Euflexxa is an injectable medication used to treatknee painin people withosteoarthritis(“wear-and-tear arthritis”). Euflexxa contains a synthetic version of hyaluronan, the key ingredient of synovial fluid found naturally in the joint space. This fluid thins and become less able to lubricate and protect the knee joint as the inflammatory stress of osteoarthritis takes its toll. By injecting Euflexxa into the area, the viscosity and shock-absorbing properties of the synovial fluid can be restored, reducing joint pain and stiffness.

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Euflexxa is commonly prescribed for people who have not found relief with more conservative forms of treatment, including exercise, physical therapy, or over-the-counter analgesics like Advil (ibuprofen) or Tylenol (acetaminophen). It is the first form of hyaluronan not derived from avian (bird) protein and is instead extracted from biologically modified bacteria.

Treatment GuidelinesThe American College of Rheumatology (ACR) 2019 guidelines for the treatment of knee osteoarthritis recommendagainstusing intra-articular hyaluronic acid injections for knee osteoarthritis.

Treatment Guidelines

The American College of Rheumatology (ACR) 2019 guidelines for the treatment of knee osteoarthritis recommendagainstusing intra-articular hyaluronic acid injections for knee osteoarthritis.

Treatment

Euflexxa is administered in a series of three weeklyintra-articular injections. Each dose is supplied in a pre-filled glass syringe. Prior to the injection, your healthcare provider may need to drain excess fluid from around the knee. This not only helps reduce the localized swelling, but it also prevents the dilution of hyaluronan when injected. The two-step process of drainage and joint lubrication is known asarthrocentesisplus viscosupplementation.

After drainage, the Euflexxa injection is delivered into the joint space in the mid-kneecap region. While the initial needle prick may cause discomfort, most people will tell you that the injection itself doesn’t cause any stinging or burning. It is only afterward that the body may react to the hyaluronan, triggering short-term inflammation and pain.

Your healthcare provider will likely advise you to avoid sports, strenuous exercise, running, or heavy lifting for the first 48 hours following the injection. Even standing for a long period of time should be avoided.

Effectiveness

Despite the potential benefits of treatment, viscosupplementation success rates can vary dramatically.

According to areportfrom the Arthritis Foundation, around 30 percent of users may experience complete pain relief for up to two years, while 20 percent will experience no relief at all. To date, scientists have been unable to explain this disparity.

What most healthcare providers will agree to is that viscosupplementation is not a quick fix. It is really only considered when conservative options have failed or as a means to delay more invasive procedures, such as knee surgery orknee replacement.

It is also often used in place of traditional corticosteroidknee injections. While corticosteroids can provide fast pain relief, usually within a few days, the benefits tend to last for only a month or so.However, the 2019 ACR treatment guideline for knee osteoarthritis prefers corticosteroid injections and recommends against hyaluronic acid injections.

Given the high variability of hyaluronan success rates, some healthcare providers will give their patients two shots—one with hyaluronan and the other with a corticosteroid—to provide fasting-acting, long-lasting relief.

Common Side Effects

The most common side effect of Euflexxa use is musculoskeletal pain. The symptoms tend to mild and short-lasting and rarely result in treatment termination. According to the pre-market clinical research, the following side effects were experienced in more than 1 percent of users:

The risk of allergy is considered low to negligible.

If you experience persistent or worsening pain, fever, swelling, redness, and body aches, call your healthcare provider immediately. These are signs of an infection that may require treatment.

Contraindications and Considerations

You need to avoid Euflexxa if you have a known hypersensitivity to hyaluronan, sodium hyaluronate, or hyaluronic acid. The shot should also be delayed if you have a knee infection or a skin infection in or around the injection site.

Unlike avian-derived hyaluronan, which can cause reactions in people with an egg or poultry allergy, Euflexxa is purified from specially bioengineered from bacteria and is not believed to be as immunogenic. (By contrast, avian-derived formulations such as Hyalgan, Orthovisc, Supartz, and Synvisc are made from chicken or rooster combs and should not be used if you have an egg or poultry allergy.)

While Euflexxa is not contraindicated in pregnancy, there is limited research into the effect of the drug on a developing fetus. It is also not known if Euflexxa is excreted in breast milk. Speak to your healthcare provider if you are pregnant or trying to get pregnant so that you can make an informed choice as to whether Euflexxa is right for you.

Cost and Insurance

While Euflexxa is may be less costly than other brands of viscosupplementation, it is still expensive, retailing at around $5,000 for the three-shot series. Therefore, it may be out of reach for even insured individuals who have a highcopay or coinsurancecosts.

Euflexxa is included in many drug formularies and will generally be approved if your healthcare provider can demonstrate that all other forms of conservative treatment have failed you.

A Word From Verywell

It is important to remember that Euflexxa is not a cure-all. It only provides short-term relief of knee stiffness and pain. It does not regrow lost cartilage or reverse the symptoms of osteoarthritis.

The 2019 American College of Rheumatology guidelines recommend against hyaluronic acid injections for knee osteoarthritis.

If you are unable to access Euflexxa, speak with your healthcare provider about alternative treatments such as intra-articular cortisone injections if your symptoms are especially severe.

If you are overweight, make an effort to lose weight with an appropriate diet andexercise planwhatever the stage of disease or treatment. Doing so may reduce the weight-bearing stress on your knee and help you better control your symptoms without the need for intra-articular medications.

8 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Altman RD, Manjoo A, Fierlinger A, Niazi F, Nicholls M.The mechanism of action for hyaluronic acid treatment in the osteoarthritic knee: a systematic review.BMC Musculoskelet Disord.2015;16:321. doi:10.1186/s12891-015-0775-zGoldberg VM, Goldberg L.Intra-articular hyaluronans: the treatment of knee pain in osteoarthritis.J Pain Res. 2010;3:51–56. doi:10.2147/jpr.s4733Kolasinski SL, Neogi T, Hochberg MC, et al.2019 American College of Rheumatology/Arthritis Foundation guideline for the management of osteoarthritis of the hand, hip, and knee.Arthritis Care Res (Hoboken). 2020;72(2):149-162. doi:10.1002/acr.24131. Erratum in: Arthritis Care Res (Hoboken). 2021 May;73(5):764.American Academy of Orthopaedic Surgeons.Viscosupplementation Treatment for Knee Arthritis.Bannuru RR, Natov NS, Obadan IE, Price LL, Schmid CH, Mcalindon TE.Therapeutic trajectory of hyaluronic acid versus corticosteroids in the treatment of knee osteoarthritis: a systematic review and meta-analysis.Arthritis Rheum.2009;61(12):1704-11. doi:10.1002/art.24925U.S. Food and Drug Administration.Product Information Euflexxa.de Rezende MU, de Campos GC.VISCOSUPPLEMENTATION.Rev Bras Ortop. 2015;47(2):160–164. doi:10.1016/S2255-4971(15)30080-XArthritis Foundation.Benefits of Weight Loss.

8 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Altman RD, Manjoo A, Fierlinger A, Niazi F, Nicholls M.The mechanism of action for hyaluronic acid treatment in the osteoarthritic knee: a systematic review.BMC Musculoskelet Disord.2015;16:321. doi:10.1186/s12891-015-0775-zGoldberg VM, Goldberg L.Intra-articular hyaluronans: the treatment of knee pain in osteoarthritis.J Pain Res. 2010;3:51–56. doi:10.2147/jpr.s4733Kolasinski SL, Neogi T, Hochberg MC, et al.2019 American College of Rheumatology/Arthritis Foundation guideline for the management of osteoarthritis of the hand, hip, and knee.Arthritis Care Res (Hoboken). 2020;72(2):149-162. doi:10.1002/acr.24131. Erratum in: Arthritis Care Res (Hoboken). 2021 May;73(5):764.American Academy of Orthopaedic Surgeons.Viscosupplementation Treatment for Knee Arthritis.Bannuru RR, Natov NS, Obadan IE, Price LL, Schmid CH, Mcalindon TE.Therapeutic trajectory of hyaluronic acid versus corticosteroids in the treatment of knee osteoarthritis: a systematic review and meta-analysis.Arthritis Rheum.2009;61(12):1704-11. doi:10.1002/art.24925U.S. Food and Drug Administration.Product Information Euflexxa.de Rezende MU, de Campos GC.VISCOSUPPLEMENTATION.Rev Bras Ortop. 2015;47(2):160–164. doi:10.1016/S2255-4971(15)30080-XArthritis Foundation.Benefits of Weight Loss.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Altman RD, Manjoo A, Fierlinger A, Niazi F, Nicholls M.The mechanism of action for hyaluronic acid treatment in the osteoarthritic knee: a systematic review.BMC Musculoskelet Disord.2015;16:321. doi:10.1186/s12891-015-0775-zGoldberg VM, Goldberg L.Intra-articular hyaluronans: the treatment of knee pain in osteoarthritis.J Pain Res. 2010;3:51–56. doi:10.2147/jpr.s4733Kolasinski SL, Neogi T, Hochberg MC, et al.2019 American College of Rheumatology/Arthritis Foundation guideline for the management of osteoarthritis of the hand, hip, and knee.Arthritis Care Res (Hoboken). 2020;72(2):149-162. doi:10.1002/acr.24131. Erratum in: Arthritis Care Res (Hoboken). 2021 May;73(5):764.American Academy of Orthopaedic Surgeons.Viscosupplementation Treatment for Knee Arthritis.Bannuru RR, Natov NS, Obadan IE, Price LL, Schmid CH, Mcalindon TE.Therapeutic trajectory of hyaluronic acid versus corticosteroids in the treatment of knee osteoarthritis: a systematic review and meta-analysis.Arthritis Rheum.2009;61(12):1704-11. doi:10.1002/art.24925U.S. Food and Drug Administration.Product Information Euflexxa.de Rezende MU, de Campos GC.VISCOSUPPLEMENTATION.Rev Bras Ortop. 2015;47(2):160–164. doi:10.1016/S2255-4971(15)30080-XArthritis Foundation.Benefits of Weight Loss.

Altman RD, Manjoo A, Fierlinger A, Niazi F, Nicholls M.The mechanism of action for hyaluronic acid treatment in the osteoarthritic knee: a systematic review.BMC Musculoskelet Disord.2015;16:321. doi:10.1186/s12891-015-0775-z

Goldberg VM, Goldberg L.Intra-articular hyaluronans: the treatment of knee pain in osteoarthritis.J Pain Res. 2010;3:51–56. doi:10.2147/jpr.s4733

Kolasinski SL, Neogi T, Hochberg MC, et al.2019 American College of Rheumatology/Arthritis Foundation guideline for the management of osteoarthritis of the hand, hip, and knee.Arthritis Care Res (Hoboken). 2020;72(2):149-162. doi:10.1002/acr.24131. Erratum in: Arthritis Care Res (Hoboken). 2021 May;73(5):764.

American Academy of Orthopaedic Surgeons.Viscosupplementation Treatment for Knee Arthritis.

Bannuru RR, Natov NS, Obadan IE, Price LL, Schmid CH, Mcalindon TE.Therapeutic trajectory of hyaluronic acid versus corticosteroids in the treatment of knee osteoarthritis: a systematic review and meta-analysis.Arthritis Rheum.2009;61(12):1704-11. doi:10.1002/art.24925

U.S. Food and Drug Administration.Product Information Euflexxa.

de Rezende MU, de Campos GC.VISCOSUPPLEMENTATION.Rev Bras Ortop. 2015;47(2):160–164. doi:10.1016/S2255-4971(15)30080-X

Arthritis Foundation.Benefits of Weight Loss.

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