Rejuran (PDRN) Injections Explained: How Salmon-Derived DNA Wakes Up Your Skin's Repair System

Injecting salmon DNA into your face sounds like something straight out of a sci-fi skincare ad — and yet, here we are. What began as a Korean aesthetic staple has been quietly crossing into mainstream Western clinics, and patients are asking about it at consultations with increasing frequency. The questions tend to be consistent: Does this actually work? How is it different from fillers or Botox? What does salmon DNA actually do inside the skin? And is it right for me?

The core ingredient is PDRN — polydeoxyribonucleotide. It's a mouthful, but the science behind it is more grounded than the name suggests. This isn't a trend built on hype alone. There's a meaningful body of mechanistic data and clinical research behind it that's worth understanding on its own terms. Let's walk through where that evidence comes from, how much weight you can actually give it, and who tends to respond well — and when.

What Exactly Is a Rejuran Injection?

All the products shown above belong to the same family. Rejuran is the brand name for a line of PDRN-based injectables developed by South Korea's Pharmaresearch. The active ingredient — PDRN — is extracted from the sperm cells of salmon or trout: short, purified fragments of DNA formulated for injection into the dermis.

PDRN and PN (polynucleotide) are often used interchangeably in clinic settings and online, which causes real confusion. Both originate from the same salmon DNA source, but PDRN refers to the shorter-chain fragments that drive most of the receptor-level pharmacological action, while PN refers to longer chains that serve more of a structural, water-binding role in the dermis. PDRN is effectively the active signaling molecule; PN is its longer, more scaffolding-oriented counterpart.

Where it fundamentally parts ways with fillers — products like Juvederm or Restylane — is in mechanism. A filler physically fills a hollowed space, adding volume where tissue has been lost. PDRN doesn't introduce structural material. Instead, it signals your own skin cells to produce collagen and to grow new microvessels. Rather than packing material in from the outside, it's closer to flipping an internal repair switch. That's precisely why results don't appear the same day — they build gradually over weeks as the biological response matures.

The Rejuran line includes several product variants — Healer, HB, Eye (i), and S — each calibrated for different molecular weights and tissue targets. The same PDRN molecule is also used in pharmaceutical-grade wound care products; same ingredient, different formulation and regulatory classification depending on the application. PDRN breaks down naturally over time into nucleotide units that are recycled by the body. Because the source is a fish species, fish allergy is a relevant pre-treatment consideration — we'll return to that.

What's Actually Happening Inside Your Skin?

The graph above shows a lab study where human dermal fibroblasts — the cells responsible for producing collagen — were exposed directly to PDRN at increasing concentrations for 48 hours. The 100% baseline represents untreated cells. As PDRN concentration climbed from 12.5 to 200 µg/mL, cell proliferation rose steadily, reaching roughly 130% at the highest dose. More PDRN, more active cell division.

The mechanism runs through the adenosine A2A receptor on cell surfaces — essentially a molecular on-switch. When PDRN binds to this receptor, fibroblasts activate and begin producing collagen. At the same time, vascular endothelial growth factor (VEGF) is released, stimulating the formation of new microvessels. More capillaries means better nutrient and oxygen delivery to the tissue — a real upgrade for skin that's been chronically sun-damaged or starved of circulation.

There's also a salvage pathway worth noting: the fragmented DNA isn't simply discarded. It's absorbed and recycled as raw material for the body's own nucleotide synthesis. You're not just delivering a signal — you're also supplying building blocks.

On top of that, PDRN has demonstrated anti-inflammatory properties that work in parallel with the regenerative effects. For skin that's been sensitized by UV exposure, acne, or repeated procedures, this means regeneration and calming tend to happen together. That combined effect is often what patients are describing when they say their skin "feels alive again" after a treatment series.

Does It Actually Stimulate Collagen Production?

Understanding cell activation is useful — but does it translate to measurable collagen production? The graph above shows data from an animal wound model comparing collagen levels in PDRN-treated versus untreated tissue at day 7. With the control group set at 1.0×, type I collagen in the PDRN group measured 1.36×, and type III collagen reached 3.07×. Both bars clear the baseline by a meaningful margin.

The type III result is worth unpacking. Type III collagen is the immature, early-response collagen that appears first during tissue repair — it's later remodeled into the denser, mechanically stronger type I matrix. A nearly threefold increase in type III signals robust activation of the early repair cascade, suggesting that the regeneration process is being genuinely accelerated rather than just mildly nudged.

The effect is also bidirectional, not just additive. A cell study by Shin et al. (2023) found that PDRN activates ERK signaling in fibroblasts to upregulate both type I and type III collagen synthesis while simultaneously downregulating matrix metalloproteinases (MMPs) — the enzymes that break collagen down. Build more, break down less. Collagen is in constant turnover throughout life; as we age, the balance tips progressively toward degradation. PDRN appears to shift that balance back.

One honest caveat to state clearly: the data above is preclinical — cell cultures and animal models. Large-scale human studies directly measuring dermal collagen through biopsy are still relatively sparse. The mechanistic direction is well-established; what the clinical studies reviewed next attempt to quantify is the magnitude of that effect in live human skin.

How Much of the Evidence Is Actually Solid?

PDRN's most rigorous clinical data doesn't come from aesthetics — it comes from wound care. The graph above shows results from a double-blind, randomized, placebo-controlled trial in patients with diabetic foot ulcers, one of the most treatment-resistant wound types in medicine. At 8 weeks, complete wound closure occurred in 37.3% of the PDRN injection group versus 18.9% in the placebo group — nearly double (Squadrito et al., 2014). In the same trial, the rate of wound re-epithelialization was 82% in the PDRN group versus 49% in placebo, and median time to full closure was 30 days compared to 49 days.

What gives this study real weight is its design. With 216 participants and genuine blinding on both sides — patients and clinicians unaware of group assignment — this is a result that cannot easily be attributed to expectation or placebo effect. A separate meta-analysis pooling data from multiple trials in knee osteoarthritis also found consistent pain reduction with PDRN injections.

The conceptual bridge to aesthetics is that the biological mechanism is identical. The A2A receptor pathway that heals diabetic wounds and calms inflamed joints is the same one being activated when Rejuran is injected into aging or photo-damaged skin. The tissue targets differ; the underlying signaling does not.

That said, something deserves to be stated plainly: robust, large-scale randomized trials specifically for aesthetic skin rejuvenation are still catching up to the wound care literature. Smaller aesthetic studies show consistent positive trends, but the 200-plus-patient double-blind design that exists in wound healing hasn't yet been replicated at scale for cosmetic indications. That gap is narrowing — but knowing where the evidence is strongest matters when you're deciding how to invest in a treatment.

So Does It Work for Skin and Acne Scars?

Looking at the aesthetic-specific data: the graph above shows scar score improvements from a 16-week acne scar study. PDRN alone improved scores by 6.1 points; botulinum toxin alone improved by 9 points; the combination of both delivered the strongest result at 12 points (Park et al., 2025). Notably, PDRN alone showed the smallest individual gain — which is actually informative. It suggests PDRN functions more as a synergist than a standalone solution, amplifying outcomes when layered with other treatments rather than replacing them.

The caveat is real: this was an open-label study with 17 participants. Firm conclusions from a sample that small aren't possible. Other small-scale studies examining skin texture, pore size, and elasticity generally point in a positive direction, but the variation in methodology makes them hard to aggregate into a clean summary. One wrinkle study tracking fine lines found the greatest depth reduction between weeks 8 and 10, with partial regression toward baseline by week 18 — reinforcing that results don't lock in permanently after one session and that continued treatment is part of maintaining them.

The practical takeaway is to calibrate expectations honestly. PDRN injections are not a single-session dramatic transformation. They're closer to a progressive treatment course that improves skin quality over time — texture, tone, superficial scarring, dullness. If the goal is restoring lost facial volume or reshaping a contour, a structural filler like Juvederm Voluma or Restylane Lyft is the more direct tool. If the primary concern is significant skin laxity, energy-based devices or lifting procedures are better matched. PDRN's strength is overall skin quality — and patients who understand that clearly going in consistently report higher satisfaction.

Who Is the Best Candidate?

In practice, certain presentations tend to respond particularly well. Patients managing residual superficial acne scarring, enlarged pores, or chronically rough skin texture are strong candidates. Because PDRN works by activating dermal regeneration from within rather than ablating or resurfacing from above, it addresses skin quality at a different level than lasers — and often works well alongside them rather than instead of them.

Fine lines, dull or dehydrated-looking skin, and a general loss of radiance are also well-matched targets. The under-eye area is a frequently treated zone: the skin there is the thinnest on the face and among the most delicate to manage. For vascular dark circles — the bluish discoloration caused by visible blood vessels beneath thin skin, rather than by pigment — PDRN's microvascular stimulation can help, as improved circulation and a denser dermis over time may reduce the show-through effect. Pigment-based, brownish discoloration responds to a different set of treatments entirely; a clear differential before treating dark circles is essential. Sun-damaged skin, chronically reactive complexions, and patients in their late 30s through 50s noticing simultaneous collagen loss and elasticity decline are also well-positioned for this approach.

Being equally direct about limitations matters. Significant volume loss in the cheeks or midface is better addressed with a structural filler. Deep rhytids and true skin laxity are better handled by resurfacing lasers, radiofrequency, or lifting procedures. PDRN isn't competing with those treatments — it's more of a foundation-layer intervention that improves skin quality and can make the results of other procedures last longer and look better.

When Will You See Results — and How Long Do They Last?

The most common question in consultation: when will I actually notice something? The straightforward answer is that PDRN injections are not an instant-gratification procedure. The biology takes time — fibroblasts need to activate, collagen needs to be synthesized, microvessels need to mature and stabilize. Most patients begin perceiving a change somewhere around weeks 4 to 6. Results typically peak around months 2 to 3, then gradually taper over the following 4 to 6 months.

The sequence in which changes become noticeable is worth knowing in advance. Skin texture and a luminous, hydrated quality tend to come first. Structural improvements — scar remodeling, elasticity gains — follow more slowly. Framing this as a gradual arc over one to two months rather than an overnight shift makes a significant difference in how patients experience the process.

Individual response varies more than many patients expect. Two people with similar presentations completing the same number of sessions can see meaningfully different outcomes — one responding clearly and early, another more slowly. It's generally more informative to complete a full treatment series before making a definitive judgment on efficacy. A standard protocol is 3 to 4 sessions at 4-week intervals, which allows collagen and vascular changes to accumulate and compound into a more durable result.

Sun protection turns out to be more than standard aftercare advice in this context. UV exposure is a primary driver of collagen degradation — consistently applying a broad-spectrum SPF and reducing smoking meaningfully extends how long results hold. Think of this as an ongoing maintenance treatment rather than a one-time procedure.

What's the Treatment Like — and What Do You Need to Know First?

The procedure involves microinjections delivered across the face in a grid-like pattern — dozens to hundreds of small intradermal deposits, depending on the area being treated. Topical numbing cream applied beforehand makes the experience comfortable for most patients, and a full session typically runs 30 to 45 minutes. Some pinpoint bruising and mild swelling at injection points is expected and usually resolves within 3 to 5 days. If you have an event or travel scheduled soon after, factor that recovery window into your timing.

A few things are essential to disclose before treatment. Because the source material is salmon, patients with fish allergies carry a meaningful risk of hypersensitivity reaction — this must be flagged to your provider before you begin. Anyone on blood thinners, prone to bruising easily, or with a personal or family history of keloid scarring should also mention this upfront. Treatment should be postponed during pregnancy and avoided over any active skin infection or inflammatory flare in the target area.

Common side effects are localized bruising and swelling. Small, palpable nodules at injection sites are an uncommon but documented occurrence. Standard post-procedure guidance applies: skip heavy makeup, steam rooms, vigorous exercise, and alcohol on the day of treatment to support healing.

One final point worth making plainly: PDRN injections are grounded in legitimate biology and an evidence base that, while still growing, is more substantive than most patients realize. But they don't work identically for everyone, and they're not a universal solution. The right starting point is a thorough consultation where your actual skin condition, any relevant allergies or medical history, and your specific goals are evaluated together — with both the realistic benefits and the honest limitations on the table. Going in with a clear-eyed understanding of what this treatment can and cannot deliver is consistently the best predictor of a satisfying outcome.