Guide · Polynucleotides (PN)

Polynucleotides (PN) how they differ from PDRN, and what the evidence shows

Polynucleotides are purified salmon DNA fragments injected to improve skin quality, especially thin, crepey skin under the eyes. Here is how PN differs from PDRN, what the studies actually found, and how injected PN compares with a needle-free PDRN facial.

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Quick answer

Polynucleotides (PN) are purified fragments of salmon DNA, with the proteins removed, injected in tiny amounts into the dermis to improve skin quality: fine lines, crepey texture, hydration and elasticity. They are not fillers and do not lift or add volume.
PN and PDRN come from the same source and the terms are often used interchangeably. A 2025 review proposed reserving PDRN for shorter chains under 1,500 kDa and PN for longer chains of 1,500 kDa or more; injectable PN boosters are usually the longer-chain type, while c-PDRN is used in facials and skincare.
The evidence is promising but limited. A 2025 systematic review found nine low-to-moderate quality studies with 219 patients, and a 27-person randomised split-face trial found PN performed similarly to a non-cross-linked HA booster around the eyes, with better results for roughness and pores.
In Singapore, injected PN is a medical procedure. At IN Eternity Clinic, Dr Sin Yong performs PN boosters, priced at consultation; at SkinRev Lab, CityLink Mall, the needle-free Rejuran PDRN Facial is S$128 to S$348 before GST, a gentler topical option.

The basics

What polynucleotides are

Polynucleotides are chains of DNA building blocks. The versions used in medicine and aesthetics are purified from the sperm DNA of salmon trout or chum salmon, then processed to remove the proteins that could trigger immune reactions. They were first used as a tissue-repair medicine, including for slow-healing wounds, before moving into aesthetics.

Laboratory and clinical work suggests they act mainly through adenosine A2A receptors, which are involved in tissue repair and in calming inflammation, and that they supply building blocks cells can reuse, known as the salvage pathway. Injected PN also binds water and is thought to form a scaffold-like gel in the dermis that supports fibroblasts, the cells that make collagen.

In plain terms, PN is a skin-quality treatment. It is used for thin, tired or crepey skin, fine lines and texture. It does not fill hollows, lift sagging skin or remove pigment.

Salmon DNA facials and PDRN explained →Injectable skin boosters: HA, PN and PDLLA →

PN vs PDRN

PN vs PDRN: same source, different chain length

PDRN (polydeoxyribonucleotide) and PN (polynucleotide) are both DNA fragments from salmon, and for years the two names have been used for products of very different chain lengths. A 2025 review in Biomolecules proposed a simple cut-off: PDRN for small and medium chains under 1,500 kDa, PN for longer chains of 1,500 kDa or more. Several of its authors worked for companies in this field, and the cut-off is a proposal rather than a regulatory rule.

The practical point is that a label saying PDRN, PN or salmon DNA does not tell you the concentration, chain length or whether it is meant for injection or for the skin surface. Ask what the product is and how it is given.

Term	What it usually means	Where you meet it
PDRN	Shorter-chain DNA fragments, roughly 50 to 1,500 kDa	Wound-healing medicines, some injectables, skincare
PN (polynucleotide)	Longer-chain DNA polymers, 1,500 kDa or more under the proposed definition	Injectable PN boosters given by a doctor
c-PDRN	Cosmetic-grade PDRN for use on the skin	Facials and skincare, such as the Rejuran PDRN Facial
Salmon DNA	A popular name for any of the above	Advertising for both injections and facials

PDRN and Rejuran facials explained →Rejuran in Singapore: injected vs needle-free →

Under the eyes

PN for under-eye skin: what the studies found

The under-eye area is one of the most common reasons people ask about PN, because the skin there is thin and creases easily. In a randomised, double-blind split-face trial of 27 people, each had three sessions two weeks apart, with PN on one side and a non-cross-linked HA booster on the other. Overall improvement scores were similar for both, while the PN side showed greater gains in roughness and pore volume and higher improvement rates for elasticity and hydration. No serious side effects were reported.

A 2026 observational study of 42 patients given intradermal PN under the eyes found that their own ratings of the lower eyelids and crow's feet improved at one, three and six months, most at three months after two sessions, with minimal side effects. It had no comparison group, so it shows a trend rather than proof.

Under-eye concerns have different causes. PN suits fine lines and crepey, thin skin. A hollow tear trough needs volume, which PN does not provide; dark circles from pigment or visible vessels need other approaches. A doctor should work out which you have first.

Under-eye lines →Dark eye circles →Tear trough filler →

Skin quality

Other uses: fine lines, texture and sensitive skin

A survey of 235 Korean board-certified dermatologists found that 88% used PN injections. The most common uses were fine lines on the cheeks, fine lines under and around the eyes, uneven texture, dry skin and forehead lines. Most injected into the dermis with a very fine needle, usually as three sessions four weeks apart, and 79% combined PN with energy treatments such as radiofrequency or focused ultrasound.

PN is also used for thin or barrier-compromised skin and as part of acne-scar plans, although the published studies for scars are small. Deep or pitted scars usually need resurfacing or a combined scar plan, with PN as a supporting step at most.

Fine lines and wrinkles →Sensitised skin →Acne scars →

Evidence

How strong is the evidence?

A 2025 systematic review of polynucleotides in aesthetic medicine found nine studies, all of low or moderate quality, covering 219 patients. Injection areas and techniques varied. Results for wrinkles, texture and elasticity were promising, side effects were generally mild and short-lived, and the authors concluded that rigorous, high-quality studies are still needed. Two of the four authors declared commercial links to PN companies.

That is a fair summary of where PN stands: widely used, generally well tolerated, with encouraging but small studies. It is reasonable to try for skin quality with realistic expectations, but it is not a substitute for treatments aimed at sagging, volume loss or pigment. Results vary between people.

Comparison

Injected PN vs HA booster vs needle-free PDRN

	Injected PN booster	Injected HA booster	Needle-free PDRN facial
Main action	Repair signalling and a water-binding scaffold	Holds water in the dermis	Cosmetic-grade PDRN on the skin, helped past the outer barrier
Who performs it	A doctor	A doctor	An aesthetic therapist
Typical course	Often three sessions a few weeks apart	A short course, then maintenance	A course of facials, then maintenance
Afterwards	Small bumps and redness for hours to a day or two; bruising possible	Similar	Usually no recovery time
Evidence	Promising, small studies	Promising, small studies	Limited; little published on facial devices
In our network	IN Eternity Clinic, priced at consultation	IN Eternity Clinic, priced at consultation	SkinRev Lab, S$128 to S$348 before GST

HA vs PN boosters →Needle-free vs injectable skin boosters →

At IN Eternity Clinic

Injectable PN with Dr Sin Yong

Injectable PN boosters are performed by Dr Sin Yong (MBBS Singapore, MRCS Edinburgh, MSc Practical Dermatology Cardiff), SkinRev Lab's Medical Adviser, at IN Eternity Clinic, 9 Scotts Road, #12-01 Pacific Plaza, beside Orchard MRT. He assesses the skin first and may suggest PN, an HA or PDLLA booster, a combination, or a different treatment if PN will not do what you want.

Numbing cream is usually applied for 20 to 30 minutes. Expect a grid of small bumps and redness that settles within hours to a day or two, a little longer on thin under-eye skin, and possible bruising. Avoid make-up for the rest of the day and saunas or hard exercise for a day or two. The clinic prices the plan at consultation: WhatsApp +65 8815 3008.

Injectable skin boosters at IN Eternity Clinic →Dr Sin Yong, Medical Adviser →

Needle-free

The needle-free route: Rejuran PDRN Facial at SkinRev Lab

SkinRev Lab, a non-invasive aesthetic centre at #B1-28 CityLink Mall by City Hall MRT, does not inject. Its Rejuran PDRN Facial applies cosmetic-grade c-PDRN with Meso Touch transdermal technology, across nine tiers from S$128 to S$348 before GST. The Needleless SkinBooster, S$288 per region before GST, delivers hydration, tone or skin-quality boosters without needles.

Be clear about the difference. Intact skin lets very little through above about 500 daltons, and DNA fragments are far larger, so a facial does not place PDRN where an injection does. We describe it as a gentle, course-based improvement in hydration, calmness and texture, suited to people who want no needles or maintenance between other treatments.

Rejuran PDRN Facial →Salmon DNA facial in Singapore →Needleless SkinBooster →

Safety

Safety, and who should wait

PN is derived from fish DNA: tell the doctor about any fish or salmon allergy.
Not advised during pregnancy or breastfeeding, or over infection, cold sores, eczema flares or inflamed acne.
Discuss autoimmune disease, a keloid tendency, bleeding problems or blood-thinning medicines first.
Only a doctor should inject PN. Do not buy booster products online to self-inject.
Even shallow injections can rarely enter a blood vessel, so seek help quickly for pain, skin colour change or vision problems after treatment.
Tell each provider about recent injections, lasers or peels, so treatments are spaced sensibly.

Skin booster prices in Singapore →Regenerative facials in Singapore →

Sources

References & sources

Common questions

Your questions,
answered

What are polynucleotides used for?

Mainly for skin quality: fine lines, crepey or thin skin, texture, hydration and elasticity, especially under the eyes and on the cheeks. They are also used in sensitive skin and as part of acne-scar plans. They do not fill hollows or lift sagging skin.

What is the difference between PN and PDRN?

Both are salmon DNA fragments. A 2025 proposal reserves PDRN for shorter chains under 1,500 kDa and PN for longer chains of 1,500 kDa or more. In practice, injectable PN boosters are usually longer-chain, while c-PDRN is used in facials and skincare. Ask what a product actually contains.

Are polynucleotides good for under-eye wrinkles?

They can help fine lines and crepey skin under the eyes. A randomised split-face trial found PN performed similarly to an HA booster overall, with better results for roughness. They will not fill a hollow tear trough, and dark circles from pigment or vessels need other treatment.

How many PN sessions do I need?

A survey of Korean dermatologists found three sessions four weeks apart was most often recommended, followed by maintenance. The doctor sets the plan after assessing your skin.

How long does PN downtime last?

Small bumps and redness usually settle within hours to a day or two, slightly longer on under-eye skin. Bruising is possible and can take several days to fade. Most people return to work the next day.

Is polynucleotide injection safe?

In published studies, side effects were mostly mild and short-lived. Rare risks include infection and an injection entering a blood vessel, so it should only be done by a doctor. Tell the doctor about fish allergy, pregnancy or skin infection.

Is a salmon DNA facial the same as a PN injection?

No. A facial applies cosmetic-grade PDRN to the skin without needles and acts mainly near the surface, so it is gentler. An injection places professional-grade PN into the dermis. Both have a place, but they are not interchangeable.

How much do polynucleotide injections cost in Singapore?

It depends on the product, the areas and the number of sessions. At IN Eternity Clinic, PN boosters are priced at consultation by the clinic. At SkinRev Lab, the needle-free Rejuran PDRN Facial is S$128 to S$348 before GST.