UltraEstetic Aesthetic Clinic

Hair loss affects, according to European prevalence data, approximately 50% of men over 50 and up to 40% of women by around the age of 60. Most forms — androgenetic alopecia, telogen effluvium, post-stress alopecia and the diffuse patterns linked to nutritional or hormonal deficiencies — now benefit from a broader range of therapeutic options than they did ten or fifteen years ago. Among these, scalp injections with polynucleotides are a relatively recent approach that has drawn interest in both aesthetic medicine and clinical trichology.

This article explains what these injectable DNA fragments are, how they act at the level of the hair follicle, who is a candidate, and how they compare to other commonly used treatments for hair loss.

Hair Loss in Brief: the Common Mechanisms

Before discussing treatment, it helps to understand the phenomenon. The hair follicle goes through successive growth cycles — the anagen phase (active growth, 2-7 years), the catagen phase (transition, a few weeks) and the telogen phase (resting, 2-4 months), followed by hair shedding and the return to anagen.

Pathological hair loss occurs when:

• The percentage of hairs in telogen rises excessively (telogen effluvium after childbirth, febrile illness, major stress or rapid weight loss).
• Follicles undergo progressive miniaturization under hormonal influence (androgenetic alopecia, both male and female pattern).
• Chronic inflammation affects the follicle (cicatricial alopecias, lichen planopilaris, frontal fibrosing alopecia).
• Nutritional deficiencies or thyroid imbalance disrupt the hair cycle.

The effectiveness of any treatment — polynucleotides included — depends on the correct identification of the underlying cause.

What Polynucleotides Are and Where They Come From

Polynucleotides are short chains of highly purified DNA, generally extracted from marine sources — trout gonads or salmon sperm. The purification process removes proteins and potential allergens, leaving only fragments of nucleic acid biocompatible with human tissue.

In medicine, these fragments were initially used in the 1980s to accelerate the healing of burns and post-surgical scars. Their application in trichology came later, as purification protocols allowed safe scalp injection.

Commercially, they are available under various proprietary names (Plinest, Newest, Mastelli, Plinest Hair) — the active substance is essentially the same across brands.

How Polynucleotides Act on the Hair Follicle

The mechanism is not limited to a single pathway but involves several parallel processes, each relevant to the follicular cycle:

Reactivation of perifollicular dermal fibroblasts — the cells in the follicle‘s dermal papilla are stimulated to produce extracellular matrix and growth factors that support the anagen phase.

Local neoangiogenesis — the formation of new capillaries around follicles improves oxygenation and nutrition, two key factors for thick, healthy hair. Doppler imaging studies show increased microcirculation density after a series of injections.

Anti-inflammatory effect — in alopecias with an inflammatory component, polynucleotides have clinically demonstrated the capacity to reduce the perifollicular inflammatory infiltrate, a known factor in miniaturization.

Hydrating environment for the follicle — the capacity of polynucleotides to bind water at the dermal level creates a more favorable environment for the metabolic activity of follicular cells.

The clinically visible result in documented protocols is an increase in hair density (more hairs per cm²), thicker hair shafts (the diameter of existing hairs increases) and reduced excessive shedding in the following weeks.

Who Is a Candidate for Scalp Polynucleotides

Classic indications include:

• Early to moderate androgenetic alopecia in men (Norwood scale I-IV) and women (Ludwig scale I-II).
• Prolonged telogen effluvium, when shedding persists more than six months after the triggering factor.
• Non-hormonal diffuse alopecia, after correction of nutritional deficits (iron, vitamin D, zinc, B vitamins).
• Post-stress or post-COVID alopecia, with persistent shedding beyond four to six months.
• Patients already on minoxidil or finasteride, as adjuvant therapy for improved outcomes.
• Pre- or post-hair transplant patients, as preparatory treatment for the scalp or for optimization of the grafts.

The precise indication is set after a complete trichological evaluation, ideally with trichoscopy — examination with polarized light and magnification of the follicles and hair density, which quantifies the degree of miniaturization. Polynucleotides are not useful in advanced cicatricial alopecias, where the follicle has already been destroyed.

How a Polynucleotide Scalp Session Works

The usual steps of a scalp procedure:

Initial consultation — complete history (family history of balding, medical background, supplements, stress, diet), clinical and trichoscopic examination, standardized photographs, blood tests when indicated (ferritin, vitamin D, zinc, thyroid hormones, iron panel).

Preparation — scalp cleansing and, optionally, topical anesthesia or nerve block for more sensitive zones. Discomfort is moderate and tolerable without anesthesia for most patients.

Injection — polynucleotides are administered in the dermis and at the perifollicular level, using a fine needle or a microcannula. The typical dose is 2-3 ml per session, distributed across the affected area. In patients with Norwood III-IV, up to 4 ml may be used.

The session may be combined with growth-factor mesotherapy, exosomes or RF microneedling — combined protocols that maximize biological absorption and effect.

Number of sessions — the standard protocol is 4-6 sessions at 3-4 week intervals, followed by a maintenance session at 4-6 months. First visible results (reduction of shedding) appear at 4-6 weeks; density gains become visible at 3-4 months; the maximum result, at 6 months.

Post-procedure recommendations — no scalp washing for 24 hours, no sauna or very hot baths for 48 hours, no intense sun exposure on the injected area for 5-7 days.

For an example of a polynucleotide treatment applied to the scalp for hair loss at an aesthetic medicine clinic, the structure of the protocol and the adjustments by alopecia stage and type are detailed in the clinic‘s treatment page.

Polynucleotides vs Other Hair Loss Treatments

The most frequent comparisons patients ask about:

Polynucleotides vs PRP (Platelet-Rich Plasma) — PRP uses the patient‘s own plasma, centrifuged to concentrate platelets and autologous growth factors. The advantage of PRP is its autologous source (zero allergic risk); the disadvantage is the quality variability between patients (it depends on the plasma‘s richness in platelets). Polynucleotides have a standardized concentration but come from an external source. In many modern protocols, the two are combined (PRP in one session, polynucleotides in another), benefiting from complementary mechanisms.

Polynucleotides vs topical minoxidil — minoxidil works by prolonging the anagen phase and by local vasodilation, applied daily. The advantage: no injections, available at the pharmacy. Disadvantages: requires permanent daily application, local side effects (irritation, facial hypertrichosis in women) and significant rebound on discontinuation. Polynucleotides are administered in courses (4-6 sessions) with semi-annual maintenance, without daily application.

Polynucleotides vs oral finasteride — finasteride inhibits the 5-alpha-reductase enzyme, reducing the production of DHT, the hormone involved in male androgenetic alopecia. Efficacy demonstrated in multiple studies, but with potential systemic side effects (libido, mood, in some reported cases persistent). Polynucleotides act locally, without systemic hormonal effects. The two options are frequently combined in men with documented androgenetic alopecia.

Polynucleotides vs hair transplant — the transplant (FUE, FUT) moves follicles from the donor area (occipital) to the affected area. It is a surgical solution for already-established balding, in advanced stages. Polynucleotides are useful pre-transplant (preparation of donor and recipient skin) and post-transplant (graft optimization), but do not replace the transplant in advanced alopecias.

Polynucleotides vs classic hair mesotherapy — mesotherapy with cocktails of vitamins, peptides and amino acids is an older option, with more limited clinical evidence. Polynucleotides have a better-documented cellular mechanism and supportive imaging studies.

Limits, Contraindications and When Polynucleotides Are Not Indicated

Absolute contraindications:

• Pregnancy and breastfeeding.
• Known fish allergy (due to the marine source).
• Active autoimmune disease with cutaneous manifestations.
• Active scalp infections.
• Coagulopathies or uncontrolled anticoagulant therapy.

Situations in which polynucleotides have reduced or no efficacy:

• Cicatricial alopecias (lichen planopilaris, discoid lupus, frontal fibrosing alopecia in advanced stages) — the follicle has been destroyed and replaced by scar tissue.
• Norwood VI-VII stages — residual follicular density too low for a meaningful biological response; transplant is generally the only effective solution.
• Uncorrected nutritional deficits — without addressing the primary cause (iron-deficiency anemia, severe vitamin D deficit, hypothyroidism), the effects of any local treatment are limited.

An honest evaluation of the stage and type of alopecia before starting treatment prevents unrealistic expectations and unnecessary costs.

Frequently Asked Questions about Polynucleotides for Hair Loss

When do results appear after scalp polynucleotide treatment? Reduction in excessive shedding appears at 4-6 weeks after the first session. Density gains become visible at 3-4 months, and the maximum result is observed at 6 months after the final session of the protocol.

How many sessions are needed? The standard protocol is 4-6 sessions at 3-4 week intervals. For moderate androgenetic alopecia, more sessions may be needed. Maintenance is achieved with one session every 4-6 months.

Do polynucleotides work in women? Yes, particularly in female androgenetic alopecia (Ludwig scale I-II) and in prolonged telogen effluvium. Women often respond better than men in early stages because the follicle is not yet fully miniaturized.

Can I continue minoxidil or finasteride in parallel? Yes. Polynucleotides are frequently used as adjuvant therapy. The combination is often recommended by specialists for more consistent results, especially in moderate stages.

Are they safe for patients after a hair transplant? Yes — they are even indicated as graft-optimization treatment. They can typically be administered 2-4 weeks post-procedure, with the surgeon‘s clearance.

What is the difference between injectable polynucleotides and topical serums with peptides? Topical serums do not penetrate to the depth required to act on the hair follicle. Polynucleotides injected directly into the dermis at the follicular level have a clinically documented biological impact. Topical serums are complementary, not a substitute.