Female to Male Transition: Hormones, Surgery, and Health

Female-to-male transition, often abbreviated FTM or described as transmasculine, refers to the medical and social process through which a person assigned female at birth aligns their body and presentation with a male identity. The medical pathway typically centers on testosterone therapy, which drives most of the physical masculinization, and may include surgical procedures such as chest reconstruction or genital surgery. The changes are wide-ranging, affecting everything from voice pitch and body hair to blood chemistry and brain structure, and the timeline varies considerably from person to person.

What Testosterone Does in the First Year

Testosterone is the primary medical intervention in FTM transition, usually administered by injection, topical gel, or patch. One of the first changes most people notice is the cessation of menstrual periods. In a study of 74 trans men on intramuscular testosterone, about half stopped menstruating within the first two to six months of treatment, while roughly a third took longer than six months to reach full cessation.

Skin changes arrive early and peak around the six-month mark. Acne increases during the first year of testosterone therapy, peaking at about six months, though most people settle into no or mild acne after long-term treatment.¹ The skin itself becomes oilier and coarser. Body fat begins to redistribute away from the hips and thighs and toward the abdomen, following a more typically male pattern. Muscle mass gradually increases, though dramatic changes in strength take longer than many people expect.

Hair growth on the face and body begins within the first several months but takes years to fully develop. Only about one person in the studied cohort developed any noticeable scalp hair loss during the first year. Over the long term, though, roughly a third experienced mild frontotemporal recession and about a third had moderate to severe androgenetic alopecia, the same pattern-balding seen in cisgender men.²

How the Voice Deepens

Voice deepening is among the most desired and most-studied effects of testosterone therapy. The vocal folds thicken, and the speaking fundamental frequency drops. One longitudinal study found that average speaking pitch fell to about 125 Hz after twelve months of treatment, which is within the typical male reference range, though individual variation was large.³ Another study reported that after about 36 weeks, the pitch range of trans men overlapped with that of cisgender men, with the average drop at one year amounting to just under one octave.⁴

The picture is not uniformly rosy, however. One study of postmenopausal cisgender women receiving therapeutic testosterone found no significant change in median speaking frequency after a full year, despite serum testosterone levels well above endogenous female ranges.⁵ The discrepancy may relate to the age of the laryngeal tissues, the dose ranges used, or other physiological differences, but it is a reminder that testosterone alone does not guarantee a voice that reads as male to every listener. For some trans men, voice therapy can complement the hormonal changes by addressing pitch patterns, resonance, and intonation beyond what testosterone alters on its own.

Voice Therapy as a Complement to Hormones

Even after testosterone brings the fundamental frequency into a male range, some trans men find that habitual speech patterns, pitch variation, or intonation still cue listeners toward a feminine reading. Voice therapy targets those features directly. A group program at London’s Gender Identity Clinic found that participants achieved significant decreases in both reading and speaking pitch, along with reduced voice fatigue, improved confidence in public speaking, and a smaller gap between how their voice sounded and how they wanted it to sound.⁶

A 2025 randomized clinical trial specifically examined intensive intonation training for people seeking a more masculine-sounding voice. After training, naive listeners perceived participants’ voices as significantly more masculine, and participants themselves reported their voice felt more aligned with their gender identity. The training focused on shifting toward more downward intonation at the ends of sentences, reducing pitch variation, and slowing pitch changes, all of which are recognized male speech markers in many languages.⁷

Blood Cell Changes and Why They Need Monitoring

Testosterone stimulates red blood cell production. That is useful up to a point but can tip into erythrocytosis, a condition where hematocrit (the proportion of blood made up of red blood cells) climbs high enough to thicken the blood and raise the risk of clotting. In a large Dutch cohort of trans men using testosterone, hematocrit rose most steeply in the first year, climbing from a baseline of about 0.39 to 0.45 after twelve months. The probability of developing erythrocytosis continued to rise with time on treatment: roughly ten percent after one year and close to forty percent after ten years.⁸

Risk factors for high hematocrit include smoking, higher body mass index, older age at starting testosterone, pulmonary conditions, and the type of testosterone used. Long-acting undecanoate injections carried about three times the odds of elevated hematocrit compared with testosterone gel.⁹ A separate U.S. study of over 500 transmasculine patients found that about one in five experienced at least one episode of polycythemia, and that prior removal of the ovaries appeared to be an additional risk factor, a finding that had not been widely reported before.¹⁰ Regular blood draws to check hematocrit are a standard part of ongoing care for trans men on testosterone.

Cholesterol and Heart Health

Testosterone shifts the lipid profile in a direction that looks less favorable on paper. HDL cholesterol, sometimes called “good” cholesterol, drops consistently. One small study found a fall from about 52 to 40 mg/dL after a year of testosterone.¹¹ A larger study reported an average HDL decrease of about sixteen percent within the first two to ten months of starting treatment, along with a rise in triglycerides of roughly a quarter to a third over the study period.¹² Severe triglyceride elevations were rare, and LDL cholesterol remained below concerning thresholds in most people.

A systematic review that pooled multiple studies confirmed the pattern: exogenous testosterone was associated with modest increases in body mass index, hemoglobin and hematocrit, and LDL cholesterol, alongside decreases in HDL cholesterol. Blood pressure changes were small and inconsistent across studies, though occasional cases of hypertension that resolved after stopping testosterone have been documented.¹³ Whether these lipid shifts translate into higher rates of heart attack or stroke over a lifetime is still not clear. The data lean toward some increased cardiovascular risk, but long-term outcome studies are limited.

Bone Density

Testosterone on its own appears to keep bone density largely stable in adult trans men. A review of available evidence concluded that bone density remains mostly unchanged with pharmacologic testosterone, though androgens can influence bone indirectly by altering fat and lean mass.¹⁴ The situation is more nuanced for adolescents who first receive puberty blockers (GnRH agonists) before starting testosterone. Puberty blockers can temporarily decrease bone mineral density because they interrupt the normal estrogen-driven bone accrual that happens during puberty. Once testosterone is added, bone density tends to recover, though some studies suggest it may not fully return to pre-blocker levels at every skeletal site. A 2023 study in JAMA Pediatrics found that after long-term testosterone use following puberty suppression, z-scores at the lumbar spine and total hip were in the normal range and the authors concluded that the treatment sequence appeared safe for bone health.¹⁵

Fertility and Ovarian Function

A common concern is whether long-term testosterone use permanently impairs fertility. The evidence so far is more reassuring than many people expect. Testosterone suppresses ovulation and menstruation, but the ovaries are not destroyed. When researchers examined ovarian tissue from trans men who had been on testosterone for over a year and then underwent oophorectomy, the cortical follicle distribution looked surprisingly normal. Most follicles were still primordial, and cumulus-oocyte complexes retrieved from the ovarian medulla could be matured in the lab, with about a third reaching the stage needed for fertilization and most of those showing normal internal structure.¹⁶

That said, testosterone does suppress certain ovarian markers. Anti-Müllerian hormone (AMH), which reflects the pool of developing follicles, dropped significantly after about sixteen weeks of testosterone combined with a GnRH agonist in one study.¹⁷ Whether this translates into reduced fertility after stopping testosterone is still debated. Anecdotally and in case series, pregnancies after discontinuing testosterone are well documented, and clinical guidance now generally recommends discussing fertility preservation options before starting hormones, but does not treat testosterone as a permanent sterilizer.

There are almost no high-quality data on pregnancy complications specific to trans men. Vaginal birth is possible, and counseling should include all delivery options to optimize the individual’s experience and autonomy.

Vaginal Health and Cervical Screening

Testosterone suppresses estrogen, and one of the less-discussed consequences is its effect on vaginal tissue. The vaginal epithelium thins, glycogen levels drop, and the environment shifts in ways that resemble the postmenopausal vagina. Symptoms of vaginal atrophy, including dryness, irritation, and pain during penetration, are common among trans men on testosterone.¹⁸ A study that tracked vaginal changes before and after twelve weeks of testosterone found increased symptoms, higher vaginal pH, and worse vaginal maturation scores.¹⁹

The vaginal microbiome also shifts. In one study of 28 trans men on testosterone, only three had a Lactobacillus-dominated microbiome, which is the norm in premenopausal cisgender women. The majority had a diverse set of anaerobic bacteria, more similar to the postmenopausal pattern but still distinct from it.²⁰ Local estrogen therapy can sometimes be used to counteract vaginal atrophy without undermining the systemic effects of testosterone, though this is a conversation to have with a provider.

These tissue changes also create practical problems for cervical cancer screening. Trans men who still have a cervix need Pap smears, but the testosterone-induced atrophy makes it harder to collect adequate samples. In one study, the prevalence of unsatisfactory Pap results was over eight times higher among trans men compared with cisgender women, and even after adjusting for confounders, the odds remained about six times higher, with each additional year on testosterone further increasing the risk of an inadequate sample.²¹ Provider unfamiliarity with examining trans men and patient discomfort with the exam likely compound the problem. HPV self-swab options, where available, can help bridge this gap.

Chest Reconstruction

Top surgery, or gender-affirming mastectomy, is the most commonly performed surgical procedure in FTM transition. The goal is a flat, masculine-appearing chest contour. Techniques range from periareolar approaches (suitable for smaller chests) to double-incision mastectomy with nipple grafting (more common for larger chests). A major concern historically has been the loss of sensation in the nipple and surrounding chest skin, since the nerves are inevitably disrupted during surgery.

A 2024 study published in JAMA Network Open tested a technique called targeted nerve reinnervation, where surgeons deliberately reconnected cut sensory nerves during the mastectomy. After twelve months, patients who received this nerve repair had significantly better sensation across every modality tested, including light touch, vibration, temperature, and pinprick, both at the nipple-areolar complex and on the surrounding chest. Patients who had the reinnervation procedure also reported significantly better nipple sensation, chest light touch, and erogenous sensation compared to those who had standard surgery.²² This is a newer technique and not yet universally available, but it represents a meaningful advance for a procedure where sensation loss has long been accepted as an unfortunate tradeoff.

Genital Reconstruction

Genital surgeries for trans men are among the most complex procedures in reconstructive surgery, and there is no single approach that achieves everything a cisgender penis does. The two main options are metoidioplasty and phalloplasty, each with different strengths and limitations.

Metoidioplasty uses the testosterone-enlarged clitoris, which typically grows to a few centimeters on hormone therapy, to create a small phallus. A systematic review found that metoidioplasty cohorts averaged about six centimeters of penile length, with roughly three-quarters reporting the ability to urinate while standing. Compared with phalloplasty, metoidioplasty was significantly more likely to be completed in a single surgical stage, preserve erogenous sensation, and have a lower overall complication rate.²³ The tradeoff is size: the resulting phallus is typically too small for penetrative intercourse.

Phalloplasty constructs a full-sized phallus using a tissue flap, most commonly from the forearm (radial forearm flap) or the thigh (anterolateral thigh flap). The procedure allows for penetrative intercourse with the aid of an erectile implant placed in a later stage. Standing urination is possible but comes with higher complication rates: about a quarter to a third of patients in reviewed cohorts developed a urethral stricture or fistula regardless of flap type.²⁴ The radial forearm flap tends to produce better cosmetic results and thinner tissue, while the thigh flap avoids a visible scar on the arm but can be bulkier. Both approaches typically require multiple staged surgeries over a year or more. The decision between metoidioplasty and phalloplasty often comes down to personal priorities around size, donor-site scarring, surgical complexity, and which functions matter most to the individual.

Mental Health and Quality of Life

The mental health effects of testosterone therapy are consistently positive in the literature, though the strength of evidence is not yet what researchers would consider ironclad. A systematic review of 20 studies found that gender-affirming hormone therapy was associated with improvements in quality of life and decreases in depression and anxiety symptoms. The associations held across gender identities and age groups, though the authors noted that methodological limitations kept the overall strength of evidence low.²⁵ A prospective study focusing specifically on trans men found positive effects of testosterone on both sexual function and mood, including during the early months of treatment and continuing after surgical procedures.²⁶

The “low strength of evidence” label does not mean the benefits are doubtful; it means the studies have design limitations that make it hard to draw the kind of conclusions a randomized controlled trial would allow. You cannot randomly assign people to receive or not receive a medically indicated treatment they are seeking, so most studies are observational. What the existing evidence shows is a consistent direction of effect: people feel better on treatment, and the effect appears to be meaningful rather than trivial.

Athletic Performance on Testosterone

The question of how testosterone therapy affects physical performance in trans men is relevant both for personal fitness goals and for the ongoing debates around sports inclusion. A study of U.S. military service members found that before starting testosterone, trans men performed about 43 percent fewer push-ups and ran 1.5 miles about 15 percent slower than cisgender male peers. After one year of masculinizing hormones, those gaps closed entirely for push-ups and running, and trans men actually exceeded the average cisgender male performance on sit-ups.²⁷

A cross-sectional study comparing trans men on testosterone with cisgender men found that while testosterone concentrations were similar between the groups, trans men still had lower absolute grip strength and lower maximal oxygen uptake. The authors interpreted this as an argument against blanket bans on transgender athletes, noting that the differences were modest and the research landscape is still thin.²⁸ Skeletal frame, muscle fiber composition, and training history all contribute to performance differences that testosterone alone cannot fully erase, nor does it need to for most recreational and competitive contexts. The science here is early and sport-specific data are almost nonexistent.

How Testosterone Changes the Brain

Testosterone does not just reshape the body. Neuroimaging studies have found structural brain changes in trans men during hormone therapy. A review of the evidence reported increases in total brain volume, cortical thickness in several regions, and increased volume in subcortical structures like the thalamus and hypothalamus. White matter tracts also showed changes suggestive of stronger connectivity, particularly in pathways connecting the frontal and parietal lobes.²⁹

A 2024 imaging study added more detail, identifying changes in gray matter density and microstructure across regions including the insula, cingulate cortex, and fusiform gyrus after a median of about four and a half months of treatment. The same study found that trans men reported increased sexual desire on testosterone, and changes in the insula correlated moderately with those desire scores.³⁰ What these structural shifts mean functionally is still largely unknown. Brain imaging studies are good at showing that something changed, but the leap from “this region got thicker” to “this is what it means for daily cognition” is enormous. Many trans men report feeling sharper, more emotionally even, or more comfortable in their own skin on testosterone, but attributing those subjective experiences to specific brain regions is beyond what the current research can support.

Menstrual Cessation and What Happens When It Is Slow

Although most trans men stop menstruating within the first several months of testosterone, a notable minority takes much longer. In one cohort, about twelve percent were prescribed supplemental oral progesterone because their periods persisted, including five individuals who were still menstruating after a full year on moderate-dose weekly injections.³¹ A study of adolescent and young adult trans males found a median time to cessation of about 151 days, or roughly five months, when testosterone was used alone.³²

Persistent menstruation is distressing for many trans men and can feel like the treatment is not working. In practice, clinicians may adjust the testosterone dose, switch formulations, or add a progestin. The goal is amenorrhea, but the body does not always cooperate on the preferred schedule. Knowing that it can take over six months for a substantial portion of people may help set realistic expectations early in treatment.

Adolescent Bone Health and Growth

For younger trans men who begin their medical pathway with puberty blockers before adding testosterone, bone health deserves its own consideration. Puberty blockers pause the estrogen-driven bone mineral accrual that normally accelerates during adolescence, and delaying that process can temporarily lower bone density scores. A review of existing studies found that testosterone administration significantly increases bone density z-scores after at least two years, though in most cases baseline values were not fully restored. An exception was a study in which early-pubertal trans boys who had long-term GnRH agonist treatment followed by three years of testosterone showed improved bone density compared to their pre-treatment baseline.³³ The practical implication is that bone density monitoring matters more for adolescents on this pathway than for adults starting testosterone without prior puberty suppression, and that adequate calcium, vitamin D, and weight-bearing activity are worth emphasizing during the catch-up period.