We use hyaluronic acid injections to reduce arthritis pain, and Durolane is one of the most widely used. Some reports suggest Durolane has more side effects than other hyaluronic acids — but a recent study challenges that claim. So what are the side effects of Durolane, and is severe pain after a Durolane injection common? And if your knee pain is worse after a Durolane injection, what should you do?

This page focuses on side effects. For how Durolane works, the cost, and the evidence, see our Durolane injection guide; for post-injection care, see what to do after a knee gel injection.

What is Durolane?

Durolane is a type of hyaluronic acid — a substance found naturally in the joint lining, where it lubricates and absorbs shock. Arthritic joints hold less of it, so they lose cushioning. Unlike Synvisc, which is made from egg protein, Durolane is produced through a bacterial process. The molecule is enlarged (high molecular weight) and cross-linked, which makes it more potent and longer-lasting.

How does Durolane work?

Durolane reduces pain in two ways. First, it restores lubrication and shock absorption inside the joint. Second, it binds to the joint lining and reduces the toxic substances that drive arthritis. The larger, cross-linked molecule binds more strongly and breaks down more slowly — which is why Durolane tends to outperform other hyaluronic acids in studies of knee arthritis.

Durolane side effects

swollen knee joint in man with Durolane side effects

Every injection — cortisone, PRP, or hyaluronic acid — carries side effects. Most Durolane side effects are mild.

Common Durolane side effects

  • Mild joint swelling
  • Mild joint pain
  • Muscle stiffness around the joint

These mild side effects affect about 10–20% of people and last only 1–2 weeks. They often need no treatment, though icing or an anti-inflammatory, such as ibuprofen or naproxen, can settle the joint faster.

Interestingly, a recent study suggests these mild effects may not come from the hyaluronic acid itself. When researchers compared Durolane with sterile water in knee arthritis, both caused similar rates of mild side effects — pointing to needle trauma, rather than the gel, as the likely cause.

Rare, severe Durolane side effects

Severe side effects are very rare.

In fewer than 1 in 100 cases, the joint swells with intense pain — an allergic-type reaction some doctors call “pseudo-sepsis”, because it mimics infection. It usually starts the day of the injection, sometimes a few days later, and lasts days to weeks. Occasionally the joint is drained to relieve pressure, or a cortisone injection settles it.

Rarer still is infection, in about 1 in 10,000 cases. The joint swells and is intensely painful to move, often with fever, sweats, and chills. A joint infection needs urgent treatment.

What a new study tells us about severe reactions

A recent review of severe reactions after hyaluronic acid found:

  • Severe reactions usually start after about six hours.
  • They can occur with any hyaluronic acid brand — not just Durolane.
  • They’re more common when the gel is accidentally injected outside the joint.
  • If one occurs, see your doctor. Sometimes watching and waiting is enough; other times, the joint is drained and blood tested to exclude infection. Gout or pseudogout can also cause joint inflammation.

How do we reduce the risk of a severe reaction?

Injecting hyaluronic acid outside the joint — into muscle, tendon, or fat — raises the reaction risk. So most doctors use ultrasound guidance to hit the joint accurately. Missing the joint also makes the gel less effective. So an ultrasound-guided injection both works better and reduces the risk of reaction.

Frequently asked questions about Durolane side effects

Knee pain worse after a Durolane injection — what does it mean?

Pain worsening within a few days is usually a mild reaction. Severe pain and swelling may mean a true reaction. But pain lasting beyond a few weeks is often the arthritis itself, not the injection. If the joint is hot and very swollen, see your doctor to exclude a reaction or infection.

Is Durolane more likely to react than other hyaluronic acids?

Not according to recent evidence. As a high-molecular-weight gel, Durolane may carry a slightly higher reaction rate than weaker products, but the difference is small and the vast majority of reactions are mild and settle quickly. Reactions can occur with any brand.

Durolane vs Synvisc: which is better?

Both are high-molecular-weight hyaluronic acids, but Synvisc is made from egg protein, which increases the risk of allergy. A study comparing them in knee arthritis favoured Durolane at six months.

How long do Durolane side effects last?

Mild reactions last 1–2 weeks. A severe reaction, though rare, can take a few weeks to settle. Anti-inflammatory measures — ice and ibuprofen — speed recovery.

What if the gel was injected into the muscle by mistake?

The body breaks down the hyaluronic acid over time, so long-term problems are unlikely. In the short term, an oral anti-inflammatory helps with the pain and swelling. See your doctor if symptoms are severe or worsening.

How soon does Durolane start working?

Usually within four weeks, sometimes as early as two, occasionally up to six. Don’t judge the injection too early — early soreness is not a sign it has failed. 

Final word from Sport Doctor London about Durolane side effects

Durolane is a safe, effective injection for knee arthritis. Severe side effects are rare and usually settle with simple treatment, and the risk is no higher than with other hyaluronic acid brands. Because reactions are more likely with inaccurate injections, have yours done by an expert under ultrasound.

To book a one-stop ultrasound-guided Durolane injection in London, contact Dr Masci’s team here or call +44 (0) 203 488 0350.

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