What Is PDRN (Salmon DNA)? The Difference Between Injection and Cream

The phrase "salmon DNA" is eye-catching, but PDRN has nothing to do with transferring genetic information. DNA purified from fish milt is used in short fragments. These fragments act in two ways: they stimulate the adenosine A2A receptor on cells and reduce inflammatory signals; and when broken down they supply nucleotides that cells can reuse. This picture comes from laboratory and wound studies. The often-confused polynucleotide (PN) is longer-chained, but there is no standard threshold separating the two, and in publications they are often used interchangeably.

Is injection the same as cream?

No. The same name describes two different worlds.

Injection data are also weaker than expected. A 2026 review lists the small number of randomised studies, small samples, formula differences and the lack of long-term follow-up as limitations. Decisions on procedures such as mesotherapy should be made with your physician.

Why is the evidence so weak for creams?

The central issue is size. In one study, the average weight of the PDRN used reached up to 850 kilodaltons, which is a very large molecule for the skin barrier. The authors themselves leave how it passes as an open question. The most striking new data is this study: in 31 women declaring sensitive skin, a half face was compared over 28 days with a 0,1% PDRN eye cream and a 0,1% retinol cream. The crow's feet area and number decreased by 20-23% on the PDRN side and by 6-7% on the retinol side.

It looks impressive, but keep in mind:

• The comparison is with retinol, not with placebo; there is no arm with an unmedicated base cream.
• In the measurement of passage in live human skin, done on a single volunteer, the relative passage at 24 hours was 3,06%.
• The authors themselves say that the early changes over 28 days may stem from moisture and swelling.
• Some of the authors are linked to cosmetic companies, and the PDRN was supplied by a manufacturer.

The PDRN percentage, molecular size and purity are unknown in most products on the label. So even if used for at least 6 weeks, there is no basis to expect an injection result from a cream.

When should you consult a doctor?

• Fish or shellfish allergy: Even if production involves purification, this allergy is listed among the situations where injection should not be done. A case of hypersensitivity after a fish-derived polynucleotide injection has also been published. The risk is unknown for cream, but if you have allergies, ask before use.
• Injection plan: Should be done only by a physician, with a licensed product. Do not inject an ampoule bought online at home.
• Needle roller: Do not try to send a cosmetic serum under the skin with microneedling; these products are not made for this, and there is a risk of infection or an unwanted tissue reaction.
• After a procedure: If swelling, pain, heat or fever does not subside, see the physician who performed it without delay.
• Pregnancy and breastfeeding: Do not have an injection during this period; for the cream too, consult your doctor first.

If PDRN comes up for wound care or chronic wounds, that is entirely the physician's domain. When trying a new cream, test it on the inner arm or elbow crease, twice a day, for 7-10 days.