Do polynucleotide or salmon DNA facial treatments actually work?

Polynucleotides (also known as salmon DNA injections, or sold under brand names such as REJURAN) are injected into the skin and are said to stimulate skin repair, reduce wrinkles, and improve skin texture. That sounds promising, but the research is currently limited and has considerable methodological shortcomings.

For the under-eye area and crow's feet, there are small observational studies and a prospective study in 42 patients that showed improvement up to six months after treatment. Patients were generally satisfied, and side effects were minimal. However, none of these studies included a placebo group, so it is unclear how much of the effect is attributable to the treatment itself and how much to the placebo effect or the passage of time.

The most randomised study, on crow's feet in 218 participants, was later found to have been retracted. That means its results must be considered void. For facial redness and enlarged pores, there are no clinical trials; the only available data come from surveys of cosmetic physicians. Between 77% and 90% of them rated the treatment as effective, but physician opinions are not clinical evidence. In addition, several authors of those studies had a binding relationship with the manufacturer of the product, which undermines the independence of those findings.

For scars and burns, there are isolated case reports without a control group. And although a review article suggests that polynucleotides as an adjunct to another treatment (radiofrequency microneedling) may offer additional benefit, the contribution of polynucleotides specifically cannot be isolated.

In short: for the under-eye area and fine lines, there are cautious indications that the treatment has some effect, but without well-controlled research it remains uncertain how large that effect is. For the other applications, the evidence is even thinner.