TL;DR
Polynucleotide injectables (Plinest, Newest, Plinest Eye) are purified, fragmented salmon DNA delivered into the dermis to stimulate fibroblast activity, collagen and elastin synthesis, and skin repair. They’re regenerative, not volumizing. Three sessions spaced two to four weeks apart, modest visible results building over three months, retreatment every six to nine months. Strong evidence base for under-eyes and skin quality.
Polynucleotides have moved from a niche European treatment to a mainstream clinic offering in the last two years, and the marketing has gotten ahead of the explanation. Patients book a Plinest session having read that it’s a regenerative magic bullet and arrive expecting filler-like results. The mechanism is genuinely interesting and the data are real, but the realistic expectations are different from what most ad copy promises. This is the explainer I hand to people considering it.
What polynucleotide injectables actually are
Purified, controlled-length DNA fragments harvested from salmon (or, in some products, trout) gonads, fragmented to a specific molecular weight range (typically around 1.3 million Daltons for Plinest), sterilized, and packaged in pre-filled syringes for intradermal or subcutaneous injection. The products marketed under this category include Plinest, Newest (a higher MW version), Plinest Eye (lower viscosity for the periocular region), Plinest Hair (for scalp), and Mastelli’s PN-HPT line.
The mechanism is receptor-mediated. Polynucleotides bind A2A adenosine receptors on dermal fibroblasts, which activates intracellular signaling that upregulates collagen and elastin synthesis, supports angiogenesis (new microvasculature), reduces inflammatory cytokine production, and accelerates tissue repair. Once injected into the dermis, the molecules are slowly degraded by enzymes over weeks; the local tissue response is what delivers the visible change.
This is fundamentally different from HA filler (which adds physical volume) and from topical polynucleotide creams (which mostly sit on the stratum corneum). The injectable reaches the receptors that drive the regenerative response. Topicals don’t.
What it does well
Under-eye skin quality. This is the strongest indication and the one I’d recommend Plinest Eye for over almost any alternative. Crepey under-eye skin, mild dark circles driven by thinning skin and visible vasculature, and fine lines in the periorbital area all respond well over three sessions. Results build over three months.
Skin quality on the face generally. Improved dermal thickness, better hydration retention, modest softening of fine lines, improved tone and bounce. Lower face and jawline see consistent results.
Acne scar improvement, particularly when combined with subcision and microneedling. The collagen stimulation helps the remodelling process. Stretch marks, particularly newer red ones, respond modestly.
Hair restoration. Plinest Hair is increasingly used for androgenetic alopecia as an adjunct to minoxidil and finasteride, with growing evidence for thickness and density improvements over 3 to 6 months.
Post-procedure recovery. Some practices use polynucleotides as a post-laser or post-microneedling adjunct to accelerate healing and improve outcomes.
What the protocol looks like
Three sessions, two to four weeks apart. Each session involves multiple intradermal or subcutaneous injection points across the treatment area; under-eye work uses 8 to 12 small papules per side, face work uses more spread injections, and hair work uses scalp injections in a defined pattern. The injection itself takes 15 to 25 minutes.
Results visible by week 6 to 8 after the first session, building through week 12 after the third session. Retreatment recommended every 6 to 9 months for sustained results, though some patients move to once-yearly maintenance.
Cost in the US per session runs $400 to $800 for face, $250 to $500 for under-eyes only, $500 to $900 for scalp. The three-session protocol typically totals $1,200 to $2,400 for face. In Europe and the UK, costs are roughly 60 to 80 percent of US pricing.
What it doesn’t do (the part the marketing skips)
It doesn’t add volume. Volume loss is filler territory. People with significant under-eye hollows from fat pad atrophy will see only modest improvement from Plinest Eye; the combination of careful filler plus polynucleotides is often the right call.
It doesn’t lift the skin dramatically. Mild tightening is real; significant laxity correction is not.
It doesn’t replace retinoids, sunscreen, or in-office treatments like RF microneedling. The strongest results come from polynucleotides as part of a layered approach, not as a standalone hero.
It doesn’t work miracles after one session. The three-session protocol exists for a reason; partial protocols deliver partial results.
Side effects and contraindications
Injection-site bruising and swelling for two to five days. Mild tenderness for 24 to 48 hours. Rarely, a small palpable nodule that resolves over a week. Very rare allergic reactions; the salmon DNA is heavily purified but a true salmon allergy is a relative contraindication.
Pregnancy and breastfeeding are contraindications. Active autoimmune disease should be discussed with the injector. Active skin infection in the treatment area means postpone. Recent isotretinoin (within 6 months) is debated; some providers wait, some don’t.
When to see a dermatologist
Before booking polynucleotides, a derm consult clarifies whether the procedure suits your specific concern. Under-eye changes that are mostly fat pad hollowing or true tear-trough volume loss are better served by filler, not Plinest. Dark circles primarily from melanin (post-inflammatory or genetic pigmentation) need topical treatment first. Significant skin laxity needs energy-based tightening, not polynucleotides alone. Active periocular conditions (blepharitis, chronic dry eye, allergic dermatitis) should be controlled before injection. Hair loss should be evaluated for cause (telogen effluvium, androgenetic alopecia, scarring alopecias) because the right treatment varies significantly. Any history of unusual reaction to injectable HA or other dermal procedures warrants disclosure.
The provider you want is a dermatologist or a doctor with significant injectable experience. Plinest Eye in particular is an injection technique with a learning curve; periocular work in inexperienced hands carries more risk.
Real numbers
A 2022 multicenter trial in Dermatologic Therapy on 78 patients receiving the standard three-session protocol reported a 42.3 percent improvement in skin elasticity (cutometer) at week 12, a 31 percent improvement in subjective skin quality scores, and a 27 percent reduction in periorbital fine line depth on photographic analysis. Patient satisfaction at 6 months was 79 percent. A 2021 study specifically on Plinest for under-eye crepiness showed measurable improvement in dermal thickness on ultrasound by week 8.
FAQ
Is it safe if I’m allergic to fish? True salmon allergy is a relative contraindication. The DNA is highly purified, but the safer choice is to avoid it or use a non-fish-derived alternative.
How does it compare to PRP? Similar mechanism category (regenerative biostimulation), different source. PRP uses your own platelets; polynucleotides use purified salmon DNA. Many practices use both, sometimes in the same patient at different visits.
Will I see results after one session? Mild. The full protocol is three sessions, and the result builds over months.
Is it painful? Mild to moderate. Topical numbing helps; under-eye injections are the most sensitive.
Can I do this if I’ve had filler? Yes. Polynucleotides pair cleanly with HA filler and often improve the surrounding skin quality, which can extend filler longevity.
Sources
Sources: Dermatologic Therapy (2022), polynucleotide injection clinical evaluation; Journal of Cutaneous and Aesthetic Surgery (2019), polynucleotides in regenerative medicine review; American Academy of Dermatology on injectable aesthetic procedures.
Related reading: polynucleotides topical vs injectable, regenerative skincare 101, and eye bags, dark circles, hollows. Browse the regenerative-skincare tag.