Patient Guide: Polynucleotides

Polynucleotides are injectable purified DNA fragments that stimulate cellular repair, fibroblast proliferation and tissue regeneration from within the skin. At The London Road Clinic, we use Croma Polyphil, manufactured by Croma Pharma, for both facial skin quality and hair restoration. From £250 per session.

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What polynucleotides are

Polynucleotides (PNs) are long chains of nucleotides, the building blocks of DNA, purified from salmon trout and processed to remove proteins that could cause immune reactions. The resulting injectable is a highly purified biological molecule with a specific and well-researched mechanism of action in human tissue.

They are sometimes referred to as PDRN (polydeoxyribonucleotide), a closely related term. At clinical level the distinction is one of molecular chain length, but for patients the practical meaning is the same: a purified, bio-compatible injectable that acts on the body’s own cellular repair systems.

Polynucleotides are not the same as hyaluronic acid. They are not a skin booster in the conventional sense, and they are not a dermal filler. They do not add volume. Understanding what they are, and what they are not, is the most important starting point for any patient considering them.

The product we use at The London Road Clinic is Croma Polyphil, manufactured by Croma Pharma, an Austrian pharmaceutical company with a long track record in injectable medical devices. Choosing the specific product matters. The polynucleotide market has expanded rapidly and includes products with significantly different manufacturing standards and evidence bases. Croma Polyphil sits at the top of the published evidence tier.

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How polynucleotides work

Polynucleotides act primarily through two mechanisms, and the distinction between them is worth understanding.

First: adenosine receptor agonism. Polynucleotides bind to A2A adenosine receptors on the surface of cells. This has a direct anti-inflammatory effect, reducing local inflammation in the tissue and creating a more favourable environment for cellular repair. This is why polynucleotides are particularly useful in skin that has suffered cumulative damage, sun exposure, inflammation associated with rosacea, or the chronic low-level oxidative stress of ageing.

Second: fibroblast stimulation and proliferation. Polynucleotides promote the proliferation and metabolic activity of fibroblasts, the cells responsible for producing collagen, elastin and hyaluronic acid. This is the mechanism shared with other regenerative injectables, including Profhilo. The difference is that polynucleotides drive cellular repair and proliferation directly, rather than acting via the extracellular matrix as hyaluronic acid does. The analogy I find useful with patients: Profhilo improves the environment the cells work in; polynucleotides activate the cells themselves.

The result of both mechanisms combined is genuine tissue regeneration: improved skin density and thickness, better hydration, reduction in fine lines associated with skin quality decline, and in the scalp, stimulation of hair follicle activity and improved microcirculation in the dermal papilla.

Understanding collagen, elastin and hyaluronic acid provides useful context for how these mechanisms translate into visible skin changes.

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What polynucleotides can address

Facial skin quality

Polynucleotides are most often considered for skin where quality has declined beyond what a hydration-focused treatment alone can address. Specifically:

• Thin, crepey skin with reduced density, particularly in the lower face, jaw line and neck.
• Skin with a history of significant sun damage, where the inflammatory repair process has not been fully resolved.
• Fine lines associated with reduced skin thickness rather than muscle activity.
• Skin that has not responded as fully as expected to other regenerative treatments.
• The under-eye area: polynucleotides have a well-established evidence base for tear trough and periorbital skin quality, where the tissue is thin and where anti-inflammatory action is particularly beneficial.

Hair restoration

Croma Polyphil is used at The London Road Clinic for scalp treatment in patients experiencing hair thinning or early hair loss. Injected into the scalp, polynucleotides improve microcirculation in the dermal papilla (the structure that supplies the hair follicle with nutrients), reduce scalp inflammation, and promote follicle activity. The full account of hair restoration options, including when polynucleotides are appropriate and when other approaches are more suitable, is in the hair loss and thinning guide.

Blood tests are recommended before commencing a hair restoration course to exclude systemic causes of hair loss. This is not optional; treating hair loss without understanding its cause risks addressing the symptom while the underlying cause continues.

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Polynucleotides compared to Profhilo

Patients frequently ask how polynucleotides and Profhilo differ and which is more appropriate for them. The detailed comparison is in the Profhilo vs polynucleotides guide, and the broader field of regenerative injectables is covered in the regenerative treatments comparison. The short clinical summary is:

	Polynucleotides (Croma Polyphil)	Profhilo
Primary mechanism	Cellular repair and proliferation via adenosine receptors	Hydration + fibroblast stimulation via HA diffusion
Best suited to	Damaged, thin, or inflamed skin; under-eyes; hair	Generalised quality decline; laxity; dullness
Sessions (first course)	3 to 4, two to four weeks apart	2, four weeks apart
Anti-inflammatory	Yes, direct	Minimal
Volume effect	None	None
Scalp/hair use	Yes (Croma Polyphil)	No

In practice, polynucleotides and Profhilo are often used in sequence or combination. They work through different mechanisms and can address different aspects of the same patient’s skin quality concerns within a single planned programme. The combination is agreed at consultation based on clinical assessment.

A full patient guide to Profhilo is available at The London Road Clinic Profhilo guide.

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The treatment: what to expect

Consultation

All injectable treatments at The London Road Clinic begin with an in-person consultation with our prescribing clinician. Suitability for polynucleotides, the appropriate treatment areas, and the number of sessions recommended are determined at that appointment. For hair restoration specifically, blood test results are requested before treatment begins.

Read more about what to expect at a consultation.

The appointment

A polynucleotide facial treatment takes approximately 30 to 45 minutes. The product is delivered by fine needle or cannula, depending on the treatment area. The under-eye area typically uses a cannula; the face and neck typically use a needle. Topical anaesthetic cream is available on request.

For scalp treatment, a series of small injections distributes the product across the treatment area. This takes approximately 30 minutes.

Some redness and mild swelling at injection sites is normal. Bruising is possible, particularly around the eyes. Both typically resolve within 48 to 72 hours.

The course

A first course for facial treatment is typically three to four sessions, two to four weeks apart, reflecting the pace of the cellular repair process that polynucleotides stimulate. This is more sessions than Profhilo requires. Patients should understand this before committing; the first session is not the full treatment.

Hair restoration courses follow a similar structure, with spacing and session count determined at consultation based on the pattern and extent of thinning.

Aftercare

For 24 hours after treatment:

• Avoid strenuous exercise, saunas and steam rooms.
• Avoid alcohol.
• Do not touch or massage the treated area.
• Avoid make-up directly over injection sites for the remainder of that day.

No extended downtime is required.

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Results: timeline and realistic expectations

The polynucleotide result builds gradually. It is a cellular repair process, not an immediate cosmetic effect, and patients who understand this assess their outcomes more accurately.

Timeframe	What typically happens
Days 1–5	Injection-site reactions resolve. No visible result yet.
Weeks 2–4	Some improvement in skin hydration and texture.
Weeks 4–8	Improved firmness, reduced fine-line visibility, improved luminosity.
Week 8–12	Full result from first course.
Months 6–12	Results maintained; some published data suggests durability up to twelve months in good responders.

For hair restoration, initial changes in scalp condition and reduced shedding are typically noticed within eight to twelve weeks. Visible improvement in hair density is a slower process; patients should not expect dramatic change before four to six months.

What polynucleotides produce:

• Improved skin density, thickness, and structural quality.
• Reduction in fine lines associated with skin thinning and damage.
• Improved under-eye skin quality where thinness and translucency are the concern.
• For hair: reduced shedding, improved follicle activity, improved hair quality in suitable candidates.

What polynucleotides do not produce:

• Added volume. This is not a filler.
• Improvement in pigmentation. That requires a different treatment approach.
• Correction of hair loss caused by an untreated systemic condition.
• Rapid visible results within days.

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Suitability

Polynucleotides are suitable for most adults with skin quality concerns related to ageing, sun damage, or inflammatory history, and for adults experiencing hair thinning in whom systemic causes have been excluded.

Generally suitable:

• Adults noticing skin thinning, reduced firmness, or quality decline in the face, neck, or under-eye area.
• Patients with a history of significant sun exposure or skin damage.
• Patients who have had a good response to other regenerative treatments and wish to extend or deepen the result.
• Adults with hair thinning appropriate for a regenerative injectable approach (assessed at consultation).

Requires careful assessment, or is not suitable:

• Pregnancy and breastfeeding.
• Active skin infection or inflammation in the treatment area.
• Known allergy to fish or fish-derived products: polynucleotides are derived from salmon trout, and a documented fish allergy is a contraindication.
• Autoimmune conditions affecting the skin: discuss at consultation.
• Patients under 18: all cosmetic injectable treatments at The London Road Clinic are for adults only, in line with UK age-restriction legislation introduced in October 2021.

Fish allergy is the most clinically distinctive contraindication for polynucleotides compared to other injectables. It must be disclosed at consultation.

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Pricing and planning

Croma Polyphil polynucleotide injections at The London Road Clinic start from £250 per session. A first course of three sessions starts from £650. Hair restoration courses are priced at consultation based on the area and number of sessions required. Prices include VAT.

Full pricing details are on the Polynucleotides treatment page.

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