In popular culture and on social media, you can barely move for mention of ‘salmon sperm’ injections and facials at the moment. (This nickname is actually slightly inaccurate, but I’ll get to that later.) Kim Kardashian is getting them, the Selling Sunset girls are celebrating Galentine’s with them. And, yes, the beauty and aesthetics industries have been abuzz with the power of injectable polynucleotides, with both beauty editors and consumers having been impressed by the results.
After the initial polynucleotide boom, a secondary trend began to emerge on social media: PDRN serums, also acquiring the nickname salmon sperm skincare. And take to TikTok and you'll see that people are, ostensibly, loving said serums. But if there’s one thing I’ve learned about skincare results in my years as a beauty editor, it’s that no topical skincare product can achieve results that are close to those of an injectable treatment—which are the reason so-called salmon and trout sperm-derived treatments really took off in the first place.
So is PDRN a useful addition to our skincare routines, and even on its way to becoming as much of a mainstay as our vitamin C serums and retinoids? Or should we be more sceptical of the hype here? I reached out to two of my most trusted doctor expert contacts, a consultant dermatologist and plastic surgeon, to get their insights.
What is PDRN? Is it actually salmon sperm?
First, some background on PDRN, which stands for polydeoxyribonucleotide. This skincare ingredient is popular in Korea, so it’s not hugely surprising that it’s taken off given the UK beauty macro trend for K-beauty products, as well as the links to polynucleotides.
“It’s derived from certain types of fish DNA fragments, which are typically extracted from the cells within either salmon or trout,” says Dr Ash Soni, plastic surgeon, aesthetic doctor and founder of The Soni Clinic. Note the word “derived” here—The “salmon sperm” nickname stems from the fact that polynucleotides or PDRN are extracted from the spermatozoa of salmon or trout. So while it’s true that these treatments are sperm-derived, nobody is being injected with actual sperm.
Is PDRN the same as polynucleotides?
All that sounds quite familiar and similar to polynucleotides, and it’s true that they usually have the same origin in terms of fish DNA. But the main differences are structural; polynucleotides are longer fragments and have a larger molecular weight than PDRN—which also means the possible benefits vary slightly.
But when comparing PDRN serums and polynucleotides, the application methods also really the two apart. “Injectable polynucleotides are placed into the dermis/subdermis where they act like biostimulatory scaffolding signals,” explains consultant dermatologist Dr Anjali Mahto, founder of the Self London clinic. However, in the case of PDRN skincare, “A topical serum sits on the epidermis, so penetration is far lower.” (PDRN can also be injected, but in the UK polynucleotides seem to be more widely available and the preferred choice for many aesthetic doctors.)
What are the benefits of PDRN serums?
As a skincare ingredient, PDRN does look to have some benefits. “From a science perspective and [in terms of] clinical effectiveness, we know that PDRN are anti-inflammatory, they increase antioxidants, they will regenerate and repair the tissues as well as stimulating that collagen and elasticity,” says Dr Soni. In skincare, it is thought to have some antioxidant benefits and the ability to soothe and hydrate the skin.
However, it’s an area that requires a lot more research. “In theory, it could potentially help repair and calm inflammation,” says Dr Mahto. “But we don’t have robust clinical data yet, especially with regards to topical skincare, so it is still a ‘maybe’. In reality, retinoids, niacinamide, ceramides and sunscreen still have far better data for lines, barrier repair and pigmentation.”
As is true of other skincare ingredients, the level of benefit you can get from a topically-applied PDRN product will be far lower than injectables. As such, “We cannot assume the same benefit, same depth of signalling or same collagen style remodelling [as polynucleotide injections],” says Dr Mahto. She suggests this is similar to the phrase “Botox in a bottle”, one of my beauty editor peeves: “They are not equivalents and they should not be marketed as such. It's a similar argument to when serums claim they can mimic anti-wrinkle injections—something topical just can't compete with an injectable.”
The main issue, Dr Soni points out, is that the molecules are too large to penetrate the skin effectively when applied topically in serum form. To be able to stimulate collagen and elastin, polynucleotides are injected deep into the skin to target the correct receptors.
“The problem with putting this in a serum or a skincare product is you will not get effective penetration deep enough to get the same level of stimulation—or even close to the level of stimulation—that you would get from an injectable product because of current delivery systems,” he explains. “You can’t precisely put it where you want to put it, you’re essentially applying it topically and hoping that some of it will diffuse a little under the surface of the skin.” Any benefits, therefore, would be far more gradual and subtle.
Should I try a PDRN serum?
All this is not to say that there is no place for PDRN serums. More that it's important to bear in mind where some of the hype has come from and that it's a good idea to manage your expectations.
If you want those much talked-about regenerative benefits, have the budget and are comfortable with injections, polynucleotides are the best option. However, this is a treatment that requires multiple sessions and costs several hundreds of pounds. PDRN serums may not hold a candle to the results of polynucleotides injections, but they are also vastly cheaper with more of a "give it a go" price tag.
But the bottom line is: “The hype is definitely riding off the injectable polynucleotide explosion,” says Dr Mahto. “I think it might end up having some benefit in cosmetic skincare when we have better data and better delivery systems, but right now it is still theoretical.”
Dr Mahto’s view is that you would be better off investing in other products if you really want to see a difference in your skin, given the evidence base. “If you have a limited budget and want proven visible outcomes, prioritise sunscreen, prescription retinoids (in the right patient) and azelaic acid, niacinamide and ceramide serums—this is still where the highest yield is,” she concludes.
