Hyaluronic acid injections into the joint: who benefits

Hyaluronic acid injections into the joint are one of the most debated treatments for osteoarthritis. Some patients notice clear relief, others no effect at all, and international guidelines disagree. Let us look honestly at what is known about the benefit of these injections, who they may suit and what to expect from them.

1. What hyaluronic acid is and why it is injected

Hyaluronic acid is a natural component of joint fluid and cartilage. It is what makes joint fluid thick and springy: it lubricates the joint surfaces and cushions load.

In osteoarthritis there is less hyaluronic acid in the joint, and its molecules are shorter. The joint fluid loses its thickness and the cartilage is less protected. The idea behind injections into the joint (called viscosupplementation) is to restore these properties. Hyaluronic acid also seems to reduce inflammation in the joint and act on nerve endings, easing pain.

2. Does it help knee osteoarthritis?

The short answer: it helps, but the average effect is small, and researchers argue about how noticeable it is for the patient.

• In an overview of 22 systematic reviews, 20 found a statistically significant reduction in pain and improvement in knee function compared with placebo.
• But when only the highest-quality studies are counted, the difference from placebo becomes very small by some estimates.
• The effect is not immediate: it usually develops 5–13 weeks after the course, peaks at about 2 months and can last up to six months.

Importantly, the basis of osteoarthritis treatment is therapeutic exercise and losing weight if you are overweight. Hyaluronic acid injections do not replace them.

3. Why the guidelines disagree

The disagreement comes from which studies the experts included and how they judged whether a small effect matters to patients.

4. Who injections may suit

Hyaluronic acid injections are usually discussed when:

• knee osteoarthritis keeps causing problems despite exercise and weight loss;
• anti-inflammatory tablets do not help or cannot be taken — for example, because of stomach, kidney or heart disease;
• there are other conditions that make other treatments undesirable.

The decision is made together with your doctor, weighing the expected benefit, the cost of the course and the alternatives.

5. Other joints

• Hip. Controlled studies have not shown benefit over placebo; the American College of Rheumatology strongly recommends against these injections for hip osteoarthritis.
• Shoulder. In an analysis of 15 studies (more than 1,000 patients), injections reduced pain, including compared with steroid injections. A possible role is when treatment options are limited.
• Base of the thumb. The evidence is weak; the American College of Rheumatology leans against.
• Ankle. There is little good-quality data.

6. How products differ

Products differ in the length of their molecules (low, medium and high molecular weight), whether the molecules are “cross-linked”, and the regimen — a single injection or a course of 3–5 weekly injections.

• High-molecular-weight and cross-linked products stay in the joint longer, but they have not convincingly been shown to be better than others.
• A single injection and a course of several did not show a clear difference in studies.
• Cross-linked products more often cause a marked inflammatory reaction after the injection (see below).

7. Compared with steroid injections and PRP

• Steroids (glucocorticoids) relieve pain faster — the effect peaks at 2–4 weeks but wears off by about week 6. Hyaluronic acid works more slowly but for longer: at 6 months and beyond its results are better.
• Platelet-rich plasma (PRP), according to several analyses of randomised trials, reduces pain and improves knee function at 6–12 months better than hyaluronic acid, with similar safety.

8. Side effects and contraindications

Overall, the injections are well tolerated. Mild side effects occur in 3–20% of patients:

• most often — pain and swelling at the injection site, fluid in the joint; these usually settle on their own within 1–3 days;
• an acute inflammatory reaction — 1–3 days after the injection the joint suddenly swells and hurts, although there is no infection. It is more common with repeat injections and with cross-linked products. It must be told apart from an infection — with these symptoms, see a doctor straight away;
• rarely — a flare of crystal arthritis; joint infection is a very rare but serious complication, which is why the injection is done under strictly sterile conditions.

Contraindications: infection in the joint or on the skin at the injection site, and allergy to the product. If you are allergic to egg or chicken protein, tell your doctor: some products are made from chicken combs.

9. Hyaluronic acid tablets and creams

There is no convincing evidence of benefit. Studies are few, small and short, and the main unresolved question is whether hyaluronic acid from a tablet reaches the joint at all. No guideline recommends these supplements for osteoarthritis, and they do not replace treatment.

Disclaimer: This article is for information only. Whether hyaluronic acid injections suit you is decided by your doctor after an examination.

Sources

1. Kolasinski SL et al. 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee. Arthritis & Rheumatology, 2020.
2. Arden NK et al. Non-surgical management of knee osteoarthritis: comparison of ESCEO and OARSI 2019 guidelines. Nature Reviews Rheumatology, 2021.
3. Bruyère O et al. Effects of Intra-Articular Hyaluronic Acid Injections on Pain and Function in Patients With Knee Osteoarthritis: An Umbrella Review. Maturitas, 2025.
4. Cao Y et al. Quantitative Analysis of the Efficacy and Associated Factors of Intra-Articular Hyaluronic Acid With Respect to Osteoarthritis Symptoms: A Model-Based Meta-Analysis. Osteoarthritis and Cartilage, 2025.
5. DeMoya CD et al. Advances in viscosupplementation and tribosupplementation for early-stage osteoarthritis therapy. Nature Reviews Rheumatology, 2024.
6. Familiari F et al. Efficacy of Intra-Articular Injections of Hyaluronic Acid in Patients With Glenohumeral Joint Osteoarthritis: A Meta-Analysis. Journal of Orthopaedic Research, 2023.
7. Jawanda H et al. Platelet-Rich Plasma, Bone Marrow Aspirate Concentrate, and Hyaluronic Acid Injections Outperform Corticosteroids at a Minimum of 6 Months for Knee Osteoarthritis: A Network Meta-Analysis. Arthroscopy, 2024.
8. Belk JW et al. Platelet-Rich Plasma Versus Hyaluronic Acid for Knee Osteoarthritis: A Meta-analysis of Randomized Controlled Trials. American Journal of Sports Medicine, 2021.
9. Honvo G et al. Safety of Intra-articular Hyaluronic Acid Injections in Osteoarthritis: A Systematic Review and Meta-Analysis. Drugs & Aging, 2019.