PRP that stands for platelet-rich plasma has been emerging for the past many years as a new treatment option in cosmetic surgery, dermatology and aesthetic medicine. PRP started in hematology around 1970s and later made its way in maxillofacial surgery to achieve hemostasis it was not until 2006 that PRP made its way in dermatology and cosmetic medicine for tissue rejuvenation. (Alves and Grimalt, 2018)

Being a non-invasive injection-based treatment, it is gaining popularity not only with the patients but also with the physicians and surgeons who are offering it. Platelets as we all know are rich in growth factors and therefore work on the “Golden anchorage” of the hair follicle to promote hair growth and nourishment. (Garg and Manchanda, 2017).

Pathogenesis of alopecia

Alopecia can be classified into two broad categories—non-cicatricial and cicatricial alopecia. The causes of non-cicatricial alopecias include androgenetic alopecia, telogen effluvium, alopecia areata, trichotillomania, anagen effluvium etc. While cicatricial alopecia may include lichen planopilaris, frontal fibrosing alopecia, folliculitis decalvans, cutaneous discoid lupus erythematosus etc.

The most common type of alopecia is the androgenetic alopecia (AGA) that can affect as much as 80% population to some extent. AGA most commonly occurs due to the miniaturization of the follicular units within hair follicle. The progressive reduction of diameter, pigmentation and length of hair is the hallmark signature of AGA. 

Platelet rich plasma classification

(Dohan Ehrenfest et al., 2014) proposed classification of platelet-rich plasma into four main categories according to the cell content and structure of proteins in it.

  1. Pure PRP (P-PRP) is leucocyte-poor platelet rich plasma-preparations which are leucocyte poor and have a low-density fibrin network on activation.
  2. Leucocyte- and platelet rich plasma (L-PRP) has leucocytes and upon activation form a low-density fibrin network;
  3. Pure platelet-rich fibrin (P-PRF) or leucocyte-poor platelet-rich fibrin-preparations which are leucocyte poor and with a fibrin network which is high-density. P-PRP is mixed with an activator and a specific separator gel is used;
  4. Leucocyte- and PRF (L-PRF) or second-generation PRP products—preparations with leucocytes and a high-density fibrin network. For the formulation of L-PRF, blood is centrifuged immediately after collection without any anticoagulant, thrombin or CaCl2.

In 2016, a new classification was proposed; the DEPA classification (Dose, Efficiency, Purity, Activation) that focuses on the quantity of platelets obtained by the PRP kits as well as on product purity and on platelet activation prior to injection. (Magalon et al., 2016)

Evidence in Alopecia

The most prominent role of PRP is found in androgenetic alopecia.

  1. (Singhal et al., 2015) showed that by the end of 3 months, all ten androgenetic alopecia patients treated with PRP had good hair growth with reduction in number of pulled out hair by average of 65%. New hair growth was observed in 6 patients as early as 7 days and in 4 patients within 15 days.
  2. (Uebel et al., 2006) observed significant improvement in hair density and stimulation of growth on pre-treatment of follicular units with platelet plasma growth factors before their implantation.
  3. (Gentile et al., 2015) showed in a RCT that at the end of the 3 treatment cycles, the patients presented significant clinical improvement in the mean number of hairs and a mean increase in total hair density compared with baseline values.

A meta-analysis showed increased number of hairs in the treated areas with minimal morbidity, but a lack of scientific evidence on this treatment modality. (Giordano et al., 2018)

Mechanism of action of PRP

PRP increases the expression of type I collagen, MMP-1 and mRNA in human dermal fibroblasts. It has also been shown to increase the proliferation of human adipose-derived stem cells. Increase in platelet derived growth factor (PDGF) is crucial as it signals the epidermis-follicle interaction with the dermal mesenchymal cells for the growth of the later and hence the hair follicle. (Kim et al., 2011; Maria-Angeliki et al., 2015)

PRP also contains vascular endothelial growth factors which are major mediators in hair follicle growth and cycling as they promote revascularization of the hair follicle. Basic fibroblast growth factor (bFGF) promotes the proliferation of cells of papilla, and therefore, plays a key role in hair shaft elongation. (Yano, Brown and Detmar, 2001; Gentile et al., 2015)

PRP also increases the proliferation of human dermal papilla cells by increasing the phosphorylation of extracellular signal-regulated kinases. (Li et al., 2012)

Complications of PRP

Absolute contraindications:(‘Section VIII Platelet Rich Plasma (PRP) Guidelines CHAPTER 1 HISTORICAL PERSPECTIVE’, no date)

  1. Platelet dysfunction syndrome;
  2. Critical thrombocytopenia;
  3. Hemodynamic instability;
  4. Septicaemia;
  5. Local infection at the site;
  6. Patient unwilling to sign consent.
  7. Relative contraindications:
    • Consistent use of NSAIDs within 48 hours of procedure;
    • Corticosteroid injection at treatment site within 1 month;
    • Systemic use of corticosteroids within 2 weeks;
    • Use of tobacco;
    • Recent fever/illness;
    • Cancer-especially hematopoietic or bone;
    • Haemoglobin<10 g/dL;
    • Platelet count <105/µL.

International Guidelines

European Dermatology Forum (EDF) 2017 guidelines for treatment of androgenetic alopecia suggested insufficient evidence to recommend for or against platelet-rich plasma (PRP) for androgenetic alopecia.


Although being a safe procedure it does has some complications that may happen rarely.

  • pain in the injected area
  • infection
  • allergic reaction-urticarial rash
  • headache
  • heaviness of head
  • swelling
  • redness
  • temporary skin discoloration
  • bruising


Although PRP is a new and promising arena in hair growth and rejuvenation treatment it is still unknown whether it has long lasting effects or preventive benefits. We need more studies and literature on this particular topic. There is also a dire need of international guidelines on use of PRP in different diseases of hair regrowth. One thing that can be said for sure is that it won’t be able to replace hair transplant in near future. However, it can still be a great tool in treating hair diseases.


  1. Alves, R. and Grimalt, R. (2018) ‘A Review of Platelet-Rich Plasma: History, Biology, Mechanism of Action, and Classification.’, Skin appendage disorders. Karger Publishers, 4(1), pp. 18–24. doi: 10.1159/000477353.
  2. Dohan Ehrenfest, D. M. et al. (2014) ‘Classification of platelet concentrates (Platelet-Rich Plasma-PRP, Platelet-Rich Fibrin-PRF) for topical and infiltrative use in orthopedic and sports medicine: current consensus, clinical implications and perspectives.’, Muscles, ligaments and tendons journal. CIC Edizioni Internazionali, 4(1), pp. 3–9. Available at: (Accessed: 15 July 2018).
  3. Garg, S. and Manchanda, S. (2017) ‘Platelet-rich plasma-an “Elixir” for treatment of alopecia: personal experience on 117 patients with review of literature.’, Stem cell investigation. AME Publications, 4, p. 64. doi: 10.21037/sci.2017.06.07.
  4. Gentile, P. et al. (2015) ‘The Effect of Platelet-Rich Plasma in Hair Regrowth: A Randomized Placebo-Controlled Trial’, STEM CELLS Translational Medicine, 4(11), pp. 1317–1323. doi: 10.5966/sctm.2015-0107.
  5. Giordano, S. et al. (2018) ‘A Meta-analysis On Evidence Of Platelet-rich Plasma for Androgenetic Alopecia.’, International journal of trichology. Medknow Publications and Media Pvt. Ltd., 10(1), pp. 1–10. doi: 10.4103/ijt.ijt_74_16.
  6. Kim, D. H. et al. (2011) ‘Can Platelet-rich Plasma Be Used for Skin Rejuvenation? Evaluation of Effects of Platelet-rich Plasma on Human Dermal Fibroblast’, Annals of Dermatology, 23(4), p. 424. doi: 10.5021/ad.2011.23.4.424.
  7. Li, Z. J. et al. (2012) ‘Autologous Platelet-Rich Plasma: A Potential Therapeutic Tool for Promoting Hair Growth’, Dermatologic Surgery, 38(7pt1), pp. 1040–1046. doi: 10.1111/j.1524-4725.2012.02394.x.
  8. Magalon, J. et al. (2016) ‘DEPA classification: a proposal for standardising PRP use and a retrospective application of available devices’, BMJ Open Sport & Exercise Medicine, 2(1), p. e000060. doi: 10.1136/bmjsem-2015-000060.
  9. Maria-Angeliki, G. et al. (2015) ‘Platelet-rich plasma as a potential treatment for noncicatricial alopecias’, International Journal of Trichology, 7(2), p. 54. doi: 10.4103/0974-7753.160098.
  10. ‘Section VIII Platelet Rich Plasma (PRP) Guidelines CHAPTER 1 HISTORICAL PERSPECTIVE’ (no date). Available at: (Accessed: 15 July 2018).
  11. Singhal, P. et al. (2015) ‘Efficacy of platelet-rich plasma in treatment of androgenic alopecia’, Asian Journal of Transfusion Science, 9(2), p. 159. doi: 10.4103/0973-6247.162713.
  12. Uebel, C. O. et al. (2006) ‘The Role of Platelet Plasma Growth Factors in Male Pattern Baldness Surgery’, Plastic and Reconstructive Surgery, 118(6), pp. 1458–1466. doi: 10.1097/01.prs.0000239560.29172.33.
  13. Yano, K., Brown, L. F. and Detmar, M. (2001) ‘Control of hair growth and follicle size by VEGF-mediated angiogenesis’, Journal of Clinical Investigation, 107(4), pp. 409–417. doi: 10.1172/JCI11317.