they diverge is durability. In a randomized controlled trial comparing the two, steroid injections lost their effectiveness before three months, with pain scores returning to pre-injection levels. Hyaluronic acid injections, on the other hand, maintained significantly lower pain scores past the three-month mark. Researchers concluded that the most important difference between the two is how long the relief lasts, with hyaluronic acid showing a clear advantage in duration.
Steroid injections also carry concerns with repeated use. Frequent corticosteroid injections may accelerate cartilage breakdown over time, which is why most providers limit them to three or four per year in a single joint. Euflexxa doesn’t carry the same risk to cartilage, making it an option for people who need ongoing management without the cumulative downsides of steroids.
What the Treatment Looks Like
A full course of Euflexxa involves three injections, each given one week apart. Your provider injects the solution directly into the knee joint, typically after removing any excess fluid that may have built up. The procedure itself takes only a few minutes. Most people experience little more than mild discomfort at the injection site. In the large FLEXX clinical trial, injection-site reactions occurred in roughly 1% of patients, a rate identical to the placebo group.
After each injection, you may be advised to avoid strenuous activity for about 48 hours. Pain relief generally builds over the course of the treatment series and in the weeks following the final injection. If the treatment works well, the effects can last several months before a repeat course is needed.
How Well It Works
The evidence on viscosupplementation is genuinely mixed, and it’s worth knowing that going in. Some patients report meaningful pain relief that lasts for months. Others notice little difference. The American Academy of Orthopaedic Surgeons notes that the most recent research has not found viscosupplementation to be significantly effective at reducing pain or improving function across all patients, though it has been proposed that the treatment works best in earlier stages of arthritis, when the joint hasn’t yet deteriorated severely.
That said, individual responses vary widely. People with mild to moderate osteoarthritis tend to be better candidates than those with advanced joint damage. If the cartilage in your knee is largely gone, adding lubrication to a bone-on-bone joint is unlikely to make a meaningful difference.
Why the Confusion With Steroids
The mix-up is understandable. Both Euflexxa and corticosteroid injections are administered the same way (a needle into the knee joint), treat the same condition (osteoarthritis pain), and are often discussed together in the same appointment. Many insurance plans also group them into a treatment sequence, sometimes requiring that you try one before covering the other. But the similarity ends at the delivery method. Chemically, biologically, and in terms of side effects, they are entirely different treatments.
If you’ve been told you can’t have more steroid injections due to frequency limits or side effects, Euflexxa represents a genuinely different option rather than just another version of the same thing. Conversely, if you need fast-acting relief for a flare-up, a steroid injection will likely work more quickly, even if the benefit fades sooner.