What Are Polynucleotides? Salmon-DNA (PDRN) Explained

The word polynucleotide appears on more and more treatment menus, often alongside the term PDRN and the shorthand "salmon DNA." For practitioners fielding patient questions, it helps to be clear on what these ingredients actually are and how they are thought to work.

PN and PDRN: The Terminology

A polynucleotide is simply a chain of nucleotides — the same molecular units that make up DNA. In aesthetics, "polynucleotides" (PN) refers to purified fragments of DNA used as an injectable.

PDRN — polydeoxyribonucleotide — is a specific, defined length-range fraction of these fragments that has been the subject of the most published research. In everyday clinic language the two terms are frequently used interchangeably, though PDRN is best understood as a particular, well-characterised subset of the broader polynucleotide category.

Where the DNA Comes From

The DNA used is most commonly extracted from the sperm cells of salmon or trout. These sources are chosen deliberately: their DNA sequences share a high degree of similarity with human DNA, which supports biocompatibility and a low likelihood of immune reaction.

The extracted material is then put through a rigorous purification and sterilisation process. The aim is to remove proteins and other cellular material — the parts most likely to provoke a reaction — leaving behind purified DNA fragments. The quality of this purification is one of the factors that distinguishes serious products in the category.

How They Are Thought to Work

Rather than adding volume, polynucleotides are understood to act on the skin's biology through several complementary routes:

• Fibroblast stimulation — encouraging the cells responsible for producing collagen and elastin
• Angiogenesis — supporting the formation of small blood vessels, improving local oxygen and nutrient supply
• Antioxidant and anti-inflammatory activity — helping to calm the tissue environment
• Hydration — the gel itself holds water within the dermis, acting as a temporary scaffold

Together these effects are described as "bioregeneration": creating conditions in which the skin repairs and renews itself over a course of treatment.

What Polynucleotides Are Not

It is worth stating plainly, because patients frequently confuse the categories: polynucleotides are not dermal fillers. They are not designed to project tissue, sculpt contour or restore lost facial volume. A patient whose concern is a deflated cheek or a defined jawline needs a filler or a biostimulator; a patient whose concern is thin, crepey, dull or fatigued skin is a candidate for polynucleotides.

The Fish-Allergy Consideration

Because the active material originates from fish DNA, a history of fish allergy is directly relevant to patient screening and should be part of the standard pre-treatment consultation, distinct from the questions typically asked before a hyaluronic-acid treatment.

The Takeaway

Polynucleotides are highly purified DNA fragments — usually of salmon or trout origin — injected to support the skin's own regenerative processes rather than to add volume. Understanding the source, the purification and the mechanism makes it far easier to set accurate patient expectations and to place the treatment correctly within a plan.

See the polynucleotide range, or read the fuller 2026 guide to polynucleotides.