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Ep 29: There's Something Fishy About PDRN - The Truth About Salmon Sperm in Skincare


Unless you live under a rock, you’ve probably heard about the newest ingredient sweeping the globe: PDRN. In the last few years, it has become incredibly popular in skincare; it seems like every day, a new PDRN product is launched. But what is PDRN, how does it work, and why is it being advertised as the newest miracle ingredient? Today we’re going to explore the history, science, and hype behind this ingredient, and determine whether it’s worth your time and money. 


What is PDRN?


PDRN is short for polydeoxyribonucleotide, and it’s a mixture of DNA pieces that range from roughly 50 to 2,000 kilodaltons (which is just a really small unit of measurement). It’s typically extracted from salmon or trout sperm. The main reasons for this is that 1) there’s not very much present in human placentas to begin with, and 2) there are a lot of ethical issues with taking things from human placentas, which is why we switched to salmon as a substitute. There’s a whole purification process (no, you are not putting pure salmon sperm on your face), but basically they collect the semen, separate the DNA from the semen, and then fragment it. It’s 95-98% genetically similar to human DNA, which means it can function as a building block to repair our cells without triggering an immune response. 


When did PDRN become popular?


PDRN originated in Italy in the 1980s, and was considered a breakthrough in wound healing and regenerative medicine. Like I said, they first used it from human placentas, but they switched to salmon. In 2008, the Korean FDA approved a PDRN-based injectable, known as Rejuran or “salmon DNA injection” for skin rejuvenation and repair. However, as of 2026 it is not approved by the United States FDA. Interest has spiked a ton within the last year, and it keeps growing, leading PDRN to be one of the most popular skincare ingredients right now. 


Topicals vs Injectable Studies


Okay first I must shout out the Chemist Confessions podcast; they found some really great studies by filtering out the relevant science, and in their episode they go more in-depth about each study. I highly recommend listening to their episode and checking out their blog post, they did a lot of work to find good evidence about PDRN!


Most of the evidence around PDRN has been done with injectables; but even then, not all of the studies have been good studies. One of the main studies that’s referenced is a study testing PDRN’s effectiveness on diabetic foot ulcers. They fond that 37.3% of the PDRN-treated group healed fully within 8 weeks, compared to 18.9% in the placebo group. And that sound great, but you have to keep in mind that they were injecting PDRN into the foot ulcers… that’s pretty different than slapping on a moisturizer with PDRN before bed. 


One topical study done in 2004 showed that applying topical PDRN to skin graft sites helped the wounds heal faster; the PDRN group epithelialized, or became covered with tissue, in 12.5 days, versus 24.45 days for the group that didn’t have anything applied. However, skin graft skin is very different from healthy skin, so you really can’t compare the two. 


Penetration is the biggest issue


When it comes to pretty much any skincare ingredient, penetration is the biggest issue. We’ver talked about it before, but there’s this rule called the 500 dalton rule, which says that molecules larger than 500 daltons can’t pass through our skin barrier. Molecules below 500 daltons are more likely to penetrate into the skin; anything bigger than that typically just sits on the surface. They can still provide some benefits, but obviously penetration is usually the goal in skincare. 


PDRN is a mixture of a bunch of different fragments that range anywhere from 50 to 1,500 kilodaltons - for reference, that’s up to 1.5 million daltons. The smallest fragments are around 50,000 daltons, which last time I checked is a bigger number than 500 (the maximum size for skin penetration). Basically PDRN is way way WAY too big to penetrate into the skin. Yes, there are technologies that exist to help these big molecules penetrate better, but PDRN on its own physically can’t penetrate the skin barrier. 


The regulatory gap with PDRN


In the US, the FDA classifies PDRN as a cosmetic ingredient; this means that no drug claims can be made. If you’ll remember, a drug is anything that alters the structure or function of your body. A lot of companies talk about the regenerative effects of PDRN (remember those like two studies we read about?) but those studies come from injectables. When a topical product starts borrowing claims from studies about injectables, they can get into some sketchy territory, because it can create implied medical claims. Companies have to be careful about the wording they use surrounding their products; they can’t say that PDRN “repairs DNA” or “heals wounds”, but they can say things like “supports regeneration” or “enhances natural repair” to keep it within cosmetic boundaries. 


I’ve definitely seen some PDRN products that cross over into the sketchy territory when it comes to the claims they’re making. I won’t list any companies or products in particular, but maybe keep an eye out for that when you’re looking at PDRN products. If the claim sounds too good to be true, it probably is - and it might be illegal. 


Plant-based PDRN


Another marketing angle is plant-based PDRN. It’s advertised as a vegan alternative to PDRN; because, you know, PDRN is animal-derived. SIde note, I feel like most people have a negative view of animal testing and animal-derived ingredients, so I’m kind of surprised that PDRN has gotten as big as it has. I guess marketing will really do that to you. 


Anyway, plant-based PDRN is basically the biggest marketing gimmick. It’s marketed as PDRN derived from plants like green tea, ginseng, and rose, but plants don’t produce DNA that works anywhere near salmon DNA. Also, the whole reason salmon DNA is being used in the first place is because it so closely mirrors human DNA - plants don’t, so even if PDRN was a miracle ingredient, it would only work well because it’s derived from salmon. The ingredients in those plant-based products are usually things like polyphenols, antioxidants or ingredients with soothing benefits - but they are definitionally not PDRN. 


Supply chain issues


As we’ve mentioned, PDRN is derived from salmon semen, and it’s pretty hard to obtain because these fish only spawn during breeding season, which can make it expensive to get. As far as I know, brands aren’t using synthetic PDRN in their products - so if they are adding PDRN to every single serum they have, but they’re working with a supply that is seasonal and therefore constrained, are they actually putting the PDRN in the product at an efficacious concentration (if there even was one)? 


What PDRN might be good for


Now, I don’t want to be all doom and gloom about PDRN, because even though we don’t have the studies to back up a lot of the claims companies are currently making, that doesn’t mean that it doesn’t work. One of the most reliable studies we have is on skin graft skin, which is compromised; so I do think there could be a case for saying that PDRN could help with injured skin or post-procedure skin, to help soothe and possibly accelerate the healing process. So in theory it could work for in-office procedures like microneedling or laser treatments to help decrease healing time. Do I know that for sure? Absolutely not. But I do think there could be a place for PDRN in cosmetics, I just don’t like how companies are taking this ingredient and absolutely running for the hills with it. 


So based on what we know, is PDRN actually legit? 


No… at least, not really. It seems to be an ingredient that’s marketed as doing it all - as the Chemist Confessions podcast put it, it’s like unicorn tears. Every day a new claim about PDRN pops up, and it kind of feels like that’s happening because nobody really knows what it does; we simply don’t have enough studies behind it. 


I personally feel like PDRN is just the trendiest ingredient right now, and something else is going to come along and take its place. Unless well-done studies come out about PDRN and its efficacy can be proven, I’m going to stick to ingredients that have been proven to work, such as retinol, Azelaic Acid, Vitamin C, etc. PDRN seems fun and it’s certainly marketed as a miracle, but until there’s legit science backing it, I’m just not convinced. 


That being said, there is a lot of value to real-world experience; we’ve talked about how important reviews are, and how sometimes something can work for you even if there isn’t science behind it. To truly put PDRN to the test, we’ve partnered with TNT on Instagram over at @thisnotthatofficial; on her account she tests a TON of products, and she has certainly tested her fair share of cosmetics with PDRN. She shared her list of products with us, and we’re going to dig into the science behind them and see if our assessment of the products matches up with her experience. Go check out her page to see what we find!


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