Injections of platelet-rich plasma for androgenic alopecia: A systematic review

The aim of this literature review was to evaluate the effects of PRP injections into the scalp of patients with androgenic alopecia. A literature review was conducted using the Pubmed and Google Scholar databases with the search terms "platelet-rich plasma" or "platelet-rich fibrin" and "hair" or "alopecia" or "androgenic alopecia". The publications included had to clinically assess the efficacy of PRP injections in patients with androgenic alopecia. Out of the 32 publications retrieved, 14 publications were included, of which 3 randomized, 4 prospective controlled, 4 prospective uncontrolled and 3 retrospective studies. Seven out of 9 studies reported a significant increase of hair density ranging between 12.3 and 45.9 hairs/cm², (i.e. 19-31% hairs/cm²). Four studies assessed hair loss with the traction test and found a negative result after treatment in more than 95% of patients. Regarding hair thickness, 1 study reported an increase in hair diameter of 46.4% and 1 reported an increase of 106.4% of the "Hair mass index". Overall, the use of PRP injections in patients with androgenic alopecia seems effective with respect to promoting lost hair regrowth, decreasing hair loss and increasing hair thickness. The effects appear to be progressive from the first injection session, to peak after 3 to 5 sessions and to be attenuated in the absence of further injections. No major adverse effect was reported in the 14 clinical studies.