Minimally Invasive Non-Surgical Therapies for Androgenetic Alopecia: A Narrative Review of Clinical Evidence for Regenerative and Locally Acting Antiandrogen Treatments

Background: Androgenetic alopecia (AGA) is the most prevalent form of non-scarring alopecia, affecting up to 80% of men and 50% of women over a lifetime. Despite the established efficacy of oral finasteride and topical minoxidil, limitations including systemic adverse effects, the requirement for indefinite treatment to maintain benefit, and suboptimal long-term patient compliance have stimulated growing clinical interest in minimally invasive, locally delivered therapeutic approaches targeting the follicular microenvironment directly. Objective: To evaluate and compare the available clinical evidence for six minimally invasive non-surgical interventions in AGA: platelet-rich plasma (PRP), microneedling, mesotherapy, intradermal antiandrogen therapy (dutasteride and finasteride), topical finasteride, and polynucleotide/polydeoxyribonucleotide (PN/PDRN) injections. Methods: A systematic search of PubMed and Scopus was conducted for the period January 2000 to March 2026 using pre-defined Boolean search strings. Studies were eligible if they enrolled adults with clinically or trichoscopically confirmed AGA, evaluated one of the six specified interventions, and reported quantitative hair outcome measures. Due to substantial heterogeneity in study design, intervention protocols, and outcome reporting methods, a formal meta-analysis was not conducted; findings are presented as a structured narrative synthesis following PRISMA 2020 reporting guidance where applicable to a single-author narrative synthesis. Results: Forty-seven studies fulfilled the pre-specified eligibility criteria, comprising 18 randomized controlled trials (RCTs), 22 prospective or controlled cohort studies, and 7 retrospective analyses. The most consistent evidence was identified for PRP, supported by multiple RCTs with objective trichoscopic endpoints, and for topical finasteride, which demonstrated non-inferiority to oral finasteride in a phase III trial with substantially reduced systemic drug absorption. Microneedling in combination with topical minoxidil demonstrated significantly superior outcomes over monotherapy in the largest available RCT. Intradermal dutasteride showed promising follicular efficacy with reduced systemic dihydrotestosterone (DHT) suppression relative to equivalent oral dosing. Mesotherapy and PN/PDRN therapies demonstrated directionally positive results, limited by small sample sizes, heterogeneous intervention protocols, and the absence of adequately powered controlled trials. Conclusion: PRP, microneedling combined with topical minoxidil, and topical finasteride represent evidence-informed treatment options within the contemporary management of AGA. Intradermal dutasteride warrants evaluation in larger, prospectively registered controlled trials. Mesotherapy and PN/PDRN injections require protocol standardisation and rigorous placebo-controlled evidence before definitive clinical recommendations can be issued. The conclusions of this review are constrained by protocol heterogeneity across included studies and the absence of formal risk-of-bias assessment.