A comprehensive literature search was conducted using PubMed, Embase, Scopus, and Web of Science to identify relevant clinical studies published between January 2020 and January 2026. The restriction to studies published from 2020 onward was applied to capture the most recent evidence reflecting advances in PRP preparation techniques and clinical applications.

Only studies published in English were included due to resource constraints. Online-ahead-of-print articles available within the search period were also considered eligible.

Although this study is a narrative review, selected elements of PRISMA-guided reporting were incorporated to enhance methodological transparency and reproducibility.

Study screening was conducted by two independent reviewers. Titles and abstracts were independently screened for relevance, followed by full-text assessment of eligible articles. Discrepancies between reviewers were resolved through discussion and consensus.

The database search initially identified 243 records across PubMed, Embase, Scopus, and Web of Science. After removal of duplicate articles, 210 studies remained for title and abstract screening. Studies that did not meet the inclusion criteria, including non-clinical studies, animal experiments, review articles, and studies unrelated to platelet-rich plasma therapy for hair loss, were excluded during this stage.

A total of 72 full-text articles were assessed for eligibility. After full-text evaluation, 20 studies were excluded due to insufficient clinical outcome data, unclear PRP protocols, or lack of extractable efficacy or safety outcomes. Ultimately, 52 clinical studies were included in this narrative review and were used for qualitative synthesis.

Included studies met the following criteria: 1) evaluated PRP as a monotherapy or adjunctive therapy for hair restoration; 2) focused on human subjects with any type of hair loss (AGA, AA, TE, or other less common forms); 3) were clinical studies (randomized controlled trials, prospective cohort studies, retrospective cohort studies, or pilot studies); 4) reported quantitative data on therapeutic efficacy (e.g., hair density, response rate) or safety (e.g., adverse events); and 5) were published between 2020 and 2026. Exclusion criteria included: 1) in vitro or animal studies; 2) case reports or case series with fewer than 10 patients; 3) studies evaluating PRP in combination with emerging therapies (e.g., stem cell therapy, exosomes) without a separate PRP group; and 4) studies with incomplete or unextractable data on efficacy or safety.

Two independent reviewers extracted data from the included studies using a standardized data extraction form, which included information on study design, sample size, patient demographics (age, gender, hair loss subtype, severity), PRP preparation protocol (centrifugation method, platelet concentration, activation method), PRP administration protocol (route, frequency, number of sessions), outcome measures (hair density, hair thickness, response rate, patient satisfaction), safety outcomes (adverse events, severity, resolution time), and follow-up duration. Discrepancies between reviewers were resolved through consensus. Data were synthesized thematically, focusing on efficacy across hair loss subtypes, safety profile, patient satisfaction, and factors influencing treatment outcomes.

The methodological quality of included randomized controlled trials (RCTs) was assessed using the Cochrane Risk of Bias Tool (RoB 2.0), evaluating domains such as random sequence generation, allocation concealment, blinding, incomplete outcome data, and selective reporting. For non-randomized studies, the Newcastle-Ottawa Scale (NOS) was used to assess study quality based on selection, comparability, and outcome domains. Quality assessment was performed independently by two reviewers, with disagreements resolved through consensus.

Among the included randomized controlled trials, 2 studies were assessed as low risk of bias, 13 as having some concerns, and 4 as high risk of bias according to the Cochrane Risk of Bias Tool (RoB 2.0). Common limitations included lack of blinding and incomplete reporting of allocation concealment.

For non-randomized studies, quality assessment using the Newcastle-Ottawa Scale indicated that 6 studies were of high quality, 19 of moderate quality, and 8 of low quality. Common limitations included small sample sizes, short follow-up duration, and inadequate control for confounding variables.

Overall, the included studies demonstrate moderate methodological quality, with common limitations related to lack of blinding, small sample sizes, and short follow-up duration, which should be considered when interpreting the reported efficacy outcomes.

Before Platelet-rich plasma (PRP) is prepared from autologous blood using centrifugation techniques that concentrate platelets above baseline levels, enriching plasma with growth factors essential for hair follicle regeneration. Preparation protocols vary considerably across studies, particularly regarding single-spin versus double-spin methods, with double-spin techniques generally producing higher platelet concentrations and potentially superior clinical outcomes [8]. Reported platelet concentrations range from approximately 1.0 × 10⁶/μL to over 5.0 × 10⁶/μL, and higher platelet counts have been associated with improved hair regrowth in androgenetic alopecia [9]. Differences in leukocyte content (leukocyte-rich vs. leukocyte-poor PRP) and activation methods, including calcium chloride or thrombin use versus in vivo activation after injection, may further influence therapeutic effects [10]-[12]. This variability in preparation parameters remains a major source of heterogeneity in clinical outcomes and underscores the need for standardized PRP protocols in hair restoration therapy [8] (See Figure 1).

Figure 1. Schematic illustration of platelet-rich plasma (PRP) preparation process. Venous blood is collected into anticoagulant-containing tubes, gently mixed, and subjected to centrifugation to separate components into erythrocytes (bottom layer), platelet-poor plasma (PPP, upper layer), and the intermediate platelet-rich fraction for therapeutic use.

Define The therapeutic effects of PRP in hair restoration are primarily attributed to the release of bioactive growth factors that modulate hair follicle stem cells and the surrounding microenvironment. Upon activation (e.g., by thrombin or calcium chloride), platelets release α-granules containing over 30 growth factors, cytokines, and chemokines that regulate cell proliferation, differentiation, angiogenesis, and inflammation, all critical processes for hair follicle regeneration [12][13]. These biological effects are supported by clinical studies demonstrating significant increases in hair density and thickness following PRP treatment [11].

Key growth factors in PRP include platelet-derived growth factor (PDGF), which stimulates hair follicle stem cell proliferation and matrix cell growth; transforming growth factor-β (TGF-β), which promotes follicular angiogenesis and extracellular matrix synthesis; vascular endothelial growth factor (VEGF), which enhances scalp microcirculation and delivers nutrients to hair follicles; and insulin-like growth factor (IGF), which prolongs the anagen phase and prevents follicular miniaturization [8][14][15]. Growth factors released from activated platelets stimulate dermal papilla cells and promote angiogenesis [16]. These growth factors act on dermal papilla cells (DPCs), which serve as the regulatory center of hair follicle growth, by activating signaling pathways (e.g., PI3K/Akt, MAPK) that promote DPC survival and function [13][17].

In addition to direct effects on hair follicles, PRP modulates the inflammatory microenvironment in conditions like AA, where autoimmune-mediated inflammation contributes to follicular damage. Studies have shown that PRP reduces the expression of pro-inflammatory cytokines (e.g., IFN-γ, TNF-α) and increases anti-inflammatory cytokines (e.g., IL-10) in lesional scalp tissue, thereby suppressing autoimmune activity and promoting follicular recovery [18][19]. For AGA, PRP counteracts the effects of dihydrotestosterone (DHT)—the primary driver of follicular miniaturization—by upregulating the expression of anti-androgenic genes and downregulating genes involved in DHT signaling [9][10].

The route of PRP administration also influences its mechanism of action. Intralesional or intradermal injection delivers PRP directly to the perifollicular region, ensuring maximal concentration of growth factors at the target site [20][21]. Topical PRP application, when combined with transepidermal delivery systems like microneedling or fractional carbon dioxide laser, enhances penetration of bioactive components through the stratum corneum, improving their bioavailability to hair follicles [3][22]. Furthermore, PRP has been shown to enhance the survival of transplanted hair follicles in hair restoration surgery by improving graft vascularization and reducing ischemia-reperfusion injury [23][24].

Key clinical studies evaluating platelet-rich plasma (PRP) therapy for different alopecia subtypes are summarized in Table 1.

Table 1. Key clinical studies evaluating PRP efficacy in alopecia subtypes.

To improve interpretability and reduce bias due to heterogeneity, findings were synthesized according to both alopecia subtype (androgenetic alopecia, alopecia areata, telogen effluvium) and treatment modality. PRP monotherapy, combination therapies (e.g., PRP with minoxidil or microneedling), and peri-transplant applications were considered and interpreted separately to avoid overgeneralization of efficacy outcomes.

Of the 52 included studies, the majority focused on androgenetic alopecia (n = 33), followed by alopecia areata (n = 11), telogen effluvium (n = 2), and PRP use in hair transplantation settings (n = 3), while the remaining 3 studies included mixed or overlapping indications that were not classified into a single category. Several studies assessed PRP as monotherapy, while others evaluated combination approaches (e.g., PRP with minoxidil or microneedling) or peri-transplant applications. These categories were analyzed within their respective subgroups to ensure a more precise interpretation of efficacy outcomes.

Unless otherwise specified, efficacy statements refer to PRP monotherapy, while combination and adjunctive applications are discussed separately. Therapeutic outcomes are presented below according to alopecia subtype, with consideration of differences between monotherapy, combination therapy, and adjunctive applications.

3.3.1. Alopecia Areata (AA)

Alopecia areata is an autoimmune disorder characterized by patchy hair loss on the scalp or other body areas, caused by T-cell-mediated destruction of anagen hair follicles. Increasing clinical evidence supports the use of PRP in AA, particularly in patients with recalcitrant or corticosteroid-resistant disease. In a randomized controlled trial (RCT), Abedini et al. (2025) [25] evaluated combination therapy with diphenylcyclopropenone (DPCP) and PRP, reporting superior hair regrowth rates (78.6%) compared to the DPCP monotherapy group (53.3%), with a longer duration of response, while a placebo-controlled split-scalp study by Hegde et al. (2020) [26] demonstrated the efficacy of PRP monotherapy in AA.

In alopecia areata, PRP has been evaluated both as monotherapy and in combination with established treatments such as intralesional corticosteroids or diphenylcyclopropenone (DPCP), with combination approaches generally demonstrating enhanced or more sustained responses [25][27][28].

Several studies have compared PRP with intralesional triamcinolone acetonide (TAC)—the gold standard for AA treatment. Kapoor et al. (2020) [27] conducted a comparative study of intralesional TAC versus intralesional PRP in 60 AA patients, reporting similar hair regrowth rates (66.7% vs. 63.3%) but fewer side effects in the PRP group. Similarly, Balakrishnan et al. (2020) [29] found no significant difference in therapeutic response between PRP and TAC, but noted that PRP was better tolerated in patients with long-standing AA. Afsar Khan et al. (2022) [28] further confirmed these findings, reporting a 68% response rate in PRP-treated patients versus 72% in TAC-treated patients, with PRP associated with minimal local adverse effects. Across controlled studies, response rates generally ranged between 60% and 80%, suggesting that PRP may offer clinically meaningful benefit in AA [27]-[29]. The variability in outcomes likely reflects differences in disease severity, PRP preparation methods, and treatment intervals rather than inconsistency in biological effect.

PRP has also shown efficacy in recalcitrant AA, where conventional therapies often fail. Aydogan (2025) [20] evaluated intralesional PRP in 32 patients with recalcitrant AA, finding that 56.7% achieved partial to complete hair regrowth after 6 months of treatment, with sustained regrowth at 12-month follow-up. Abd El-Magid et al. (2023) [30] similarly reported that combination therapy with DPCP and PRP was effective in 73.3% of patients with severe or recalcitrant AA, compared to 46.7% in the DPCP monotherapy group. Patient characteristics may also affect PRP efficacy in AA; Abadjieva et al. (2024) [19] found that PRP was equally effective in AA patients with normal and elevated thyroid antibody levels, suggesting that thyroid autoimmunity does not impair PRP efficacy.

3.3.2. Androgenetic Alopecia (AGA)

Most evidence in AGA pertains to PRP monotherapy or PRP combined with topical or oral minoxidil, while a smaller subset of studies evaluates PRP as an adjunct in hair transplantation settings. These modalities demonstrate differing magnitudes of effect and are therefore interpreted separately.

Androgenetic alopecia, the most common cause of chronic hair loss, is characterized by progressive follicular miniaturization driven by dihydrotestosterone (DHT), resulting in patterned thinning and gradual reduction in hair density. PRP has been extensively investigated in AGA and is supported by a growing body of controlled clinical evidence, both as a standalone treatment and as part of combination regimens.

Across randomized controlled trials in male AGA [31]-[33], PRP has consistently been associated with improvements in hair density and shaft thickness compared with placebo. Dicle et al. (2020) [34] conducted a randomized placebo-controlled crossover study in 30 male AGA patients and observed a substantial increase in hair density following PRP treatment, with gains markedly exceeding those seen during the placebo phase (23.4 vs. 5.2 hairs/cm²), and 73.3% of patients reporting subjective improvement. In female AGA, Dubin et al. (2020) [2] similarly reported meaningful gains in hair density in the PRP group compared with placebo (18.7 vs. 4.3 hairs/cm²), with 66.7% of patients achieving partial to complete hair regrowth. Retrospective analyses have also reported favorable clinical outcomes with PRP [35]. Collectively, randomized evidence suggests that PRP-associated increases in hair density typically range between 18 and 32 hairs/cm² [2][34], with clinical response rates exceeding 60% across multiple controlled studies [31]-[34]. Reported effect sizes varied across studies due to differences in measurement techniques and study design. The observed variability in outcomes likely reflects differences in disease stage, platelet concentration, injection protocols, and follow-up duration rather than true inconsistency in biological effect.

Comparative studies with conventional therapies suggest that PRP performs at least comparably to topical minoxidil and may confer additional benefit when incorporated into combination regimens [36]-[38]. In a randomized controlled pilot trial in women with AGA, PRP demonstrated significant improvements in hair density compared with baseline, with outcomes comparable to topical minoxidil foam [39]. Ray et al. (2021) [40] evaluated 5% minoxidil monotherapy versus minoxidil combined with PRP in 100 male AGA patients and reported significantly greater increases in hair density and overall response rates in the combination group (32.6 vs. 18.4 hairs/cm²; 82% vs. 64%). Combination therapy with PRP and topical minoxidil may exert synergistic effects on follicular stimulation [41], supporting its role as an adjunct rather than merely an alternative therapy. Treatment-related variables appear to influence PRP efficacy in AGA, including preparation methods, platelet concentration, and administration frequency; Budania et al. (2023) [8] demonstrated that PRP prepared using a double-spin method, which yields a higher platelet concentration, resulted in greater increases in hair density compared with a single-spin technique. Adjunctive use of PRP during hair transplantation has likewise been associated with improved graft survival and enhanced postoperative hair growth quality [5][23].

3.3.3. Telogen Effluvium (TE) and Other Hair Loss Subtypes

Telogen effluvium is a transient form of hair loss characterized by excessive shedding of telogen hair follicles, triggered by factors such as pregnancy, childbirth, stress, nutritional deficiencies, or medication use. PRP has been studied as a therapeutic option for chronic TE, where spontaneous recovery is delayed. El-Dawla et al. (2022) [42] conducted an RCT in 30 female patients with chronic TE, finding that PRP significantly reduced hair shedding (mean reduction of 42.3%) and increased hair density (mean increase of 16.7 hairs/cm²) compared to placebo, with 70% of patients achieving a significant reduction in shedding. Evidence in telogen effluvium is limited and primarily reflects PRP monotherapy, with minimal data available on combination or adjunctive treatment approaches [15][42].

PRP has also shown efficacy in less common hair loss subtypes. Rossi et al. (2026) [43] evaluated PRP in 25 breast cancer survivors with endocrine-induced alopecia and persistent chemotherapy-induced alopecia (CIA), finding that PRP significantly increased hair density (mean increase of 19.4 hairs/cm²) and reduced hair thinning, with 68% of patients reporting subjective improvement. This is particularly significant, as CIA and endocrine-induced alopecia are often resistant to conventional therapies. Khan et al. (2025) [4] conducted a prospective clinical trial evaluating PRP in 50 patients with various types of hair loss (AGA, AA, TE), finding that PRP was effective in 72% of patients overall.

Overall, while PRP demonstrates promising efficacy across multiple alopecia subtypes, the magnitude of therapeutic benefit appears to vary by treatment modality, with combination therapies and peri-transplant applications generally showing greater or more consistent improvements compared to PRP monotherapy [40][41][44].

One of the key advantages of PRP is its excellent safety profile, attributed to its autologous nature, which eliminates the risk of allergic reactions, immune rejection, or transmission of infectious diseases [45][46]. Most adverse events associated with PRP are mild, transient, and localized to the treatment site, resolving within 24 - 72 hours without intervention.

The most common adverse events reported in clinical studies include injection-site pain, tenderness, erythema, edema, and pruritus. Muhammad et al. (2022) [45] reported injection-site pain in 32% of patients treated with PRP for AGA, but noted that the pain was mild (visual analog scale score ≤ 3/10) and resolved within 24 hours. Rare adverse events include infection, hematoma, and transient hair shedding. Infection is extremely rare (occurring in less than 1% of patients), typically associated with improper sterile technique, while hematoma formation is more common in patients on anticoagulant medications (Khan et al., 2025; Dubin et al., 2020) [2][4]. Transient hair shedding, occurring 2 - 4 weeks after treatment, has been reported in 5% - 10% of patients, resolving spontaneously within 4 - 6 weeks [47][48].

No systemic adverse events have been consistently reported in clinical studies, confirming PRP’s safety for systemic use. Long-term safety data for PRP is limited but promising; follow-up studies of up to 12 months have shown no late adverse events (e.g., scarring, hypopigmentation, follicular damage) in PRP-treated patients [25][49].

The Patient satisfaction and quality of life (QoL) are critical outcomes in hair restoration, as hair loss has significant psychological and social impacts. Several studies have evaluated patient satisfaction with PRP treatment, consistently reporting high satisfaction rates and quality of life improvement following PRP therapy [50]. Meyers et al. (2023) [51] evaluated QoL in 40 patients treated with PRP for hair loss, finding that PRP significantly improved QoL scores (mean increase of 28.6 points on the Dermatology Life Quality Index), with 87.5% of patients reporting improved self-esteem and confidence.

In AGA patients, Hetz et al. (2022) [46] reported that 85% of patients were satisfied or very satisfied with PRP treatment, citing improved hair thickness, reduced hair loss, and a more natural appearance compared to conventional therapies. AA patients also report high satisfaction with PRP; Abedini et al. (2025) [25] found that 82.1% of AA patients treated with PRP plus DPCP were satisfied with treatment outcomes, compared to 57.1% in the DPCP monotherapy group. Patient satisfaction with PRP is influenced by treatment efficacy, safety, and convenience, with its minimally invasive nature and lack of systemic side effects contributing to favorable outcomes [3][14].