Risks of Gender-Affirming Hormones in Adolescents: A Sourced Explainer for Families

TransHealthHub

Sep 14

4 min read

Key Takeaways

The risks of gender-affirming hormones in adolescents sort into three groups: effects that are expected and permanent, effects that are unwanted but manageable, and open questions.
American Medical Association policy, reaffirmed in 2024, calls medical treatment for gender dysphoria, decided between patient and physician, medically necessary under accepted standards.
Bone is the most studied physical question. A 2026 meta-analysis of 751 adolescents found bone density scores fell against a reference population during puberty suppression, then partly recovered.
The largest U.S. study followed 315 young people at four clinics for two years. Depression and anxiety symptoms fell, and serious physical events were uncommon.
Long-term data remain limited. Thirteen evidence reviews have appeared since 2017, and the long run is still incomplete.
Searches here also turn up hormone therapy, masculinizing or feminizing hormone therapy, and supportive care. Those phrases point to one treatment.

The short answer on gender-affirming hormones

The known risks of gender-affirming hormones in adolescents are mostly familiar, monitored ones: blood counts, cholesterol, acne, a dip in bone density scores when puberty is paused first, and reduced fertility. Intended changes that do not reverse are discussed beforehand. What research has not settled is the long run: the studies are recent, small, and short.

At TransHealthHub, we help families categorize and make sense of their worries, rather than handing them a list of dangers or one-off reassurance.

The three categories worth separating

Three separate things get mixed together.

Category	Examples	How it is handled
Intended and permanent	Voice deepening, facial hair, breast growth	Discussed beforehand, not counted as side effects
Unwanted but manageable	Acne, thickened blood, cholesterol	Routine lab work and dose adjustment
Unsettled	Long-term bone, heart, and fertility outcomes	Ongoing monitoring

Our guides to testosterone side effects and estrogen side effects take each medication separately, and our hormone therapy overview covers how treatment starts.

What the largest U.S. study recorded

Before the numbers: if a young person in your life is struggling, support is available now. The 988 Suicide and Crisis Lifeline (call or text 988) and The Trevor Project (1-866-488-7386) are staffed and confidential, and our crisis support page lists more.

Diane Chen and colleagues followed 315 transgender and nonbinary young people aged 12 to 20 at four U.S. clinics for two years after they began testosterone or estradiol, publishing in the New England Journal of Medicine in 2023. Over that period, depression and anxiety symptoms decreased while life satisfaction rose.

The same paper recorded the adverse events. The most common was suicidal ideation, in 11 participants, or 3.5%. Two participants died by suicide during the study. The design was observational with no comparison group, so those events are part of the record, not an effect of the medication. Elevated suicide risk among transgender young people is linked to stigma, rejection, and mistreatment, not to being transgender.

Bone development, the most studied physical question

Bone is where the evidence is deepest, and the finding is a dip then a partial recovery. Daniele Tienforti and colleagues pooled 10 cohorts covering 751 adolescents, most outside the U.S., in a 2026 meta-analysis in JAMA Pediatrics. Lumbar spine z-scores, which compare a young person against a reference population, fell during puberty suppression even though bone density held steady. Once hormone therapy began, bone density rose and z-scores partly recovered.

The authors were careful about what that leaves open. Scores stayed below baseline at the end but were not consistently different in statistical terms, which they described as uncertainty, not a demonstrated persistent deficit. Starting hormone therapy on time was linked to better skeletal outcomes.

What U.S. data on physical risk look like

Small. A 2024 paper in the Journal of Clinical and Translational Endocrinology by Natalie Nokoff and colleagues at the University of Colorado followed 19 transgender adolescents through a year of testosterone. They found no major cardiometabolic changes, including no significant shifts in cholesterol, alongside a rise in red blood cell concentration. That is the scale of most U.S. research here, and why monitoring runs on a schedule.

What is still uncertain

The gap is duration, not direction. In a 2026 Viewpoint in The Lancet, David Matthew Doyle and Annelou de Vries counted 13 evidence reviews of puberty suppression and hormone therapy in adolescents since 2017, seven since 2023.

That uncertainty sits alongside a clear position from U.S. physicians. American Medical Association policy H-185.927, reaffirmed in 2024, states that medical treatment for gender dysphoria, decided through shared decision-making between patient and physician, is medically necessary under generally accepted standards. Thin long-term data argues for monitoring and research, not a finding of harm.

Frequently asked questions

Which risks of gender-affirming hormones in adolescents are permanent? The intended changes, mainly voice and facial hair with testosterone and breast development with estrogen. They are discussed in advance, not counted as side effects.

Do these medications damage bones? The pooled evidence shows a dip against a reference population during puberty suppression and a partial recovery afterward; the long run uncertain.

How often is monitoring done? On a set schedule, more often early on. Specifics belong to the clinical team.