What is PDRN (Salmon DNA)? | A guide to understanding this trending beauty ingredient through its mechanism, research, and how to choose it.

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In recent years, the term "PDRN" has become a familiar sight on Korean cosmetic shelves and across social media. Often accompanied by marketing copy such as "derived from salmon" or "originated in aesthetic medicine," it is a ingredient that has likely piqued your interest.

However, it is also an ingredient shrouded in questions: "Is it the same as salmon injections?" "Does it regenerate the skin just by applying it?" "Can it be used on hair and the scalp?" In this article, we will explain what PDRN is, what mechanisms researchers are currently studying, and the major differences between aesthetic medical procedures and cosmetic products, in a way that is as accurate and easy to understand as possible for newcomers.

What is PDRN? In short: "DNA fragments extracted from salmon"

PDRN stands for "Polydeoxyribonucleotide." It is a long name, but it becomes easier to visualize when broken down:

• Nucleotide: The smallest component that makes up DNA.
• Deoxyribo: Indicating that this component belongs to "DNA."
• Poly: Meaning "many." It refers to a state where many components are linked together.

In other words, PDRN consists of "DNA fragments" where many DNA components are linked together. The PDRN used in medical and research fields is primarily extracted and purified from the sperm—commonly known as "milt"—of salmonid fish (such as rainbow trout or chum salmon). This is why it is often referred to as "salmon DNA."

Hearing "DNA" might make you worry about "changing your genes," but that is not the case. PDRN is treated as "raw material" broken down into pieces, rather than a "blueprint" that carries genetic information. DNA is commonly found in the fish and meat we consume in our daily diet.

Why is it so popular right now?

PDRN is not actually a new ingredient. Originally, it was researched in Italy and other countries within the medical field to support wound healing. Review papers by researchers have introduced its study in various scenarios, including diabetic foot ulcers, burns, and wounds in areas with poor blood circulation.

Later, treatments involving the injection of PDRN and PN (which I will explain later) into the skin gained popularity in Korean aesthetic medicine. In Japan, these are sometimes known as "salmon injections" or, based on a leading product, "Rejuran." As these treatments became more popular, skincare products containing the same ingredient began to appear one after another, leading to its sudden widespread recognition as an "ingredient originating in aesthetic medicine."

The two mechanisms of PDRN reported in research

Research in the medical field has primarily reported the following two mechanisms for how PDRN works. Please note beforehand that these studies mainly focus on cases where the ingredient is delivered into the body via methods like injection.

Mechanism 1: Sending a signal to cells to "start repair"

On the surface of cells, there are structures called "receptors"—think of them as keyholes—that only accept specific substances. PDRN has been found to work on the "adenosine A2A receptor."

When a signal reaches this keyhole, it is believed to trigger a switch within the cell related to the repair of damaged tissue. Research has reported changes such as the easier formation of new blood vessels and the suppression of inflammation.

Mechanism 2: Becoming "raw material" for cells to create DNA

When cells multiply, they need to create new DNA. Besides synthesizing DNA components from scratch, the body has a recycling-like mechanism called the "salvage pathway," which collects and reuses existing components.

The small components created when PDRN is broken down are believed to be used as materials for this recycling. If the materials are available, cells can efficiently create new DNA.

The most important point: Injections and cosmetics are different

When looking into PDRN, it is not uncommon for aesthetic medicine and cosmetic topics to be conflated. However, these two are completely different in terms of where they are delivered, their purpose, and their regulatory rules.

Another thing to know is the "size" of PDRN. The molecular weight of PDRN used in research is approximately 50 to 1,500 kilodaltons. Compared to the standard size considered difficult to pass through the skin barrier (approx. 500 daltons), this molecule is hundreds or thousands of times larger. Therefore, it is unlikely that it could penetrate deep into the skin just by being applied normally, as injections do.

Does this mean PDRN in cosmetics is meaningless? Not at all. In cosmetics, PDRN is mainly formulated as a "moisturizing ingredient" that holds moisture on the skin surface. The improvements in skin firmness, gloss, and skin texture are naturally attributed to this hydration.

What is the difference between PDRN and PN?

In information about Korean cosmetics and aesthetic medicine, the term "PN (Polynucleotide)" often appears alongside "PDRN." Both are DNA fragments derived from salmon, and they have a relationship akin to relatives in terms of raw materials.

Generally, it is explained that PDRN is DNA strands cut into shorter lengths, while PN consists of longer strands. PN has the characteristic of more easily forming a thick, gel-like texture. In aesthetic medicine, these differences in properties are sometimes used to differentiate their application.

However, naming conventions and processing methods vary by manufacturer, and there is no clear-cut boundary. When choosing cosmetic products, it is more reliable to check the ingredient labels mentioned in the next section or the overall formulation of the product rather than focusing on "PDRN vs. PN."

Labeling as "DNA-Na" on cosmetics

On Japanese cosmetic ingredient labels, the name "PDRN" is almost never used. The sodium salt of DNA obtained from sources like salmon milt is generally listed under the name "DNA-Na." Please check not only the "Contains PDRN" claim on the packaging but also the full ingredient list on the back.

PDRN and the scalp/hair: What we know now

Since KEMA is a hair care brand, let's talk about the scalp and hair from here. You might be thinking, "If it's good for the face, isn't it good for the scalp and hair?"

Regarding the scalp: Research on "injections" has just begun

Internationally, research investigating the effects of PDRN and PN on hair loss (androgenetic alopecia) via injections into the scalp has begun to appear. For example, a study in which 28 men with androgenetic alopecia were injected with PN four times at four-week intervals reported improvements in hair thickness and density, with no severe side effects.

However, this is a small-scale study and did not include a control group (people who did not receive injections). Furthermore, it is research based on medical injections, which does not mean that the same result occurs with shampoos or tonics applied to the scalp. If you are concerned about hair loss or thinning, it is best to consult a specialist, such as a dermatologist, instead of making self-judgments.

Regarding hair: The hair itself does not "regenerate"

Another thing to understand is the nature of hair. Hair that has grown out from the scalp is no longer living tissue. Therefore, the hair itself cannot repair or regenerate on its own. The mechanisms by which PDRN "sends signals to cells" or "becomes DNA material" rely on the presence of living cells, so they do not apply to the hair shaft itself.

When DNA-Na is included in hair care products, its role is primarily "moisturization." Please consider it an ingredient designed to hold moisture on the hair surface, suppress dryness, and provide a smooth, soft texture.

5 tips for choosing PDRN-containing products

Based on the information above, I have summarized points to keep in mind when choosing PDRN-containing skincare or hair care products.

Caring for the scalp as an "extension of facial skin"

Behind the intense focus on PDRN is a common desire to "keep the skin healthy." And that desire should be directed not only to the face but also to the scalp.

The scalp is "skin" that is continuous with the face. Furthermore, it is a location covered by hair that makes it harder to notice the effects of UV rays and dryness, and it is prone to high sebum secretion. Before searching for trendy ingredients, the shortcut to a healthy scalp environment is to establish the basics: "wash without stripping away necessary sebum," "provide moisture after washing," and "dry immediately without leaving it damp."

At KEMA, we offer scalp care products designed to treat the scalp as skin. Neither is a product marketed solely on PDRN, but both are highly recommended as daily care to keep the scalp hydrated and in a healthy state.

KEMA Scalp Shampoo

Cleanses away excess sebum and dirt while maintaining necessary moisture. A scalp care shampoo that addresses scalp concerns such as stickiness, odor, dandruff, and itching.

¥9,020 (tax included)

KEMA Scalp Tonic

A scalp tonic applied directly to the scalp after shampooing to keep the environment healthy, which is prone to disruption from dryness or stickiness. Recommended even for scalp care beginners.

¥9,020 (tax included)

Frequently Asked Questions

Are "salmon injections" and PDRN-containing cosmetics the same thing?

Although their raw material origins are similar, please consider them completely different. Injections are a medical act performed by a physician to deliver the substance deep into the skin, while cosmetics are intended to provide moisture to the skin surface. You cannot expect the same effects from cosmetics as you would from injections.

Does skin regenerate when applying PDRN-containing cosmetics?

Cosmetic products cannot claim "regeneration," and because PDRN molecules are large, it is considered unlikely that they would penetrate deep into the skin just by being applied. PDRN (DNA-Na) in cosmetics should be utilized as a moisturizing ingredient.

Is PDRN effective for hair loss or thinning?

While there is research investigating the effects of scalp injections on hair loss, it is still small-scale, and it cannot be said that the same effect occurs with topical hair care products. If you are concerned about hair loss or thinning, we recommend consulting a specialist, such as a dermatologist.

Can I use it if I have a fish allergy?

Since PDRN is derived from sources like salmon milt, please consult a physician before use if you have an allergy to seafood. If you feel any abnormalities such as redness or itching during use, stop using the product immediately.

Should I choose PDRN or PN for cosmetics?

In cosmetics, naming and processing methods vary by manufacturer, and you cannot determine superiority based on the name alone. It is recommended to choose based on the ingredient list, the overall formulation, and the actual usage experience.

Summary: When choosing trendy ingredients, understand the "mechanism" and "delivery location"

PDRN is a fragment of DNA extracted from salmon milt. In the medical field, it is an ingredient whose mechanisms—sending repair signals to cells and acting as raw material for DNA—have been studied. However, most of this research involves delivering the substance inside the body via injection. When applied to the skin or scalp as a cosmetic, its primary role is as a "moisturizing ingredient to provide hydration."

KEMA values the concept of "designing beauty from the structure." Rather than jumping on trendy keywords, we believe in choosing products after understanding the "mechanism" of how an ingredient reaches and acts on your skin. We believe this leads to care that is truly meaningful for your skin and hair.