A trans man is a person who was assigned female at birth but whose gender identity is male. Like all transgender people, a trans man experiences a difference between the sex noted on his birth certificate and his internal sense of who he is. Some trans men pursue medical steps to align their body with their identity, while others do not. There is no single way to be a trans man.
Gender Identity vs. Sex Assigned at Birth
When a baby is born, doctors designate the infant as male or female based on physical anatomy. That designation goes on the birth certificate and shapes how the world treats the child from day one. Gender identity, by contrast, is a person’s internal sense of being male, female, or something else entirely. For most people, those two things line up. For trans men, they don’t.
A trans man knows himself to be male even though his birth records say female. This isn’t a choice or a phase. It’s a persistent, deeply felt sense of self. The clinical term for the distress that can accompany this mismatch is gender dysphoria, though not every trans person experiences it to the same degree.
You may also encounter the term “transmasculine,” which is a broader umbrella. Transmasculine includes trans men but also covers nonbinary people who were assigned female at birth and lean toward a masculine identity without identifying fully as male. A trans man, specifically, identifies as a man.
Social Transition
Social transition refers to the everyday, non-medical steps a trans man may take to live as himself. These often come first and can happen at any age. Common elements include adopting a new name and he/him pronouns, changing clothing and hairstyle, and asking friends, family, and coworkers to use the correct name and pronouns.
Some trans men also use chest binders, which are tight garments that flatten breast tissue to create a more masculine chest silhouette. Others use a penile prosthesis, sometimes called packing, to give a masculine contour under clothing. These steps are highly personal. Some trans men do all of them, some do a few, and some focus entirely on social recognition without changing their appearance much at all.
Testosterone Therapy
Many trans men choose to take testosterone, which gradually shifts the body toward typically male physical characteristics. The changes unfold over months and years rather than all at once, and the timeline is fairly well mapped.
In the first few weeks, one of the earliest shifts is an increase in sex drive, which typically plateaus around six weeks. Within three months, body fat begins redistributing away from the hips and toward the abdomen, and muscle mass starts increasing. These changes in fat and lean body mass stabilize around six to twelve months but can continue subtly for years. Voice deepening usually begins within the first few months as well.
Facial and body hair growth is slower, often taking a year or more to become noticeable and continuing to develop for several years. Bone density improvements are detectable after about six months and continue for at least three years. Menstrual periods typically stop within the first few months of treatment.
Testosterone does affect fertility. It lowers the ovaries’ ability to produce estrogen and disrupts the menstrual cycle, reducing reproductive capacity. Trans men who want biological children in the future can explore options like egg freezing before starting hormones, though some people have conceived after pausing testosterone. Birth control is still recommended for trans men on testosterone who have sex that could result in pregnancy, because testosterone alone is not a reliable contraceptive.
Surgical Options
Not all trans men pursue surgery, but for those who do, the most common procedure is chest masculinization, often called top surgery. The goal is to remove breast tissue and reshape the chest for a masculine contour. Johns Hopkins Medicine describes several approaches.
The most widely used technique is the double incision mastectomy, which works well for people with moderate to large amounts of breast tissue. The surgeon makes two horizontal incisions along the natural lines of the chest muscles, removes tissue, and repositions the nipples. It produces a very flat result but leaves visible scars along the lower chest, and nipple sensation may be temporarily or permanently reduced.
For people with very small breasts and no excess skin, a keyhole (periareolar) approach is sometimes possible. The surgeon works through a small incision along the border of the areola, leaving a much less noticeable scar. However, it’s only effective for a narrow range of body types. A third option, the buttonhole technique, preserves nipple sensation by keeping the nipple attached to its nerve supply, though it may leave a small amount of bulk in the chest area. Across all techniques, the risk of a hematoma (a blood clot forming in the tissue) is about 1 to 2 percent.
Lower Surgery
Some trans men also pursue genital surgery, though this is less common than top surgery. The two main options are metoidioplasty and phalloplasty, and they involve very different trade-offs.
Metoidioplasty uses the tissue that has already grown from testosterone therapy to create a small penis. It preserves erogenous sensation, allows natural erections, and in many cases enables standing urination. The result is smaller in size and generally not sufficient for penetrative intercourse, but many patients choose it because the outcome looks and feels more natural. Complication rates are lower overall, with urethral fistulas (small openings where the new urethra doesn’t heal completely) being the most common issue.
Phalloplasty constructs a larger penis using tissue grafted from another part of the body, typically the forearm or thigh. It requires at least two separate surgeries and has a higher complication rate. In one study of 123 patients, 46 percent of those who had a flap-based phalloplasty experienced a documented complication, compared with about 35 percent of those who chose metoidioplasty. The most frequent problems involved infections and issues with erectile implants, which sometimes had to be removed due to skin breakdown.
Preventive Health Considerations
A key principle in trans men’s health care is straightforward: any organ that’s still present needs appropriate screening. A trans man who has not had a hysterectomy still has a cervix and uterus and benefits from cervical cancer screening. A trans man who hasn’t had top surgery, or who had surgery that left some breast tissue, may still need breast or chest screening depending on risk factors.
On cardiovascular health, research so far has not found an increase in heart-related events among trans men on testosterone. The American College of Obstetricians and Gynecologists notes that testosterone therapy does not appear to pose a significant cardiovascular risk, though long-term data is still limited.
Legal Recognition
Changing legal documents is a separate process from medical transition, and the requirements vary widely. In the United States, each state sets its own rules for amending birth certificates and driver’s licenses. Some states allow a simple self-declaration, while others require a court order or documentation from a physician.
At the federal level, U.S. passport policy has shifted significantly. As of 2025, the State Department only issues passports with a sex marker matching the holder’s sex assigned at birth. Passports with an “X” marker are no longer issued, and applications requesting a marker different from the one on the applicant’s birth records may face delays or be denied. Trans men who previously obtained passports with an updated sex marker may be asked to replace them with one reflecting their birth designation. This policy followed an executive order and was upheld after the U.S. Supreme Court stayed a lower court’s injunction against it in November 2025.
State-level documents remain more varied, and some states still allow gender marker changes on birth certificates and IDs through their own processes.