A “salmon sperm” injection for your injured tendon? PDRN therapy explained

Maryke Louw
2 days ago
6 min read

I really struggled to keep a straight face when I heard that one of our patients had had a “salmon sperm” injection for their tendonitis. But then I became curious and had a look at the research, and it turns out that it is actually a promising treatment – called polydeoxyribonucleotide (PDRN) therapy in medical circles. Here’s the state of play with regards to PDRN injections and tendon injuries.

Remember, if you need help with an injury, you're welcome to consult one of our physios online via video call.

A person holding a salmon and the words: Salmon sperm injections...do they work?

In this article:

Where does the salmon sperm come from?
Proven uses of PDRN
What about PDRN for tendon injuries and plantar fasciitis?
Is a PDRN injection safe?
Our recommendation
How we can help

Where does the salmon sperm come from?

OK, I’ll be honest – one of the first questions that popped into my head when I heard about this was, “How do they collect the salmon sperm?” It turns out that the process is reassuringly simple and clean.

Polydeoxyribonucleotide (PDRN) therapy uses DNA extracted from the sperm of farmed salmon (usually chum salmon or salmon trout) that are killed anyway for food.

💡 The sperm is purified and sterilized to isolate DNA fragments while removing proteins or peptides that could trigger immune reactions. The result is a clear, DNA-rich solution, so nobody is being injected with actual salmon sperm.

When injected, these DNA fragments are thought to stimulate tissue repair. Scientists believe PDRN works by activating the body’s cellular healing pathways – for example, it interacts with specific receptors that increase blood flow and growth factors at the injury site, helping tissues regenerate more effectively.

In short, a “salmon sperm” injection is believed to be a regenerative shot packed with DNA, aimed at kick-starting recovery in injured or damaged tissues.

But does it actually work? 🤷‍♀️

Proven uses of PDRN

PDRN injections have been studied and successfully used in several medical areas. In wound care especially, PDRN has been shown to help tissue regenerate when standard treatments alone weren’t enough.

Chronic wound healing (e.g. diabetic foot ulcers).
Peripheral circulation problems: PDRN has been used to improve blood flow in areas where circulation is poor, helping damaged tissue heal.
Skin rejuvenation in dermatology: PDRN has made a splash in the cosmetic world as the so-called “salmon DNA” skin treatment. Doctors inject it into the skin to improve hydration, elasticity, and texture – in clinical and “beauty treatment” situations.

Its success in these domains is what led researchers to ask: could the same PDRN injections help repair injured tendons, ligaments, or other musculoskeletal tissues?

What about PDRN for tendon injuries and plantar fasciitis?

Tendon and plantar fascia injuries – from acute tears to chronic tendinopathies – are notoriously stubborn to heal. Traditional care like physiotherapy, eccentric exercise, or shockwave therapy can help, but often the recovery is slow and incomplete. This is where the salmon-sperm-derived PDRN injections have sparked interest.

Over the last few years, a number of studies on animals and humans have tested PDRN for tendon and plantar fascia injuries.

Tendon injuries

PDRN has been tested on various tendon issues – and although studies are still relatively small, the results have been promising.

Two reviews of the available research have shown reduced pain and improved function in patients with common tendon ailments who received PDRN injections. These include:

Achilles tendinopathy and tears: In animal experiments, PDRN injections sped up healing of a ruptured Achilles tendon – reducing inflammation and improving the quality of new tendon tissue. On the human side, case series have noted pain reduction in chronic Achilles tendinopathy after a course of PDRN shots.
Tennis elbow (lateral epicondylitis): Small studies indicate PDRN might help this chronic elbow tendon pain. Patients with epicondylitis experienced significant pain relief after PDRN injections, similar to improvements seen with platelet-rich plasma in some cases.
Rotator cuff tendinopathy: One pilot study reported that PDRN injected into the shoulder joint led to “remarkable pain reduction and functional recovery” in people with rotator cuff tendinopathy. Pain scores dropped substantially over a few weeks, and shoulder movement improved.
Pes anserine tendinopathy/bursitis: The pes anserine (inner part of the knee) is another site of tendon-related pain often seen in runners or people with arthritis. PDRN has been tried here too, with reports of symptom improvement.

👉 This all sounds positive on the surface, but it’s important to point out that all of these studies were quite small and not of very high quality.

Plantar fasciitis

This painful heel condition has been a key focus.

One randomized trial in chronic plantar fasciitis found that PDRN injections provided significantly more pain relief after twelve weeks than for people who were injected with a placebo (fake) substance.

💡 This study is of better quality than the tendon research mentioned earlier, so it carries a bit more weight in my opinion. However, even though it suggests that PDRN might be a viable option for persistent plantar fasciitis, we need several studies to confirm these results to know that they are actually legit.

Click this link to download the Exakt app which contains research-based rehab plans for runners. — I designed the rehab plans in the Exakt app. Use my name to claim your discount: MARYKE 🙌

Is a PDRN injection safe?

One of the appealing aspects of PDRN therapy is that it appears to be quite safe and well-tolerated. In the clinical studies on tendon and plantar fascia injuries, no serious adverse effects have been reported.

Unlike some medications, PDRN doesn’t provoke systemic side effects like stomach upset or elevated blood sugar, because it works locally at the injection site (and the injected DNA fragments are eventually broken down naturally by the body).

Of course, with any injection, there are general risks: slight pain, redness, or bruising at the needle site, and a very small risk of infection.

Our recommendation

So, should you try a salmon sperm (PDRN) injection for your tendon or plantar fascia injury?

Our stance is one of cautious optimism. The science so far is encouraging – these injections could potentially speed up healing in stubborn tendon injuries or plantar fasciitis where other treatments haven’t fully worked.

That said, the research is still in early stages. We do not yet have large clinical trials proving that PDRN injections are the magic bullet for tendon tears or chronic tendinopathy.

These injections are also not cheap – a course can add up to £500+ in total.

💡 Therefore, we do not currently recommend PDRN injections as a first-line treatment for tendon or plantar fascia problems.

If you have a chronic injury that isn’t improving despite doing all the right things, and you’ve consulted with a specialist who has experience with PDRN, it could be something to consider – but with managed expectations. Essentially, you’d be volunteering to try a novel therapy that might help or might do nothing, and will cost you out of pocket.

For most patients, the foundation of recovery should remain the proven therapies which consists of a structured plan combining:

An appropriate amount of rest,
exercises that progressively load and restore the tendon or plantar fascia’s strength and endurance,
and, depending on the specific case, adjuncts like specific shoes or insoles or shockwave therapy.

👉 We have written detailed articles discussing the best research-based treatments for these injuries which you can find by selecting the relevant topic on this page.

How we can help

Need more help with your injury? You’re welcome to consult one of the team at SIP online via video call for an assessment of your injury and a tailored treatment plan.

We're all UK Chartered Physiotherapists with Master’s Degrees related to Sports & Exercise Medicine or at least 10 years' experience in the field. But at Sports Injury Physio we don't just value qualifications; all of us also have a wealth of experience working with athletes across a broad variety of sports, ranging from recreationally active people to professional athletes. You can meet the team here.

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About the Author

Maryke Louw is a chartered physiotherapist with more than 20 years' experience and a Master’s Degree in Sports Injury Management. Follow her on LinkedIn and ResearchGate.