O04 Pharmacological efficacy of low-dose oral minoxidil–finasteride combination for hair growth and stability in male androgenetic alopecia: a 12-month retrospective service evaluation

Abstract Androgenetic alopecia (AA) is characterized by progressive miniaturization of scalp follicles mediated by dihydrotestosterone. Conventional treatments include oral finasteride (a type II 5α-reductase inhibitor) and topical minoxidil, but topical regimens can be limited by application burden and local irritation. Low-dose oral minoxidil (2.5 mg) augments follicular blood flow and anagen prolongation, yet evidence on combining it with oral finasteride (1 mg) over the long term remains sparse. A once-daily coformulation may promote convenience and adherence. The aim of this study was to evaluate the 12-month effectiveness of a daily oral minoxidil–finasteride regimen in adult men with AA, focusing on (i) hair density changes across Norwood severities, (ii) effect sizes for different baseline categories, and (iii) inter-rater reliability of visual hair-loss scoring. A retrospective cohort of 502 men (age ≥ 18 years, Norwood 2–7) was identified from a digital health service’s records (January 2020 to December 2023). All received finasteride 1 mg per day plus minoxidil 2.5 mg per day. Standardized scalp images at baseline and 12 months were graded using a seven-point scale (from −3 = significant loss; to 0 = stable and no loss; to +3 = significant growth). The primary endpoint (mean seven-point change) was compared with zero using a one-sample t-test. Effect sizes (Cohen’s d, Hedge’s g) were calculated, and inter-rater reliability (Cohen’s κ) was assessed for baseline Norwood classifications and seven-point scores. Statistical clinical significance was set at P < 0.05. Among 502 men (mean age 35.5 years, SD 12.1), 92.4% (464 of 502) were stable or improved at 12 months, with 57.4% (288 of 502) showing overt regrowth. The inverse-variance weighted mean seven-point change was 0.58 (95% confidence interval 0.51–0.65, P < 0.001), indicating a statistically significant overall increase in hair density. Norwood 2–3 demonstrated moderate effect sizes (d ≈ 0.27–0.74), while Norwood 5–6 ranged from d ≈ 0.88 to d ≈ 1.11 (P < 0.001). Despite smaller sample sizes in Norwood 6 and 7, both groups recorded 100% stable or improved outcomes, with half to two-thirds demonstrating hair regrowth. Inter-rater reliability for baseline Norwood staging was κ = 0.33 (fair agreement), and seven-point changes κ = 0.20 (slight agreement), reflecting subjective variability in photo-based assessments. Daily administration of low-dose oral minoxidil and finasteride yielded robust, statistically significant improvements in men with AA (> 92.4%), including advanced stages. Effect sizes ranged from moderate in early hair loss to large in severe categories, suggesting a broad therapeutic window. Nonetheless, modest κ-values reinforce the necessity for objective imaging protocols or artificial intelligence-driven methods in future research. Prospective, controlled trials incorporating explicit safety monitoring and patient-reported outcomes are warranted to optimize dosing and validate long-term tolerability.