Hyaluronic acid (HA) is a naturally occurring substance in the body that helps lubricate and cushion the joints and keep the cells hydrated. In some cases, HA injections may help reduce the symptoms of osteoarthritis.

This treatment is most likely to be effective for individuals with mild to moderate osteoarthritis and may not work well for people with more severe symptoms.

It is also possible to purchase HA supplements, which some evidence suggests may be helpful for osteoarthritis. However, there is less evidence to support this approach, and it is not a treatment that the Food and Drug Administration (FDA) has approved.

This article looks at HA for osteoarthritis, including how it works, how effective it is, who is eligible, and the possible side effects.

Close-up of water splashing on someone's legs to represent hyaluronic acid.Share on Pinterest
Jena Ardell/Getty Images

HA is a substance that exists in the human body. It is a humectant, which means that it traps moisture inside cells, keeping them hydrated. HA is part of the skin, eyes, and joints. Inside joints, HA is a key component of synovial fluid, which is responsible for cushioning and lubricating the bones as they move.

When a person has osteoarthritis, the joints are less able to glide smoothly due to cartilage degradation. The quality of the HA in the synovial fluid decreases, and inflammatory molecules become mixed into it. This can result in pain or swelling.

HA injections work by delivering HA directly to the joint, helping reduce friction and inflammation. In this way, they can decrease the symptoms of osteoarthritis for some people.

At present, the FDA has only approved HA injections for use in the knees, but doctors may prescribe this treatment off-label for other large joints, such as the hips or shoulders.

Research suggests that HA is an effective tool for managing osteoarthritis. A 2015 study looked at a group of 40 individuals who received five weekly injections of HA. At 6 months, 60% showed no worsening of cartilage damage, and 32.5% showed an improvement.

A person may require multiple HA injections before they notice an improvement in their symptoms. However, symptom relief from this treatment can last up to 6 months or possibly even 1 year in some cases.

HA is not a cure for osteoarthritis, though. It neither helps cartilage grow back nor improves the structure of the joints. Instead, it reduces inflammation. Therefore, the symptoms will eventually come back.

A person will need to get HA injections periodically to maintain the effects.

HA injections do not work for everyone. Typically, the injections are most effective in individuals with mild to moderate osteoarthritis. Doctors cannot predict how useful HA will be for people with more advanced arthritis.

People who may particularly benefit from HA injections include individuals who do not respond well to nonsteroidal anti-inflammatory drugs (NSAIDs) and those with diabetes who wish to avoid taking corticosteroids. Corticosteroids are a class of drugs that can reduce inflammation, but they can also increase blood sugar levels.

Currently, experts do not know how HA injections could affect pregnancy or breast milk, so a doctor may suggest an alternative to HA for people who are pregnant or nursing.

HA injections for osteoarthritis typically involve the following steps:

  1. A healthcare professional will clean the skin around the injection site. They may also apply a topical anesthetic to numb the area.
  2. Next, a doctor will decide whether to withdraw fluid from the joint. They may do this if the joint is swollen due to excess synovial fluid.
  3. The doctor will then inject HA into the space between the bones using a sterile needle.
  4. After the injection, the doctor will dress the area with a bandage.

After an HA injection, a person may experience mild pain, swelling, or stiffness around the joint. Resting after the HA injection may help reduce pain and decrease the possibility of the body flushing HA away from the joint. Applying an ice pack may also help.

A person will need to avoid strenuous weight-bearing exercise for a couple of days, but they can otherwise resume their usual activities.

People usually receive HA injections once weekly for 3–5 weeks, depending on the brand.

HA injections are a low risk treatment. They often have fewer side effects than other osteoarthritis treatments, and people tend to tolerate them well. As HA is a substance that the body naturally produces, HA injections rarely cause an allergic reaction.

However, people can experience some mild side effects after the injection, which typically resolve within 1 week. These may include:

  • pain
  • skin discoloration at the site of the injection
  • itching
  • swelling
  • bruising

These symptoms probably occur because of the injection causing an injury rather than because of the HA itself.

Very rarely, people can develop complications after HA injections. Possible complications include infection, tissue necrosis, and pseudoseptic arthritis. Pseudoseptic arthritis is severe inflammation at the injection site, and doctors may treat it with NSAIDs or corticosteroids.

Anyone who notices any unusual or severe symptoms following an HA injection should speak with a doctor immediately.

Very limited evidence suggests that HA supplements may help ease osteoarthritis symptoms in some people. For example, a 2014 study reported that a 3-month course of HA supplements eased the symptoms of knee osteoarthritis in people with obesity.

The researchers noted that by the end of the treatment, people had an increased concentration of HA in their joint fluid and a reduction in inflammatory cytokines. However, this was a small study with only 40 participants.

A 2015 study reported that oral HA had similar effects. Among the 72 participants with knee osteoarthritis, those who received oral HA had lower pain scores and improved sleep quality than those in the placebo group. They also used fewer pain medications.

Overall, more large-scale trials are necessary to understand how HA supplements might help with osteoarthritis.

According to the Arthritis Foundation, insurance companies often cover HA injections for arthritis. However, the treatment may require preauthorization, so it is important to check ahead of time.

Additionally, some companies may only cover one series of HA injections every 6 months. If a person needs the injections more often than this, they may not have coverage. Anyone who is unsure can check the policy documents for their plan or speak with an adviser.

The cost of HA injections without insurance can vary greatly depending on location. As a rough guide, they may cost $350–500 per shot.

Hyaluronic acid is a safe and effective treatment for many people with osteoarthritis. It can reduce pain and help lubricate the joints.

The effects of HA injections are temporary, so a person will need to have periodic courses of treatment to maintain the benefits. There may also be some mild pain or swelling at the injection site for a few days afterward.

Oral HA supplements may also be beneficial for people with osteoarthritis, but research on this is still in the early stages.