Most clinical guidelines recommend starting testosterone at age 16, though some individuals begin earlier and many start at 18 or older. The actual age you can access testosterone depends on a combination of medical guidelines, where you live, and whether you’re pursuing treatment as a minor or an adult.
What Major Medical Guidelines Recommend
The Endocrine Society, which sets the most widely referenced clinical standards, recommends that testosterone can be initiated after age 16 using a gradually increasing dose schedule. Before that happens, a multidisciplinary team of medical and mental health professionals needs to confirm persistent gender incongruence and that the adolescent has sufficient mental capacity to give informed consent.
The guidelines also acknowledge that there may be compelling reasons to start testosterone before 16 in some cases, though published research on hormone treatment before ages 13.5 to 14 is minimal. When treatment does begin earlier, the same requirement for a multidisciplinary team applies. In practice, this means starting before 16 is possible but less common, and providers tend to be more cautious about it.
For adults 18 and older, the process is generally more straightforward. Many clinics use an informed consent model, meaning you can start testosterone after being informed of the risks and benefits and signing a consent form, without needing letters from mental health professionals or lengthy evaluations.
What’s Required for Minors
If you’re under 18, the requirements are more involved. Parental or guardian consent is standard across virtually all providers and jurisdictions. Beyond that, most protocols require a formal diagnosis of gender dysphoria, a psychological evaluation, and confirmation that puberty has progressed to at least Tanner stage 2 (the earliest visible signs of puberty, such as breast budding or the beginning of body hair). The logic here is that puberty needs to have started before cross-sex hormones are introduced.
Some states have particularly detailed requirements. Florida, for example, mandates that minors undergo a psychiatric or psychological evaluation before starting, with suicide risk assessments every three months, lab work every four months, an annual bone density scan, and a hand X-ray to monitor bone growth at least once a year. These represent the more intensive end of the spectrum, but they illustrate what monitoring for minors can look like.
Puberty blockers are a separate, earlier step that some adolescents take before testosterone. Blockers pause natal puberty and are typically started at Tanner stage 2, which can be as young as 10 or 11. Blockers buy time and are considered largely reversible, but they’re distinct from testosterone itself.
State Laws That Restrict Access
Where you live now plays a significant role. As of early 2025, 27 states have enacted laws or policies limiting youth access to gender-affirming care, and roughly half of all trans youth ages 13 to 17 live in one of those states. In 24 of those states, hormone therapy for minors is banned outright, and health care providers face professional or legal penalties for prescribing it. Two states, Alabama and Nebraska, extend their bans to age 18.
Not all restrictions are identical. Arizona and New Hampshire, for instance, only ban surgical treatments for minors and still allow hormone therapy. But in most states with active bans, testosterone is off the table until you turn 18 (or 19 in Alabama and Nebraska). These laws override individual clinic policies, so even a willing provider in a restricted state cannot legally prescribe testosterone to a minor.
If you live in a state with a ban, some families travel to neighboring states for care, though this raises its own logistical and legal questions that vary by state.
What to Expect When You Start
Testosterone is often described as a second puberty, and like first puberty, the full effects take years. The earliest changes tend to show up within weeks to months: oilier skin, changes in sweat and body odor, increased libido, and clitoral growth. Your voice may start cracking or feel scratchy within the first few weeks as it begins to deepen.
Acne typically peaks during the first year and then gradually improves. Facial changes, including fat redistribution that gives the face a more angular appearance, can take two or more years to reach their final result. Body hair growth is one of the slowest changes, sometimes taking five years or longer. People who start testosterone in their late teens or early twenties may see some subtle bone changes, while those who start later in life may experience less overall facial hair development.
Some of these changes are reversible if you stop testosterone, but several are not. Voice deepening, clitoral growth, facial hair growth, and male-pattern hair loss are permanent.
Fertility Considerations Before Starting
Testosterone can affect your ability to conceive in the future, so fertility preservation is something providers should discuss before you begin. For adolescents who have already started natal puberty, egg freezing (oocyte cryopreservation) is an option. This involves a hormonal stimulation cycle and an egg retrieval procedure, which some people find uncomfortable or dysphoria-inducing, but it’s the most established method for preserving future fertility options.
For younger adolescents who have been on puberty blockers and haven’t gone through natal puberty, fertility preservation is currently not possible since mature eggs haven’t developed. Most young people who start puberty blockers go on to begin testosterone without ever going through natal puberty, which means the window for egg freezing may close if it isn’t addressed early. This is one of the more consequential decisions in the process, and it’s worth having a thorough conversation about it before starting any hormonal treatment.