Synvisc and Synvisc-One Use and Side Effects

Synvisc (hylan G-F 20) is an elastic, viscous, high molecular weight fluid which contains hylan A fluid, hylan B gel, and salt water. Hylan A and hylan B are derived from hyaluronan (also called sodium hyaluronate) which is made from chicken combs. Hyaluronan is also a natural substance found in the body, specifically, in large amounts in the joints. The body's natural hyaluronan acts as a lubricant and shock absorber which is necessary for normal joint function.

Synvisc is one of the hyaluronates that is used in a treatment known as viscosupplementation. The treatment is sometimes referred to as joint fluid therapy, hyaluronan injections, or hyaluronate injections.

Man holding syringe
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Synvisc injections are approved for the treatment of pain in patients with osteoarthritis of the knee who have failed to respond to more conservative therapy, such as non-narcotic analgesics or non-drug treatment options. In osteoarthritis, there may be insufficient amounts of hyaluronan or the quality of hyaluronan may be diminished. The use of Synvisc for other joints is being investigated, but it is not yet approved.

Synvisc is injected three times, once a week, using a syringe containing 2.25 ml, directly into the knee joint to restore the cushioning and lubricating properties of normal joint fluid. There is another Synvisc product, known as Synvisc-One, that is administered as a single (one-time) intra-articular injection (6 ml).


  • Viscosupplementation has been studied for osteoarthritis treatment since the 1970s.
  • Synvisc was FDA approved on 08/08/97.
  • Synvisc injections are typically given as a series of 3 injections, once a week, one full week apart. Synvisc-One was developed as a one-time injection, as an alternative to the series of three with Synvisc.
  • To get the best results, osteoarthritic synovial fluid is typically removed from the knee before the first injection.
  • Synvisc is considered a treatment or therapy, not a drug.

Side Effects and Risks

The most common side effects associated with Synvisc injections include pain in the injected knee, swelling in the injected knee, and joint effusion. Other potential adverse events that may occur with intra-articular injections include arthralgia (pain in a joint), joint stiffness, joint effusion, joint swelling, joint warmth, pain at the injection site, arthritis, arthropathy, and gait abnormality.

Post-marketing surveillance of the 3-injection regimen of Synvisc revealed other rare systemic effects including rash, hives, fever, nausea, headache, dizziness, chills, muscle cramps, malaise, respiratory issues, peripheral edema, and rarely, thrombocytopenia (low platelets).

Contraindications and Warnings

Synvisc should not be injected into patients with known hypersensitivity to hyaluronan products. Also, Synvisc should not be injected into knees with joint infection, skin diseases or infections, or infection in the area that surrounds the injection site.

It should also not be used (or used with caution) in people with allergies to avian proteins, feathers, or egg products; those with lymphedema or venous stasis; or those with inflammation within the knee joint (such as in RA or psoriatic arthritis)

Synvisc should only be used as an intra-articular injection (within the joint). If it is injected outside the joint in the synovial tissue or joint capsule, local or systemic adverse events can occur. Intravascular injection of Synvisc (into a blood vessel) can cause systemic adverse events and should be avoided.

After a Synvisc injection, it is recommended that patients should avoid strenuous activities or prolonged weight-bearing activities for 48 hours. Discuss specific recommendations pertaining to your individual case with your healthcare provider.

According to the American Academy of Orthopaedic Surgeons, the most recent research has not found viscosupplementation to be effective at significantly reducing pain or improving function, although some patients do report pain relief with the procedure. It is not recommended by the American College of Rheumatology either.

The safety and effectiveness of Synvisc in pregnant women or women who are nursing has not been established.

If you have allergies to feathers, eggs, poultry, or other products from birds, notify your healthcare provider.

Comparing Synvisc to Corticosteroid Injections

Synvisc is comparable in effectiveness to intra-articular corticosteroid injections which have a quicker onset but shorter duration of action than Synvisc. Repeated injections of Synvisc is considered safer than corticosteroids in patients with comorbidities which may make corticosteroids contraindicated. Also, it should be noted that NSAID use may decrease in some patients following Synvisc injections.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Prescribing Information Synvisc-One. Sanofi US. Revised Sep 2014

  2. Patient Information Synvisc, Sanofi US. Revised September, 2014

  3. Magliore A. et al. Hylan G-F 20: Review of its Safety and Efficacy in the Management of Joint Pain in Osteoarthritis. Clinical Medical Insights: Arthritis Musculoskeletal Disorders. 2010; 3: 55–68. PMID: PMC2998981

Additional Reading

By Carol Eustice
Carol Eustice is a writer covering arthritis and chronic illness, who herself has been diagnosed with both rheumatoid arthritis and osteoarthritis.