FormalPara Key Summary Points

Why carry out this study?

There is a paucity of literature on caring for hair in transgender individuals

This study summarizes current literature to provide dermatologists with current evidence regarding hair changes in transgender patients on hormonal therapy and the various treatments that can utilized to improve their hair

What was learned from this study?

Transgender men and women undergo numerous hair changes, both desired and undesired

Dermatologists can utilize numerous tools in their armamentarium that can help patients to improve their hair growth and help remove unwanted hair

Introduction

Characterized by distinct colors, textures, and styles, hair is intrinsically linked to personality and identity. For transgender and gender non-conforming patients, the appearance of hair is critical to refining society’s perception in their affirmed gender; this, in turn, affords them a greater sense of confidence and safety.

The transgender population includes those with an array of identities in which the gender identity and/or expression differs from the sex the person was assigned at birth. Other patients may identify as non-binary or genderqueer, describing a gender identity and/or expression that falls outside the typical binary categories of male and female [1]. For the purposes of this article, the term transgender women refers to those assigned male at birth but who identify on the female end of the gender spectrum; transgender men refers to those assigned female at birth but who identify on the male end of the spectrum.

Gender dysphoria—the distress that arises from the incongruity between the gender that was assigned to an individual at birth and the gender with which the individual identifies and expresses—has various treatment options, which depend on the individual patient’s goals. Hormonal therapy, gender-affirming procedures, and surgery can improve the alignment of patients’ physical characteristics with the gender that they choose to express.

Despite the myriad therapeutic options available to transgender patients, individual interventions may fall short of achieving the desired effect on their hair, especially regarding masculinizing or feminizing hormonal therapy. Hormonal therapy alters hair growth; however, supplemental treatments are frequently required to achieve the hair growth patterns that patients desire.

As altering patterns of hair growth continue to play an integral part in the affirmation of gender in patients with gender dysphoria, the relevance of dermatologic techniques must be emphasized. These interventions can be incorporated into masculinizing and feminizing therapy and may be increasingly important as the barriers to healthcare faced by transgender patients are recognized and addressed [2]. Therefore, this systematic review of current literature serves to characterize hair sequelae in response to the gender-affirming process and guide dermatologists in caring for the hair of their transgender patients. Given the relative paucity of literature on the topic, information derived from the systematic review was supplemented with the authors’ own experience and recommendations.

Methods

The report was written in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statements [3]. In April 2021, a comprehensive search of EMBASE, MEDLINE, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews from each database’s inception through April 21, 2021, was carried out. Search terms included “transgender” and “hair.” Titles and abstracts were reviewed, and if deemed eligible, full-text articles were assessed. Articles were eligible for inclusion if they included data relating to hair changes or treatment in transgender individuals. Exclusion criteria included abstracts and review articles. No date or language restrictions were applied. The titles and abstracts of all articles were initially screened for potential inclusion. The full text was assessed if the title and abstract did not include enough information for exclusion and inclusion criteria to be applied. The full text of the remaining articles was then evaluated for inclusion.

This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by any of the authors.

Results

The database search identified 246 studies (149 from EMBASE, 78 from MEDLINE, 9 from Cochrane Central Register of Controlled Trials, and 0 from Cochrane Database of Systematic Reviews) (Fig. 1). Sixty-one duplicates were removed. Titles and abstracts of the remaining 185 articles were reviewed, resulting in the exclusion of 107 studies (47 abstracts and 60 review articles). The remaining 78 articles were reviewed in their entirety, resulting in the exclusion of an additional 42 studies that did not evaluate hair changes or treatment in transgender individuals. Thirty-five studies met the inclusion criteria [2, 4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37]. Broadly, 14 evaluated hair changes of patients on masculinizing and feminizing hormonal therapy [7, 9, 17,18,19, 21, 22, 26, 31,32,33,34,35,36], 4 articles related to insurance coverage of gender-affirming procedures [2, 12, 15, 20], 6 assessed patient’s quality of life and/or mental wellbeing [16, 23,24,25, 28, 29], 6 articles discussed hair treatments [6, 11, 13, 14, 27, 37], 3 assessed patient demand for minimally invasive gender-affirming procedures [8, 10, 30], and 2 assessed patient/physician understanding of gender-affirming procedures [4, 5]. Table 1 summarizes the study findings.

Fig. 1
figure 1

Search methodology and results

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Table 1 Summary of study findings
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Discussion

Effects of Hormonal Therapy on Hair

The individual’s goals of masculinizing and feminizing hormonal therapy vary widely. Some patients strive for maximal expression of feminine or masculine features; others seek a more androgynous presentation through minimizing preexisting masculine or feminine features. Most physical changes occur within 2 years of initiating hormone therapy, but the degree of changes and the time over which they occur is highly variable, depending on the dose, route, and type of medications used. Currently, there is no evidence to suggest that any method of treatment is more effective than another in producing desired physical changes; therefore, current guidelines suggest treatment be made in accordance with each patient’s specific goals and medical risk profile [38].

Feminizing Hormonal Therapy

A combination of estrogens and antiandrogens such as spironolactone and cyproterone are used to emphasize feminine features and minimize masculine features. Typically, estrogen has a greater effect on body hair than facial hair, though facial hair is reported to decrease in 28% [18] of adults and 71.4% of adolescents. Over the first year of feminizing hormonal therapy, the Ferrimen and Gallway (F&G) scores evaluating body hair growth decrease, even though patients typically continue to score above 7—the score considered indicative of hirsutism [36]. Hair diameter shows marked decrease during the initial 4 months of therapy before stabilizing [36]. Neither growth rate, nor density, nor diameter falls to the values typical of cis-gendered females with hormonal therapy alone [36].

When initiating feminizing hormonal therapy, transgender women with preexisting androgenic alopecia may experience varying degrees of hair regrowth. However, hormonal therapy alone has only been rarely reported to induce significant regrowth. Adenuga et al. [34] reported a case of a transgender woman with a history of androgenic alopecia, who had almost full regrowth of scalp hair after 6 months of starting estradiol 30 mg/60 ml twice daily and aldactone 100 mg daily. Stevenson et al. [31] report a transgender woman on estradiol 5 mg daily and spironolactone 150 mg daily who experienced both scalp hair regrowth as well as thickening of preexisting hair after 6 months of treatment. Other studies have reported little effect of feminizing hormonal therapy on scalp hair loss [17].

Masculinizing Hormonal Therapy

Masculinizing hormone therapy commonly relies on testosterone to inhibit estrogen and exert robust masculinizing effects. Testosterone has a significant effect on both facial hair growth and body hair growth, which has been reported in 53–100% and 34–100% of patients, respectively [9, 21, 35]. Increased facial hair growth can be noted within 1–6 months [7]. Within 1 year of initiating testosterone therapy, F&G scores increase by 6–21 points [22, 33, 36]. Upwards of 80% of patients treated with testosterone therapy achieve a score > 8, typically within the first 4 months [5]. Despite this, even after years of therapy, patients are unlikely to reach F&G scores typical of cis-gendered males, which Motosko et al. reported to be 10.5 (median; IQR, 7.25–12) [22, 33, 36]. Long-term treatment with testosterone results in scores ranging from 6 to 34 (median, 24), a finding independent of duration or type of testosterone therapy [32]. Over the first year after initiating testosterone therapy, hair growth rate, density, and diameter all increase progressively, but only hair diameter has been observed to reach values similar to cis-gendered males [36].

Masculinizing hormone therapy is associated with an increased risk of androgenic alopecia, which is often an undesirable side effect [17, 19]. This has been seen in up to 45% of patients [17, 19]. The risk of developing androgenic alopecia is likely dependent on patient age and genetic predisposition and less likely related to the duration or type of testosterone therapy [32]; it has been seen within 1–44 years of initiating testosterone therapy [19]. Treatment with 5-α-reductase inhibitors might prevent or reverse this side effect. Finasteride and dutasteride, 5-α-reductase inhibitors, may be uniquely valuable in treating hair loss in this population, as they decrease dihydrotestosterone—the primary androgen involved in the pathogenesis of androgenetic alopecia—without decreasing testosterone levels [39].

Dermatologic Interventions

One study by van de Grift et al. [29] showed that transgender men and women are greatly dissatisfied with their hair. Dermatologists are likely the most qualified to treat these patients and ultimately relieve some of the burden of gender dysphoria [5]. Numerous studies have shown a significant correlation with the amount and density of hair growth with more symptoms of gender dysphoria in transgender woman and less in transgender men [16, 23,24,25, 28, 29]. However, obtaining these procedures can be financially difficult, as only 16–40% insurances provide some degree of coverage for these procedures, most of which only permit coverage preoperatively for gender-affirming surgery [2, 12, 15, 20]. For those that wish to undergo these procedures, patients should be fully educated on treatment expectations, as many are unaware that procedures such as laser hair removal require multiple treatments [4]. Table 2 summarizes treatment recommendations.

Table 2 Summary of treatment recommendations
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Hair Growth

Anti-androgenic treatments of androgenic alopecia such as spironolactone, flutamide, bicalutamide, and cyproterone acetate should be prescribed with caution in transgender men on masculinizing therapy. Finasteride and dutasteride, 5-α-reductase inhibitors, may provide additional benefit. One study treated transgender men with androgenetic alopecia with oral finasteride 1 mg daily, and all patients improved one grade on the NH scale after an average of 5.5 months [37].

Other treatment options that are not anti-androgenic may have high clinical utility in this patient population. Topical 5% minoxidil does not interact with patients’ hormonal therapy and can be effectively utilized for improving hair density in the scalp and beard. Oral minoxidil is also an excellent option in these patients as it increases both scalp and body hair. Although there are no specific studies on oral minoxidil in this population, doses ranging from 1.25 to 5 mg can be considered [40]. From our personal experience on use of oral minoxidil, we recommend to start with 1.25 mg at night to be increased to 2.5 mg after 3 months if well tolerated.

Patients on feminizing hormonal therapy may also benefit from topical and oral minoxidil. However, doses should be much lower because of the risk of hypertrichosis. This possible side effect should be discussed in detail in this population as risks might exceed benefit. Frequency of hypertrichosis is dose dependent, with a reported prevalence < 10% with doses of 0.25 mg daily [40]. Therefore, we recommend treatment with 0.25 mg at night and follow-up every 3 months.

Hair transplantation techniques have been employed to masculinize and feminize patients’ hairlines, eyebrows, beards, chests, and pubic areas. Hair transplantation may be performed in concert with other facial feminization surgeries such as frontal bone reshaping, brow lifting, or hairline lowering [6, 14, 27].

Lastly, patients should be counseled on various nonmedical approaches to achieve ideal hair coverage. Areas of hair thinning may be camouflaged using tinted powders, fiber sprays, and creams or by careful hair coloring, styling, and tattooing. Wigs, hair pieces, and hair extensions can offer additional methods of coverage for areas of hair thinning.

Hair Removal

Hair removal may be desired for numerous reasons, and dermatologists should be aware of the various treatment options to help guide the patient in choosing the best treatment option. Photoepilation therapies such as laser or intense pulsed non-coherent light reduce and thin hair, promising semi-permanent results. Electrolysis has a higher rate of permanent hair reduction, but results tend to be variable and operator dependent. It requires treatment of individual hairs, requiring a substantial amount of time. Hair may be temporarily removed by using over-the-counter methods, such as shaving, depilatory creams, mechanical removal via tweezers, wax, and threading. Eflornithine 12.9% cream can slow facial growth, but its use is limited by costs and continuous twice daily application that is required for the effect to be sustained. All methods of epilation are unlikely to be affected by hormonal therapy; however, there is a theoretical risk of hyperpigmentation in patients taking estrogen that may be relevant with abrasive hair removal techniques [41].

The face is reported to be the highest priority among many transgender women regarding all gender-affirming procedures, higher than the chest or genitals [30]. The face is the most commonly reported site of excess hair in transgender women [13]. One study in the UK found 89% of transgender woman receiving laser hair removal had the procedure performed on the face and neck; 11% received treatment to the genital and groin area before gender-affirming surgery [8]. Another study found laser hair removal to be the most common facial procedure among transgender women [30]. Dermatologists most often perform laser hair removal services on transgender women who have not received gender-affirming surgery [10]. Nonetheless, dermatologists should be aware of the general process of gender-affirming bottom surgery as their role may greatly contribute to the process.

In patients undergoing vaginoplasty or phalloplasty, the skin harvested to construct the neovaginal cavity or neourethra respectively may require preoperative epilation. Consulting the treating surgeon is required to determine which areas will be harvested. Typically, the penile shaft or scrotum is used to line the vaginal cavity, and the radial forearm or anterolateral thigh is used to construct the neourethra. Removal of hair from skin grafted to construct the neophallus can be delayed until after surgery, but areas harvested for the neovagina and neourethra likely require hair removal prior to surgery to prevent postoperative intravaginal or intraurethral hair growth [11]. Postoperative hair within the vagina can be removed via manual plucking with forceps or use of depilatory creams. Whether electrolysis or laser hair removal is performed, surgery should be delayed until 3 months after the last hair removal treatment to ensure hair is permanently removed.

Conclusion

Increased hair growth with masculinizing therapy and decreased hair growth with feminizing therapy is well described. The best treatments for these patients and the role dermatologists can play in the gender-affirming process are still being established. Understanding the unique medical needs of the transgender population is increasingly important, especially as improved societal acceptance allows transgender men and women to live more easily in accordance with their affirmed gender identity and expression. Guidelines on caring for transgender patients can help dermatologists to fill in gaps in their knowledge [38]. Despite the existence of guidelines, dermatologists should be open in admitting inexperience with this patient population; respectful inquiry on medications and procedures with which physicians are unfamiliar is generally appreciated.

To be inclusive of the range of gender identities, intake forms should include write-in options on the patient’s chosen name, gender, and pronouns to incorporate the range of gender identities. Physicians and staff should incorporate the patient’s pronouns in every aspect of the practice, from phone calls to physician notes. Creating an inclusive environment for all gender identities is essential to improving transgender populations’ access to medical care and sets the foundation for an open physician-patient relationship.