What Is PDRN in Hair Care?
The Science Behind the ULULIS Black Serum
If you've been researching Japanese hair oils recently, you may have seen the acronym PDRN appearing on packaging and in ingredient lists. It's a legitimate ingredient with a serious research history in medicine — but in hair care, it's still almost entirely absent from Western-facing products. The ULULIS Premium Black Serum Hair Oil is among the first mass-market J-beauty products to formulate with it. This is what you need to know.
What PDRN Actually Is
PDRN stands for Polydeoxyribonucleotide. It is a purified, fragmented form of DNA derived from salmon sperm or trout testes. In cosmetic ingredient lists, it often appears as DNA-Na (sodium DNA) or simply listed as PDRN. It is a precision moisture-binding and cellular-support active with a decades-long track record in regenerative medicine before entering cosmetics.
The molecular structure of PDRN allows it to bind to adenosine A2A receptors on cells — receptors that regulate tissue repair, moisture retention, and inflammation response. In aesthetic medicine, this makes it useful for wound healing, skin rejuvenation, and joint treatment. In hair care, the same mechanism supports cellular-level moisture retention in the hair cortex and helps stimulate the conditions for structural repair.
How PDRN Went from Medicine to Hair Care
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11980s–1990s — Medical OriginsPDRN first studied in Italy for wound healing and tissue regeneration. Used in ophthalmology and dermatology for its ability to accelerate cellular repair.
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22000s–2010s — Korean Aesthetic MedicinePDRN becomes widely used in Korean skin boosters and injectable skin treatments ("Rejuran" injections). Builds a strong clinical evidence base for skin moisture restoration and anti-ageing.
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32015–2020 — Topical SkincareJapanese and Korean cosmetic formulators begin incorporating topical-grade PDRN into serums and creams. The ingredient transitions from medical devices to cosmetic products.
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42025–2026 — Hair Care EntryULULIS Premium Black Serum Hair Oil launches in Japan featuring PDRN (listed as DNA-Na) combined with Tosurea and exosomes — bringing medical-grade repair technology to accessible J-beauty hair care for the first time at this price point.
How It Works on Hair: Surface vs. Structural Repair
Most of what the hair care industry calls "repair" is actually surface coating. Understanding the difference is important because it determines what a product can realistically achieve.
Surface Repair (Most Oils)
- Silicone fills the gap between cuticle scales
- Hair looks smooth and shiny immediately
- Washes off with every shampoo
- No change to internal structure
- Results plateau from day one
- Heavy use can cause build-up
Structural Repair (PDRN + Tosurea)
- PDRN restores moisture environment inside the cortex
- Tosurea bonds to broken disulphide bonds in the shaft
- Results accumulate over time
- Hair behaves differently — not just looks different
- Less dependent on continuous product use for effect
- Addresses the cause of frizz, not the symptom
The Full Repair Team in the Black Serum
PDRN doesn't work alone. The Black Serum formula combines several actives, each addressing a different dimension of damage. Here's the complete picture:
| Active | Works At | Speed of Effect | Cumulative? |
|---|---|---|---|
| PDRN (DNA-Na) | Inside the cortex | 2–3 weeks for full effect | Yes — builds over time |
| Tosurea® | Broken bonds in cortex | 3–7 days noticeable | Yes — more bonds repaired each use |
| Hydrolysed Keratin | Cuticle surface + gaps | First use | Partial — washes off but replenished |
| Soluble Collagen Water | Hair shaft exterior | First use | Partial |
| Exosome Complex | Barrier layer | 1–2 weeks | Yes |
| Black Diamond Truffle | Surface conditioning | First use | No — surface effect each application |
Who Benefits Most from PDRN in Hair Care
PDRN is not a mass-appeal "everyone benefits" ingredient. Its value is concentrated in specific hair situations where internal structure has been compromised. Understanding when PDRN makes a meaningful difference:
| Hair Situation | PDRN Relevance | Expected Benefit |
|---|---|---|
| Bleached / lightened hair | Very high | Bleach destroys cortex moisture structure — PDRN directly restores this |
| Chemically permed / relaxed | Very high | Chemical treatment breaks disulphide bonds — PDRN + Tosurea target this specifically |
| Heat-damaged (regular blowdry, iron) | High | Heat progressively degrades moisture retention inside the cortex |
| Age-related texture change | High | Cortex moisture capacity declines with age; PDRN helps restore it |
| Colour-treated (tint, semi-perm) | Moderate–High | Less aggressive than bleach, but repeated colour processing accumulates damage |
| Healthy, undamaged hair | Low | PDRN works on compromised structure — less to repair = less visible effect |
The Product: ULULIS Premium Black Serum Hair Oil
The ULULIS Premium Water Conc. Black Serum Hair Oil is currently the only accessible, mass-market hair oil in English-speaking markets that combines PDRN, Tosurea, and exosomes in a single leave-in formula. It launched in Japan in early 2026 and is sourced directly from Japanese domestic retail — the same formula sold in Matsumotokiyoshi and Japanese pharmacies today.
ULULIS Premium Water Conc. Black Serum Hair Oil 100ml
Japan-domestic formula. PDRN + Tosurea + exosomes. 95%+ moisture and repair actives. Ships direct from Tokyo.
Shop on TokyoShelf →For a full review of the product including texture, results timeline, and usage instructions, see the ULULIS Black Serum Hair Oil Review. To compare the Black Serum against other ULULIS lines, see the ULULIS Line Guide.
Also available in the Hair Oils & Serums collection: &honey Deep Moist Hair Oil, Orbis Essence In Hair Milk, Fino Premium Touch Hair Oil, and more — all sourced directly from Japan.