What Are Salmon DNA and Polynucleotide Injections?

Polynucleotides, marketed as salmon DNA, are purified DNA fragments over 95 percent free of protein, injected into the skin. No polynucleotide or PDRN product holds a Health Canada licence. Both federal product databases return no records, and Health Canada has seized these products from Canadian clinics.

That is the part patients almost never read, so it goes first. The rest of this article explains what the treatment is, what the research shows, and why the Canadian position is what it is.

What are polynucleotides made of?

They are DNA fragments purified from the sperm DNA of salmonid fish, usually chum salmon or salmon trout. The DNA is extracted and purified at high temperature, which recovers an active substance over 95 percent pure with the proteins and peptides inactivated.

You will see two acronyms used loosely. PDRN, polydeoxyribonucleotide, generally refers to shorter chains, with molecular weights under 1,500 kilodaltons and a typical peak around 132 kilodaltons. PN, polynucleotides, generally refers to longer fragments above that threshold. The distinction is not standardised between manufacturers or papers, so treat it as a general rule rather than a definition.

How are they supposed to work?

The proposed mechanism has two parts.

First, the fragments are broken down by enzymes in the tissue into smaller pieces including adenosine, which binds the adenosine A2A receptor. That receptor is involved in resolving inflammation, in angiogenesis, and in fibroblast activity.

Second, the fragments supply nucleosides and nucleotides to what is called the salvage pathway, letting cells reuse those building blocks when making them from scratch is impaired.

Two honest caveats. One study found the effects were reduced but not abolished when the A2A receptor was blocked, which suggests other pathways are involved and the mechanism is not fully mapped. And almost all of this work is preclinical, done in cells and animals rather than in human skin.

Are polynucleotides legal in Canada?

No product containing them is authorized here, and this is not a grey area.

Health Canada's two public databases answer this directly. The Medical Devices Active Licence Listing returns no records for polynucleotide, PDRN, polydeoxyribonucleotide, nucleotide, Rejuran, Plinest or Nucleofill. The Drug Product Database returns no records for the same ingredient and brand terms. Control searches in the same databases return results normally, so those are real absences rather than a broken query.

Health Canada has gone further than simply not licensing them. Rejuran and Rejuran i appear by name on a Health Canada list of unauthorized injectable products seized from a Vancouver clinic, and a PDRN product was seized from a second clinic in Ontario. Health Canada's wording is direct: unauthorized health products have not been assessed for safety, effectiveness and quality, and selling unauthorized health products in Canada is illegal.

The licensing reason is worth understanding. A dermal filler manufactured from animal tissue or its derivatives is classified as a Class IV medical device, the highest risk class, and Class IV devices require review of safety and effectiveness evidence before any licence issues. Salmon-derived polynucleotides are an animal-tissue derivative. No such licence has been granted.

For contrast, within the same databases there are over 30 licensed hyaluronic acid dermal fillers, licensed hyaluronic acid skin boosters, and around eleven licensed platelet-rich plasma processing systems.

Does Defitelio mean PDRN is approved?

This comes up, and it is worth heading off.

There is one polydeoxyribonucleotide authorized in Canada. Defibrotide, sold as Defitelio, holds a drug identification number. It is a prescription treatment for hepatic veno-occlusive disease, a life-threatening liver complication of stem cell transplant. It is not derived from salmon, it is not a skin product, and its authorization says nothing about cosmetic polynucleotide injections.

What is the status in other countries?

Approvals elsewhere are real, and they are narrower than the marketing suggests.

In Italy, Placentex is an authorized medicine whose active ingredient is polydeoxyribonucleotide, with indications that are dystrophic and ulcerative rather than cosmetic. In South Korea, a salmon-derived product has been approved as a cream for wound healing and as an injectable for post-grafting wound repair. Again, wound repair, not cosmetic rejuvenation.

A CE mark under EU medical device rules has been reported in trade press for the Rejuran range. The United States FDA database returns no clearance for polynucleotide or polydeoxyribonucleotide devices.

So the pattern across regulators is that where these products are authorized, it is usually for wound healing, and cosmetic rejuvenation is an off-label extension of that.

How strong is the research?

Small, short, and concentrated in two countries.

A systematic review of randomised trials published in 2026 found seven trials involving 183 participants in total, covering skin rejuvenation, scar prevention and wound healing, and concluded that the evidence base remains limited by small sample sizes, heterogeneous protocols and variable outcome measures. A second review covering nine studies and 219 patients rated them low to moderate quality and called for rigorous high-quality studies to validate effectiveness and safety.

So the entire randomised evidence base for cosmetic use is roughly 180 to 220 patients. For comparison, a single licensed filler goes through larger trials than that before licensing. No serious treatment-related adverse events were reported across those trials, which is reassuring on safety but does not substitute for the regulatory review that has not happened.

How do they compare with PRP and hyaluronic acid?

The three do genuinely different things.

Polynucleotides act through the adenosine receptor and the salvage pathway. PRP works through concentrated growth factors from your own blood, and is covered in detail in our guide to a full PRP course. A hyaluronic acid product works by binding water and providing structure, and is the only one of the three with licensed products in Canada.

On head-to-head data, a small randomised trial of 24 women comparing microneedling with PDRN against microneedling with PRP found a significantly greater reduction in wrinkle scores in the PDRN group, with no difference on a skin hydration index. Twenty-four participants is hypothesis-generating, not conclusive. A review comparing polynucleotide and hyaluronic acid fillers reported greater wrinkle-depth reduction and longer duration for polynucleotide at twelve months.

Those results are interesting. They are not a substitute for a licence.

Who should not have this treatment?

Fish and shellfish allergy is treated as a bar to treatment. The American Academy of Ophthalmology states that polynucleotide injections should not be offered to patients with fish or shellfish allergies. Some clinical reviews use softer wording, noting that fish allergy is driven by protein while the product is purified DNA with proteins inactivated, so the theoretical risk is low.

The reason to keep it absolute in Canada is straightforward. With no licensed product, nobody can verify the protein content of a given vial against a reviewed standard. The safest position is to treat the allergy as a contraindication.

Other contraindications reported in the literature include being under 18, pregnancy and breastfeeding, active or systemic infection, bleeding disorders, autoimmune conditions including lupus and scleroderma, and epilepsy. These come from expert consensus rather than approved labelling, largely because outside Italy there is little approved labelling to draw on.

What should a Montreal patient take from this?

If a clinic in Quebec offers you salmon DNA injections, the useful questions are what exactly is being injected, where it was sourced, and under what authority it is being used in Canada. You are entitled to a clear answer.

The Collège des médecins du Québec requires an in-person medical evaluation before any aesthetic injection and requires a physician to remain accessible for adverse reactions, though it has not published a position on polynucleotides specifically.

Where the goal is skin quality, there are licensed options in Canada with reviewed safety data behind them, and it is worth seeing the full treatment range before pursuing something that regulators here have not assessed.