Polynucleotides are chains of DNA broken down into short fragments. Rejuran's are extracted from salmon sperm DNA, purified to remove the protein that would cause an allergic reaction, and suspended in a gel-like solution. Salmon DNA is used because these fragments are close enough to human DNA to be well tolerated and are cheap to obtain in quantity.
Injected into the upper layers of the skin, the fragments appear to do two things. They hold water, which is a direct hydrating effect. And they act as a mild signal to the skin's repair machinery — nudging fibroblasts, the collagen-making cells, to become more active, and calming inflammation. The result is skin that behaves a little more like younger skin: better hydrated, slightly thicker, slightly more elastic.
It is worth being clear about what this is not. Rejuran does not fill a fold, project a chin, or lift anything. It contains no cross-linked gel and takes up no meaningful space. Nobody will look at you and see that you have had something done — which is either the appeal or the problem, depending on what you wanted.
The related term you will see is PDRN (polydeoxyribonucleotide). PDRN and PN come from the same source; PN chains are longer. PDRN has a longer history in medicine — it has been used for wound healing and joint injections in Europe and Korea for years. The aesthetic use is much newer than the marketing suggests.
Check the regulatory position where you are being treated. In South Korea and much of Asia this is an approved, routine treatment. In the US the injectable is not approved, and a clinic offering it is using product that was not legally imported for that purpose. That is worth knowing before you decide, not afterward.
Mention any fish or seafood allergy explicitly.
Ask how many sessions the plan involves and the total price. A single session will not do much; the standard course is three or four.
Stop non-essential blood thinners a week ahead if your own doctor agrees — fish oil, high-dose vitamin E, ibuprofen. Never stop a prescribed blood thinner on your own.
Do not book within two weeks of an event. The small bumps left by each injection point are visible.
No alcohol the night before — bruising is the main cosmetic nuisance here and alcohol makes it worse.
Arrive with a clean face.
Expect numbing cream for 20 to 30 minutes. This treatment involves dozens of injection points and the cream matters.
Clear the rest of the day if you can. You will leave with a visibly bumpy face for several hours.
Numbing cream goes on for 20 to 30 minutes and is wiped off.
The injector works across the treatment area placing very small amounts at each point — a grid of injections roughly a centimeter apart, dozens of them across a face. Each one raises a small bleb, like a mosquito bite, just under the skin.
You feel a series of quick stings. Numbing cream takes the edge off but this is a treatment of many small pricks rather than a few, and most people find it more irritating than painful.
Some clinics deliver it with a multi-needle injector gun or a mesotherapy device rather than by hand, which is faster but gives less control over depth.
The area is often massaged or gently rolled afterward to help the blebs spread and flatten.
A session usually takes 20 to 30 minutes of injecting.
You will leave with a face covered in small raised bumps and some redness. That is expected and it is the normal look at the end of this treatment.
First few hours. A visible pattern of small raised bumps, redness, and a tight feeling. Ice helps, but the bumps are the product and cold will not remove them.
Day 1. Most bumps have flattened. Bruises begin to show, particularly around the eyes if that area was treated.
Days 2–3. Bumps generally gone. Bruises are usually the only remaining sign, and makeup covers them.
Week 1. Skin often feels smoother and better hydrated. This early change is partly the water the polynucleotide is holding.
Weeks 4–12. The slower change — texture, fine lines, elasticity — building across the course of sessions.
Leave makeup off for the rest of the day if you can, and avoid saunas, steam rooms, hot yoga and strenuous exercise for 24 to 48 hours. Do not use acids or retinoids on the treated skin for a couple of days.
Sun protection matters here, as with any procedure that inflames the skin — a bare treated face in strong sun invites dark marks.
What people report, and what the small trials support, is modest: skin that looks better hydrated, slightly firmer, a little less crepey, with fine lines softened. Photographs before and after a full course usually show a change you can see if you are looking for it and would not notice if you were not.
It builds across the course. Most people say the difference is clear after the third session, not the first, and continues to improve for a month or two after the last.
How long it lasts: commonly six to twelve months before people feel it has faded. Maintenance sessions once or twice a year are the usual pattern, which makes it an ongoing cost rather than a one-off.
Who is disappointed: anyone hoping for the results they saw in social media videos, anyone with volume loss or sagging, and anyone who bought one session. This is a subtle skin-quality treatment sold in an aesthetics market that mostly advertises dramatic ones.
An honest note on the evidence. The published research is real but limited — small groups, short follow-up, much of it conducted in Korea and some of it funded by the manufacturer. There is nothing suggesting it does not work, and nothing on the scale that exists for retinoids, lasers or hyaluronic acid fillers. Treat confident claims about specific percentages of collagen increase as marketing.
Compared with the alternatives: microneedling targets similar problems by a different route and is cheap and available everywhere. PRP is another injected skin-quality treatment with its own mixed evidence. Skinvive, the FDA-approved hyaluronic acid skin booster, hydrates well but does not claim a repair effect. None of these are dramatic. A prescription retinoid used daily for a year probably out-performs all of them for skin texture, and costs a fraction as much.
There is no legitimate at-home injectable version, and this is one of the places where the gap between what is legal and what is being sold online is widest.
Rejuran vials are readily available from overseas resellers, and people do buy them and inject themselves or have a non-medical person do it. Do not. Products bought this way are frequently counterfeit, are not sterile once handled outside a clinic, and put a needle in your face without anyone present who can recognize a blocked vessel. "Hyaluron pens" and needle-free injectors are worse, not better — the FDA has specifically warned against them.
Topical PDRN and polynucleotide products — serums, ampoules, sheet masks, including Rejuran's own cosmetic line — are legal and are sold openly in the US. They are also a different product doing a different thing. A polynucleotide molecule is far too large to cross intact skin, so whatever benefit these give comes from the moisturizing base, not from the DNA. Buy them because you like the texture, not because you expect the injectable result.
Applying an injectable product on top of at-home microneedling is a genuinely bad idea. Home rollers do not create a sterile channel, and pushing an unapproved injectable into an open wound bed is how people get granulomas and infections.
If you want better skin texture at home, the boring answer remains the best one: a prescription retinoid such as tretinoin, daily sunscreen, and a moisturizer with hyaluronic acid and niacinamide. That combination has more evidence behind it than any skin booster on the market.