The Science Behind PRP: How Growth Factors Revitalise Hair Follicles

This article aims to explain the science behind PRP therapy for hair, including how growth factors interact with hair follicles, what the treatment involves, who may be suitable, and what realistic expectations look like. As with any aesthetic procedure, individual assessment by a qualified practitioner is essential before considering treatment.

If you want the procedural view alongside this science explainer, see the PRP injection step-by-step walkthrough.

Platelet-rich plasma (PRP) therapy is a procedure in which a small volume of the patient's own blood is drawn, processed to concentrate the platelet content, and reintroduced into the scalp via precise injections. The concentrated platelets release growth factors that may help support the health and activity of hair follicles, making PRP a subject of ongoing clinical interest for patients experiencing certain types of hair thinning.

PRP therapy is considered an autologous treatment — meaning it uses the patient's own biological material — which is one of the reasons it has become a point of interest in hair restoration discussions. The treatment does not involve synthetic chemicals or foreign substances, and it draws on the body's own regenerative capacity.

It is worth noting that PRP is not a cure for hair loss, and it is not suitable for all types or causes of alopecia. Its potential benefits are most commonly explored in the context of androgenetic alopecia (pattern hair loss) and, in some cases, certain other forms of hair thinning. The suitability of PRP for any individual depends entirely on a thorough assessment by a qualified medical practitioner who can evaluate the underlying cause of hair loss before recommending a course of action.

PRP therapy works by concentrating platelets from the patient's own blood and injecting them into the scalp. These platelets release growth factors — including PDGF, VEGF, and EGF — that may stimulate cellular activity around hair follicles, potentially prolonging the active growth phase, improving follicle size, and supporting the scalp's local environment. Results vary by individual.

To appreciate why PRP therapy is studied in the context of hair loss, it helps to understand the natural biology of hair growth. Each hair follicle undergoes a continuous cycle consisting of three primary phases:

Anagen (growth phase): The active period during which the hair shaft grows. This phase can last between two and seven years depending on genetics and other factors.

Catagen (transition phase): A brief period lasting approximately two to three weeks during which the follicle shrinks and detaches from its blood supply.

Telogen (resting phase): A period of relative inactivity, after which the hair sheds and the follicle ideally re-enters the anagen phase.

In people experiencing hair thinning, the anagen phase often becomes progressively shorter, resulting in finer, shorter hairs over time. Follicles may also miniaturise — a process closely associated with androgenetic alopecia — leading to reduced hair density and coverage.

The dermal papilla, a specialised cluster of cells at the base of each follicle, plays a central role in regulating the hair cycle. It communicates with the surrounding stem cells and blood supply to initiate and sustain growth. This is the area that growth factors from PRP are thought to influence.

Platelets are best known for their role in blood clotting, but they also contain a rich reservoir of signalling proteins called growth factors. When platelets are activated — as they are during the PRP preparation process — they release these growth factors, which instruct surrounding cells to carry out specific biological tasks.

The growth factors most relevant to hair follicle biology include:

Platelet-Derived Growth Factor (PDGF): Supports cell proliferation and the recruitment of new cells to the follicle environment.

Vascular Endothelial Growth Factor (VEGF): Encourages the formation of new blood vessels (angiogenesis), potentially improving blood flow and nutrient delivery to follicles.

Epidermal Growth Factor (EGF): Plays a role in skin and follicle cell regeneration and differentiation.

Insulin-Like Growth Factor (IGF-1): May help sustain the anagen phase and support dermal papilla cell activity.

Transforming Growth Factor Beta (TGF-β): Involved in tissue remodelling and regulation of the hair cycle.

When PRP is introduced into the scalp at the level of the follicles, these growth factors are thought to create a more supportive environment for follicular activity — potentially stimulating dormant follicles, extending the growth phase, and improving the overall quality and calibre of the hair produced. The scientific evidence supporting these mechanisms is evolving, and whilst clinical studies show promising findings, results vary between individuals and are not guaranteed.

Understanding what the treatment involves can help patients approach a consultation with informed expectations. The process typically unfolds in the following stages:

Blood Draw A small volume of blood — usually between 20 and 60 millilitres — is taken from the patient's arm, similar to a standard blood test.

Centrifugation The blood sample is placed in a centrifuge machine that spins at high speed, separating the blood into its component layers. This concentrates the platelets into a smaller volume of plasma, producing the PRP solution.

Activation In some protocols, the platelets are activated prior to injection using calcium chloride or another agent, prompting early release of growth factors.

Scalp Injection The PRP is injected across the scalp using a fine needle, with particular attention to areas of concern. Some practitioners use a topical numbing agent beforehand to manage discomfort.

The treatment is typically carried out in a clinical setting and does not usually require general anaesthesia or significant downtime. The number of sessions recommended will depend on individual assessment, the degree of hair loss, and the practitioner's clinical judgement.

PRP therapy for hair loss is not universally suitable, and this point is important. The treatment tends to be most commonly discussed in the context of:

Androgenetic alopecia: The most common form of hair loss in both men and women, characterised by a genetically influenced pattern of thinning.

Patients in earlier stages of hair thinning: PRP is generally thought to be more applicable when follicles are still present and active, rather than in cases of advanced scarring alopecia where follicles may have been permanently damaged.

Patients seeking a complementary approach: Some practitioners explore PRP alongside other evidence-based options such as topical minoxidil or oral finasteride, depending on individual circumstances.

PRP may not be appropriate for patients with certain blood disorders, those on anticoagulant medications, individuals with active scalp infections or inflammation, or those with particular systemic health conditions. It is also important to understand that the cause of hair loss must be properly identified before any treatment is considered — this requires a professional assessment, which may include a clinical examination and, in some cases, blood tests.

No reputable practitioner will recommend PRP without first conducting a thorough individual assessment.

For women-specific context, PRP for thinning hair in women expands on hormonal and diagnostic considerations.

It is essential to approach PRP therapy with balanced, realistic expectations. The following considerations reflect current clinical understanding:

Potential benefits that have been explored in clinical research include:

Increased hair density in areas of diffuse thinning

Improvement in hair shaft diameter and overall hair quality

Possible prolongation of the anagen (growth) phase

A generally well-tolerated procedure with minimal recovery time

Realistic expectations:

Results, where they occur, are typically gradual and may not become visible until several weeks or months after treatment

Multiple sessions are usually required as part of an initial programme, followed by potential maintenance treatments

Individual response varies considerably — not all patients experience the same degree of improvement

PRP is unlikely to restore hair in areas where follicles are no longer present

Limitations to be aware of:

The evidence base, whilst growing, is still evolving — high-quality randomised controlled trials remain limited

PRP does not address the underlying genetic or hormonal causes of androgenetic alopecia

Results are not permanent, and ongoing treatment may be needed to maintain any improvements

Cost and commitment to multiple sessions are practical considerations

A candid discussion with a qualified practitioner about your specific situation, expectations, and medical history is the most important step before deciding whether PRP is appropriate for you.

There are a number of situations in which seeking a professional assessment may be a sensible and well-informed step. These are not indicators that treatment is necessary — only that speaking to a qualified practitioner could provide clarity:

Gradual thinning of the hairline or crown that has become noticeable over months or years

Increased hair shedding beyond what seems normal during washing or brushing

Reduced overall hair density or a visible widening of the hair parting

Post-partum or post-illness hair loss that has not resolved naturally over time

Curiosity about non-surgical hair restoration options and how they might fit into a broader approach

A professional consultation provides an opportunity to understand the likely cause of your hair concerns, discuss whether any treatment — including PRP — is appropriate, and receive honest, evidence-informed guidance. Pantaleo Clinic in London offers personalised aesthetic consultations where patients can discuss their concerns in a calm, unhurried environment.

PRP is sometimes discussed alongside other aesthetic treatments that support tissue regeneration and skin quality. It is worth being aware of how it relates to these alternatives, as some patients explore combination approaches:

Polynucleotides (PDRN) Polynucleotide treatments, derived from purified DNA fragments, have gained interest as a skin and scalp rejuvenation option. Like PRP, they are thought to support cellular regeneration and tissue repair. Some practitioners discuss them in a similar context to PRP, though they are distinct treatments with different mechanisms. You can explore skin booster treatment information to understand more about regenerative skin-quality approaches.

Mesotherapy and Scalp Micronutrient Delivery Some practitioners offer scalp mesotherapy — the injection of vitamins, minerals, or other compounds — as a complementary approach to hair health, though the evidence base varies significantly between specific formulations.

Topical and Medical Hair Loss Treatments Licensed medical treatments such as minoxidil and finasteride remain among the most extensively studied options for androgenetic alopecia. PRP is not a replacement for these treatments in appropriate candidates, and a practitioner may discuss whether a combined approach is relevant to your situation.

The most important principle is that no single treatment should be chosen in isolation from a full clinical picture.

Following a PRP session, a qualified practitioner will provide specific aftercare guidance tailored to your individual treatment. General considerations that are commonly discussed include:

Avoiding vigorous scalp washing for 24–48 hours following the procedure

Refraining from applying styling products, dry shampoo, or chemical treatments to the scalp for a short period post-treatment

Sun protection: Protecting the scalp from direct sun exposure following treatment is often advised

Avoiding strenuous exercise for 24 hours, as this may increase blood flow and potentially affect the treated area

Staying well hydrated to support overall tissue health

Following any additional personalised guidance provided by your treating practitioner — this takes priority over general advice

It is also worth considering broader lifestyle factors that support hair and scalp health, including a balanced diet rich in protein, iron, zinc, and vitamins such as biotin and vitamin D (subject to appropriate testing), adequate sleep, and stress management — all of which can influence the hair growth cycle.

PRP therapy uses the patient's own blood to create a concentrated solution of growth factors that may support hair follicle activity when injected into the scalp.

The scientific basis is evolving — clinical research is ongoing, and whilst findings are encouraging in certain patient groups, results are not guaranteed and vary between individuals.

Suitability is not universal — PRP is not appropriate for all types or causes of hair loss, and a professional assessment is essential before considering treatment.

Realistic expectations matter — improvements, where they occur, are typically gradual and may require multiple sessions and potential ongoing maintenance.

PRP does not address the root cause of androgenetic alopecia — it may support the scalp environment, but it does not alter underlying genetic or hormonal factors.

A qualified consultation is the most important first step — understanding the cause of your hair concerns is foundational to any informed treatment decision.

PRP therapy represents a scientifically grounded area of interest in hair restoration medicine, drawing on the body's own biological signalling mechanisms to potentially support follicle health. The growth factors released by concentrated platelets — including PDGF, VEGF, EGF, and IGF-1 — are thought to create a more favourable environment for hair follicle activity, and clinical research continues to explore their role in addressing certain types of hair thinning.

That said, PRP is not a universal solution, not a cure for hair loss, and not a treatment to pursue without proper investigation into the underlying cause of your concerns. The evidence base is still developing, results vary considerably between individuals, and realistic expectations are an essential part of any informed decision-making process.

If you are considering PRP therapy for hair loss, or if you simply want to understand your options more clearly, the most valuable step you can take is to seek a professional consultation with a qualified practitioner who can assess your specific situation. Understanding the type and cause of your hair loss is foundational — and that understanding can only come through individual clinical assessment.

For patients in London exploring their options, the PRP injections treatment page is a practical next step before booking.

Treatment suitability, risks, and expected outcomes should always be assessed individually during a professional consultation.