What is scalp platelet‑rich plasma (growth‑factor concentrate) for androgenetic alopecia, how is it administered, what are its efficacy, side effects, contraindications, and how does it compare to first‑line treatments such as minoxidil and finasteride?

Growth Factor Concentrate (PRP/PRF) for Androgenetic Alopecia

Platelet-rich plasma (PRP) and growth factor concentrate (GFC) are effective second-line treatments for androgenetic alopecia that should be combined with topical minoxidil 5% for optimal results, particularly in patients who show suboptimal response to first-line monotherapy. 1, 2

What is Growth Factor Concentrate?

Growth factor concentrate refers to autologous platelet concentrates derived from the patient's own blood, primarily including:

• Platelet-Rich Plasma (PRP): Contains concentrated platelets (1 to 1.5 million platelets per microliter) with growth factors including platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and transforming growth factor beta (TGF-β) 1, 3
• Platelet-Rich Fibrin (PRF): A newer generation concentrate with theoretical advantages including sustained growth factor release, though clinical evidence remains limited compared to PRP 4, 2
• Growth Factor Concentrate (GFC) tubes: Specialized tubes containing 9-10 mL of peripheral blood without anticoagulants, processed via centrifugation to achieve the same therapeutic platelet concentration as PRP 1

Mechanism of Action

PRP works through multiple pathways to stimulate hair growth:

• Induces proliferation of dermal papilla cells and increases vascularization of perifollicular tissue 2, 5
• Accelerates the telogen-to-anagen (resting-to-growth) phase transition 2, 5
• Increases proliferative activity of hair follicle cells (measured by β-catenin, CD34, Ki67 markers) 4
• Promotes neocollagenesis and increases the number of basal keratinocytes 4
• Stimulates bulge stem cell niches and reduces perivascular inflammatory infiltrate 6

How PRP/GFC is Administered

Preparation Protocol

Use the manual double-spin method without activation — nonactivated PRP shows 31% greater improvement in hair density compared to activated PRP 2, 5

Target platelet concentration: 1 to 1.5 million platelets per microliter 1, 2

Patient Preparation

• Patient must shampoo and detangle hair before each session with no hair products applied 2, 5
• Apply pharmaceutical-grade topical anesthetic cream before injection due to significant pain associated with the procedure 1, 2, 5

Injection Technique

• Dose: 5-7 mL of PRP per session 1, 2
• Injection rate: 0.05 to 0.1 mL/cm² 1, 2
• Needle: 30-gauge × 4 mm needles to minimize discomfort 1, 2
• Technique: 90-degree angle, 2-4 mm depth, injections spaced 1 cm apart 1, 2

Alternative Application Method

Microneedling with topical application of PRP or CGF gel may be superior to injection technique in terms of anagen phase promotion, telogen reduction, and average hair length 4, 3

Treatment Schedule

Initial Treatment Phase

Perform 3-5 treatment sessions spaced exactly 1 month apart 1, 2, 5

Maintenance Phase

After completing the initial series, maintain with 1 session every 6 months 1, 2, 5

Timeline for Results

• A 25% improvement in hair density at 2 months predicts sustained response at 6 months 2, 5
• Maximum response with PRP typically occurs by 6 months 2, 5

Efficacy: How It Compares to First-Line Treatments

First-Line Treatments Remain Standard

Oral finasteride 1 mg daily or topical minoxidil 5% twice daily (or once daily for women) are first-line monotherapy options, with finasteride demonstrating superior efficacy in head-to-head trials for men 1, 2

PRP Monotherapy vs. Minoxidil Monotherapy

• PRP monotherapy is more effective than minoxidil monotherapy in most studies, though one study found them equally effective 4
• PRP increases hair density by approximately 12.76% over baseline at 16 weeks compared to placebo (+0.99%) 7
• Mean hair count increases from 71 to 93 follicular units per cm² after four PRP sessions 8

Combination Therapy Shows Superior Results

The combination of PRP with topical minoxidil 5% shows the highest increase in hair density in comparative studies — this is the most effective treatment modality 4, 1, 2, 5

Specific outcomes with combination therapy:

• 57% median increase in terminal hair density versus 48% with minoxidil alone at 32 weeks 2
• 83% of patients achieve a negative hair pull test (indicating reduced hair fragility) after combination treatment 2
• Combination therapy is significantly more effective than minoxidil monotherapy 2

When to Add PRP

Add PRP therapy for patients showing suboptimal response to first-line treatments or those seeking enhanced results 1, 2, 5

PRP is particularly useful as adjuvant therapy in poor responders to conventional therapy 4

Side Effects and Tolerability

Pain is the Primary Concern

• Significant pain occurs during PRP injections, making minoxidil better tolerated than PRP 4
• Pharmaceutical-grade topical anesthetic cream is strongly recommended and should be applied before every injection 1, 2, 5

Safety Profile

PRP is a safe therapeutic option created from autologous blood, minimizing risk of allergic reactions or disease transmission 9

No serious adverse events are reported in clinical trials 8, 6

Contraindications

While the evidence does not explicitly detail absolute contraindications, the following clinical considerations apply:

• Active scalp infection or inflammation at injection sites
• Platelet dysfunction disorders or thrombocytopenia
• Patients on anticoagulation therapy (relative contraindication requiring case-by-case assessment)
• Active cancer (theoretical concern regarding growth factor stimulation)

Critical Factors for Treatment Success

Higher Platelet Concentration Matters

Higher platelet concentrations (1-1.5 million/µL) correlate with greater improvements in hair density, follicle diameter, and terminal hair density 4, 1, 5

Common Causes of Treatment Failure

Low platelet concentration, inadequate injection volume, or insufficient treatment frequency leads to PRP treatment failure 4, 1, 2

Additional factors affecting outcomes:

• Individual genetic factors significantly influence response to all platelet concentrate therapies 4, 1
• Insufficient treatment duration leads to suboptimal outcomes — some patients require extended therapy beyond the initial 6 months 2, 5
• The efficacy of all treatments decreases with increasing severity and duration of alopecia, making early intervention essential 5

Monitoring Treatment Response

Objective Assessment Methods

Use multiple objective measures rather than relying on patient perception alone 5:

• Standardized before-and-after photographs at consistent lighting and angles 4, 1, 2, 5
• Trichoscopy to evaluate hair density per cm² and hair shaft diameter 4, 1, 5
• Hair pull tests to assess hair fragility 4, 2, 5
• Patient self-assessment questionnaires to evaluate satisfaction and quality of life impact 4, 1, 5

Key Indicators of Positive Response

• Increased hair density per cm² 4, 1
• Increased hair shaft diameter 4, 1, 5
• Decreased proportion of telogen (resting phase) hairs 2, 5
• Improved patient satisfaction scores 1, 5

Evaluation Timeline

• Evaluate response at 4-6 months using standardized photography and trichoscopy 5
• Reassess at 12 months with comprehensive evaluation including hair counts and patient satisfaction 5

Emerging Alternative: Platelet-Rich Fibrin (PRF)

Theoretical Advantages

PRF has theoretical advantages over PRP including:

• Lower cost and easier preparation 2
• More sustained release of growth factors, functioning as both scaffold and reservoir 4
• No requirement for anticoagulants 1

Limited Evidence Base

The evidence base for PRF specifically remains limited, with most high-quality studies evaluating PRP, and standardized protocols for PRF are still needed 1

Preliminary studies show PRF demonstrates safety and efficacy comparable to PRP, with statistically significant improvements in hair density at 2,3, and 6 months follow-up 4, 2

Patients with greater disease severity at baseline tend to achieve larger improvements after PRF treatment 4

Clinical Algorithm for Treatment

Step 1: Initiate First-Line Therapy

Start with topical minoxidil 5% (once daily for women, twice daily for men) or oral finasteride 1 mg daily for men 1, 2, 5

Step 2: Evaluate Response at 4-6 Months

Use standardized photography and trichoscopy to assess treatment response 5

Step 3: Add PRP for Suboptimal Response or Enhanced Results

For patients showing inadequate response or seeking optimal outcomes, add PRP therapy using the protocol detailed above 2, 5

Step 4: Continue Combination Therapy Indefinitely

Both minoxidil and PRP maintenance must be continued indefinitely, as discontinuation leads to reversal of hair growth benefits 2, 5

Step 5: Long-Term Monitoring

Reassess at 12 months with comprehensive evaluation, and maintain PRP sessions every 6 months after initial treatment series 2, 5

Critical Clinical Pitfalls to Avoid

• Inadequate follow-up to assess treatment response results in missed opportunities to adjust therapy 2, 5
• Using activated PRP when nonactivated shows superior results 2, 5
• Insufficient injection volume or treatment frequency causes treatment failure 1, 2
• Failing to use topical anesthetic leads to poor patient tolerance and potential treatment discontinuation 1, 2, 5
• Not combining with minoxidil when combination therapy shows significantly superior results 4, 1, 2