{"title":"The safety and efficacy of finasteride for transgender men with androgenetic alopecia: a case series.","authors":"Yusuke Tominaga, Tomoko Kobayashi, Yuko Matsumoto, Tomoko Sako, Takatoshi Moriwake, Satoshi Horii, Takuya Sadahira, Satoshi Katayama, Takehiro Iwata, Shingo Nishimura, Kensuke Bekku, Kohei Edamura, Masami Watanabe, Motoo Araki","doi":"10.1186/s13256-025-05562-y","DOIUrl":null,"url":null,"abstract":"<p><strong>Background: </strong>Testosterone replacement therapy is commonly used in transgender men for masculinization. One of the most common adverse effects of testosterone replacement therapy is androgenetic alopecia. In Japan, finasteride is approved exclusively for cisgender men and is not indicated for transgender men. The aim of this clinical trial was to evaluate the safety and efficacy of finasteride in transgender men with androgenetic alopecia.</p><p><strong>Case presentation: </strong>This study included three transgender men (assigned female at birth, identifying as male), aged 44, 43, and 29 years. All participants were of Asian ethnicity. A clinical trial was conducted from October 2021 to December 2023. Transgender men aged 20-60 years who had not undergone hysterectomy, were undergoing testosterone replacement therapy, and who had been diagnosed with stage ≥ II androgenetic alopecia on the basis of the Norwood-Hamilton scale were recruited. The participants initiated treatment with 0.2 mg of finasteride per day for 3 months (phase 1). If no adverse events above grade 2 occurred, the dose was increased to 1.0 mg per day for an additional 3 months (phase 2). The primary endpoints were the incidence of treatment-related adverse events at 1 week, 1 month, and 3 months, as well as the rate of participants continuing treatment at 3 months. None of the patients experienced serious adverse events at 3 months, and all the patients extended their treatment to a total of 6 months. Improvements of at least one stage on the N-H scale were observed, but two participants experienced resumption of menstruation.</p><p><strong>Conclusion: </strong>Finasteride appears to be a safe and effective treatment for androgenetic alopecia in transgender men undergoing testosterone replacement therapy. However, its potential for reducing some of the effects of testosterone replacement therapy warrants further investigation.</p><p><strong>Trial registration: </strong>jRCT, jRCTs061210040, registered 7 October 2021, https://jrct.mhlw.go.jp/latest-detail/jRCTs061210040 .</p>","PeriodicalId":16236,"journal":{"name":"Journal of Medical Case Reports","volume":"19 1","pages":"468"},"PeriodicalIF":0.8000,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12482827/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Medical Case Reports","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1186/s13256-025-05562-y","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MEDICINE, GENERAL & INTERNAL","Score":null,"Total":0}
引用次数: 0
Abstract
Background: Testosterone replacement therapy is commonly used in transgender men for masculinization. One of the most common adverse effects of testosterone replacement therapy is androgenetic alopecia. In Japan, finasteride is approved exclusively for cisgender men and is not indicated for transgender men. The aim of this clinical trial was to evaluate the safety and efficacy of finasteride in transgender men with androgenetic alopecia.
Case presentation: This study included three transgender men (assigned female at birth, identifying as male), aged 44, 43, and 29 years. All participants were of Asian ethnicity. A clinical trial was conducted from October 2021 to December 2023. Transgender men aged 20-60 years who had not undergone hysterectomy, were undergoing testosterone replacement therapy, and who had been diagnosed with stage ≥ II androgenetic alopecia on the basis of the Norwood-Hamilton scale were recruited. The participants initiated treatment with 0.2 mg of finasteride per day for 3 months (phase 1). If no adverse events above grade 2 occurred, the dose was increased to 1.0 mg per day for an additional 3 months (phase 2). The primary endpoints were the incidence of treatment-related adverse events at 1 week, 1 month, and 3 months, as well as the rate of participants continuing treatment at 3 months. None of the patients experienced serious adverse events at 3 months, and all the patients extended their treatment to a total of 6 months. Improvements of at least one stage on the N-H scale were observed, but two participants experienced resumption of menstruation.
Conclusion: Finasteride appears to be a safe and effective treatment for androgenetic alopecia in transgender men undergoing testosterone replacement therapy. However, its potential for reducing some of the effects of testosterone replacement therapy warrants further investigation.
Trial registration: jRCT, jRCTs061210040, registered 7 October 2021, https://jrct.mhlw.go.jp/latest-detail/jRCTs061210040 .
期刊介绍：
JMCR is an open access, peer-reviewed online journal that will consider any original case report that expands the field of general medical knowledge. Reports should show one of the following: 1. Unreported or unusual side effects or adverse interactions involving medications 2. Unexpected or unusual presentations of a disease 3. New associations or variations in disease processes 4. Presentations, diagnoses and/or management of new and emerging diseases 5. An unexpected association between diseases or symptoms 6. An unexpected event in the course of observing or treating a patient 7. Findings that shed new light on the possible pathogenesis of a disease or an adverse effect
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