PRP vs Polynucleotides for Hair: Which Is Right for You?

PRP (platelet-rich plasma) and polynucleotides (Croma Polyphil) are both injectable treatments used at The London Road Clinic for hair restoration. PRP uses the patient’s own concentrated platelets to deliver growth factors to the scalp. Polynucleotides deliver purified DNA fragments that stimulate cellular repair and improve scalp microcirculation. Both require blood tests before starting a course. The right choice depends on the pattern and cause of hair loss, the scalp’s inflammatory state, and the patient’s clinical history.

What each treatment is

PRP for hair

Platelet-rich plasma (PRP) is produced from the patient’s own blood. A blood draw is taken at the clinic, placed in a centrifuge that separates the blood components, and the platelet-rich fraction is isolated and prepared for injection. This process concentrates the platelets to approximately three to five times their normal blood concentration.

Platelets are best known for their role in clotting, but they also contain alpha granules loaded with growth factors including platelet-derived growth factor (PDGF), TGF-beta, vascular endothelial growth factor (VEGF), epidermal growth factor (EGF) and insulin-like growth factor (IGF). When injected into the scalp at hair follicle depth, these growth factors stimulate follicle activity, promote angiogenesis (new blood vessel formation to supply the follicle), and have been shown in multiple studies to extend the anagen (active growth) phase of the hair cycle.

PRP is autologous: the material being injected is derived from the patient’s own body, which eliminates the possibility of allergic reaction to the treatment substance itself.

Polynucleotides for hair (Croma Polyphil)

Polynucleotides are purified DNA fragments derived from salmon trout, processed to remove proteins that could cause immune reactions. At The London Road Clinic, we use Croma Polyphil, manufactured by Croma Pharma. Injected into the scalp, polynucleotides act via two mechanisms: binding to adenosine receptors to reduce scalp inflammation, and stimulating fibroblast proliferation to improve tissue quality and microcirculation in the dermal papilla, the structure that supplies each hair follicle with nutrients.

The anti-inflammatory mechanism is the key clinical differentiator from PRP. Where scalp inflammation is a component of hair loss, the adenosine receptor agonism of polynucleotides addresses it directly. PRP’s growth factor delivery does not have the same specific anti-inflammatory action.

Polynucleotides are a pharmaceutical product rather than autologous. Patients with a documented fish allergy cannot receive them, as they are salmon-derived.

Both treatments are discussed in detail in the polynucleotides patient guide and the regenerative treatments comparison.

Blood tests before either treatment

Blood tests are recommended before commencing a hair restoration course with either PRP or polynucleotides. This is not a formality. Hair loss has systemic causes including thyroid dysfunction, iron deficiency, B12 deficiency, hormonal imbalance and autoimmune conditions that will not respond to scalp-level injectable treatment regardless of how well the treatment is delivered.

Treating hair loss without understanding its cause is poor clinical practice. At The London Road Clinic, blood tests are recommended before any hair restoration course. Where a systemic cause is identified, it is addressed in parallel (typically via GP referral) before or alongside scalp treatment.

Head-to-head comparison

The evidence: an honest account

PRP for hair restoration has the more established evidence base of the two. Multiple randomised controlled trials have demonstrated improvements in hair count, hair thickness, hair shaft diameter and patient-reported outcomes in androgenetic alopecia with PRP, compared to placebo or control. The effect size is meaningful but not uniform: response varies between patients and response to PRP does not predict response to other treatments.

Polynucleotides for hair have a solid biological rationale and growing clinical data, particularly from European research. The evidence base is less mature than PRP specifically for hair, though the evidence for polynucleotides in skin quality applications is well-established and the scalp mechanisms are consistent with the dermal mechanisms observed in facial treatment.

The honest clinical position is that where a patient has androgenetic alopecia and no contraindication to either treatment, PRP has the stronger published evidence base for that specific diagnosis. Where scalp inflammation is a prominent feature, polynucleotides have a specific mechanism that PRP lacks. Where fish allergy precludes polynucleotides, PRP is the appropriate choice by default.

Choose PRP if

• Your hair loss is consistent with androgenetic alopecia (male or female pattern) and is at an early to moderate stage.
• You prefer an autologous treatment with no foreign substance being injected.
• You have no practical objection to a blood draw at each appointment.
• Systemic blood tests have excluded underlying causes and hair loss treatment is clinically appropriate.
• The evidence base is a primary decision factor for you; PRP has more published hair-specific RCT data.

Choose polynucleotides if

• You have a documented fish allergy. PRP remains the option; polynucleotides are contraindicated.
• Scalp inflammation is a prominent feature of your hair concern; polynucleotides’ direct anti-inflammatory mechanism is clinically relevant here.
• You prefer a product-based approach without a blood draw at each appointment.
• You are already using polynucleotides for skin quality and wish to extend treatment to the scalp within the same programme.
• Blood tests have identified a systemic cause being managed in parallel, and a scalp treatment is appropriate alongside that management.

Can they be combined?

Yes. PRP and polynucleotides act through complementary mechanisms: PRP delivers growth factors that stimulate follicle activity and angiogenesis; polynucleotides reduce inflammation and improve the cellular environment of the dermal papilla. Some patients at The London Road Clinic use both in an alternating programme, particularly where both the growth factor stimulus and the anti-inflammatory action are clinically indicated.

Alternating sessions, rather than combining at the same appointment, is the standard approach. The programme structure is agreed at consultation based on the clinical picture.

The broader context of regenerative injectables for hair and skin is covered in the regenerative treatments comparison and the hair loss and thinning guide. This article covers the scalp. The same two treatments compared for facial skin quality, including under-eye and mid-face, are in the PRP vs polynucleotides comparison for the face.

What neither can do

Both PRP and polynucleotides work by supporting the environment and activity of existing hair follicles. Neither can restore function to follicles that have been permanently destroyed by scarring alopecia (cicatricial alopecia), where the follicle structure has been irreversibly damaged by inflammation or fibrosis. Assessment of the type of alopecia is part of the consultation.

Neither treatment produces results equivalent to surgical hair transplantation for patients with advanced hair loss and significant follicle miniaturisation. For patients whose hair loss has progressed to a stage where non-surgical approaches have meaningful limitations, surgical assessment is the more appropriate conversation.

Read more about what to expect at a consultation at The London Road Clinic.

Frequently asked questions