How Rejuran and Polynucleotide Skin Boosters Actually Work: The Mechanism Explained

Polynucleotide skin boosters, marketed in Korea under names such as Rejuran, work by delivering fragmented DNA chains derived from salmon milt into the dermis, where they are thought to act as a biological scaffold and signalling substrate rather than as a volumising filler. That distinction matters. A hyaluronic acid filler occupies space; a polynucleotide injection is intended to influence how the skin behaves over the following weeks. Most consumer articles describe the effect as "skin regeneration" without explaining the proposed mechanism or its evidentiary limits. This guide separates what the biology plausibly supports from what remains marketing language.

What Polynucleotides Actually Are

Polynucleotides are chains of nucleotides, the same building blocks that make up DNA, purified and fragmented to a controlled molecular weight. In aesthetic products the source is typically salmon or trout gonadal tissue, chosen because the DNA is highly purified and its sequence homology with human DNA is high enough to be well tolerated while carrying no functional genetic information. The material is processed to remove proteins, which is the step intended to minimise immunogenic risk. What is injected is therefore a sterile gel of DNA fragments in solution, not living cells and not a growth-factor concentrate. Products differ in fragment length, concentration and viscosity, and these differences plausibly affect handling and clinical behaviour.

The Proposed Mechanism, Step by Step

Three mechanisms are generally proposed. First, a physical hydrating scaffold: polynucleotide gel binds water in the dermis, temporarily improving hydration and viscoelasticity. Second, a salvage-pathway effect: as the fragments are broken down, the released nucleotides may be reused by surrounding cells, potentially supporting fibroblast metabolism at a time of increased demand. Third, a signalling effect: laboratory work has suggested polynucleotides can influence adenosine A2A receptor pathways, which are associated with modulation of inflammation and fibroblast activity. These mechanisms are supported by preclinical and small clinical studies, and the strength of evidence varies considerably between them. They should be described as plausible rather than established.

What the Evidence Supports and Where It Thins

Published studies, largely small and often single-centre, have reported improvements in skin hydration, elasticity and fine surface texture following courses of polynucleotide injection, and reasonable short-term tolerability. Where the evidence thins is in long-term durability, in head-to-head comparison against other injectable boosters, and in standardised objective outcome measurement. Much of the available literature indexed on PubMed involves modest sample sizes and relatively short follow-up. A reasonable reading is that polynucleotide boosters can produce measurable short-term improvement in skin quality parameters in suitable patients, while claims of structural rejuvenation or collagen remodelling equivalent to energy-based devices remain insufficiently supported.

What It Is Not: Filler, Botulinum Toxin or Laser

Polynucleotide injection does not create volume in the way a cross-linked hyaluronic acid filler does, so it will not lift a nasolabial fold or project a chin. It does not relax muscle, so it will not soften dynamic expression lines. It does not deliver controlled thermal injury, so it will not resurface acne scarring or fragment pigment the way a laser can. Clinics frequently combine polynucleotide boosters with these modalities precisely because the targets differ. If a clinic proposes a booster course as a substitute for a laser or filler indication, ask them to explain the mechanistic rationale.

The Competitor Gap: Course Design Is Rarely Explained

Most English-language articles describe what the product is and then jump to price. The variable that actually determines patient experience is course design: how many sessions, at what interval, at what injection depth and density, and with what maintenance schedule. Typical protocols involve an initial series of three to four sessions spaced two to four weeks apart, followed by maintenance at intervals of several months. Injection technique also varies between multiple microdroplet placement and linear threading, which changes both discomfort and bruising likelihood. A clinic that cannot articulate its protocol and rationale is a weaker choice than one that can, regardless of headline price.

Side Effects, Contraindications and Practical Cautions

Commonly reported effects are injection-site papules that typically settle within one to several days, bruising, transient swelling and tenderness. Less common issues include nodule formation and infection, which requires prompt medical review. Because the source material is fish-derived, a documented fish allergy is generally treated as a contraindication. Pregnancy, breastfeeding, active skin infection at the treatment site and autoimmune conditions under active treatment are commonly listed as reasons to defer or seek specialist advice. Treatment should be performed by a licensed physician using product obtained through legitimate distribution channels; product provenance is a genuine safety issue in cross-border aesthetic tourism.

Questions Worth Asking Before Booking in Korea

Ask which specific product and concentration will be used and whether it is domestically approved. Ask how many sessions the clinic considers a complete course for your skin, and what the expected maintenance interval is. Ask what objective measure, if any, they use to evaluate response. Ask what happens if you see no change after the full course. For international patients, also confirm the interval feasibility: a three-session course at two-week intervals requires either an extended stay or repeat travel, and compressing intervals to fit a trip is not automatically equivalent.

Frequently Asked Questions

How soon are results visible?

Patients commonly report improved hydration and a smoother surface within one to two weeks of the first session, with more noticeable change after the second or third. Because the proposed mechanism involves cellular activity rather than volume placement, immediate post-injection appearance is not a reliable indicator of the eventual result.

How long do results last?

Reported durability after a full initial course commonly falls in the range of several months, after which maintenance sessions are typically recommended. Duration varies with age, baseline skin condition, sun exposure and lifestyle, and published long-term follow-up data remain limited.

Is it painful?

Discomfort is generally described as moderate, and topical anaesthetic is standard. Multiple microdroplet placement over an area such as the under-eye or full face involves many injection points, so tolerance varies. Bruising is common in thin-skinned areas.

Can it be combined with laser or toxin on the same day?

Combination protocols exist, but sequencing and spacing differ between clinics, and combining several procedures in one visit can make it harder to attribute any adverse reaction. Discuss the sequencing rationale rather than accepting a bundled package by default.

Is it suitable for acne scarring?

Polynucleotide boosters may improve overall skin texture, but they are not a primary treatment for atrophic acne scars, which are usually addressed with subcision, TCA CROSS or fractional resurfacing. A booster may be used adjunctively rather than as a substitute.

Related Reading

How Pico Laser Actually Works: The Mechanism Explained | Exosome Skin Therapy in Korea (2026): What the Evidence Does and Does Not Show | How to Vet a Korean Clinic: A 15-Point Checklist

Sources

Background and safety context drawn from: Korea Health Industry Development Institute (KHIDI), Korean Medical Association, and peer-reviewed literature indexed on PubMed. This article is general information, not medical advice.

Next Step

If you are considering a polynucleotide course in Korea, request the product name, session count, interval schedule and total written cost before travelling, and confirm that the schedule is achievable within your stay.