Hyaluronic Acid Injections

What is hyaluronic acid?

Hyaluronic acid (brand names Synvisc, Osteoartz, Euflexxa) is used to treat osteoarthritis, a condition that affects the joints. It is most commonly used to treat osteoarthritis of the knee.

In a normal joint a layer of cartilage covers the ends of the bones. Cartilage helps the joint move smoothly and cushions the ends of the bones. In osteoarthritis cartilage breaks down and becomes thin. This leaves the ends of the bones unprotected and the joint loses its ability to move smoothly.

Hyaluronic acid is found naturally in joints and other parts of the body. In the joint it is found in the cartilage and the synovial fluid that lubricate the joints to keep them working smoothly. In people with osteoarthritis the hyaluronic acid gets thinner and it is no longer able to protect the joint.

Injections of artificial hyaluronic acid into affected joints may improve the protection. Hyaluronic acid injections are usually offered to people with osteoarthritis of the knee if other treatments have not worked or are unsuitable.

What benefit can you expect from your treatment?

Hyaluronic acid injections help reduce the pain caused by osteoarthritis. Some patients find relief from symptoms within a few days. Full benefits usually are reached 3-5 weeks after the treatment. The treatment may provide pain relief for up to 6 months. Response varies and the injections do not help everyone. If successful, the injections can be repeated after 6 months.

How is hyaluronic acid given?

Your doctor will inject the hyaluronic acid directly into the knee joint. Injections may be given once a week for three weeks or a single injection depending on the particular product your doctor recommends.

Are there any side effects?

Side effects from hyaluronic acid injections are not common. Most are limited to the site of injection and do not last long.

Most common possible side effects:

Local side affects may include:

  • redness and tenderness at the site of the injection
  • increased stiffness, swelling or warmth inflammation (flare) lasting 24 to 48 hours following the injection.

These local reactions may be treated by resting and applying ice to the injected area or by simple pain relievers.

Less common or rare possible side effects: These include: Allergy and Infection in the joint. Tell your doctor if you are concerned about possible side effects.

 What other precautions are necessary?

After the injection

  • It is recommended that strenuous activity (e.g. high impact sport such as jogging or tennis) or prolonged weight-bearing activities are avoided for about 48 hours after the injection.


  • Hyaluronic acid injections will not be given if you have an infection in your joint or a skin disease or infection around the area where the injection will be given.

Blood Thinners

  • You should tell your doctor about all medicines you are taking or plan to take especially blood thinning drugs such as warfarin. This includes over the counter, herbal or naturopathic medicines.


  • Hyaluronic acid injections will not be given if you have circulatory problems in your legs.
  • Tell your doctor if you have significant swelling or blood clots in your legs.