Puberty blockers: The facts and the myths

Puberty blockers. 

Sadly, they are not a medication that helps block out all those cringeworthy middle school memories. They are medications, sometimes used by transgender adolescents, to temporarily pause puberty.

But in the political debate around gender-affirming care for youth, discussion of puberty blockers is often saturated with rhetoric, creating confusion and generating misinformation.

So, PolitiFact wanted to cut through the noise and answer some of the big questions around these controversial drugs: What are they, when and why are they prescribed to minors,  what do we know about their potential adverse effects, and what is the medical community’s perspective?

A: This answer is easy – none!

Before puberty, neither the Endocrine Society, American Academy of Pediatrics, nor the World Professional Association for Transgender Health recommend any hormonal or surgical interventions. But because gender identity can form early in life, medical organizations say it is important to support families when children strongly assert a gender identity different from the sex they were assigned at birth. 

Support can, but does not always, include a social transition that could include things such as using a different name or pronoun, wearing gender-affirming clothing, or getting a new haircut. The World Professional Association for Transgender Health’s standards of care state that this should be initiated by the child and emphasizes the role that mental health providers can play in supporting and helping families facilitate a healthy social transition. But the organization also notes that identity can change and evolve and encourage parents to leave room for a child to change their mind.

Existing research shows mental health benefits among kids who socially transition, which is improved by supportive families and communities. 

A: Puberty blockers are a lot like what they sound like — they pause or suppress the body from releasing the hormones that lead to changes in the body that accompany puberty.

The most common medication for pubertal suppression are gonadotropin-releasing hormone agonists (GnRHa), which send signals to the pituitary gland to pump the brakes on producing sex hormones such as testosterone and estrogen.

GnRHa have been FDA-approved since 1985, and they are used to treat prostate cancer and endometriosis in adults. Since 1981, they have also been used to treat "precocious puberty," which is when kids start going through early puberty — around ages 6 or 7. Research in this patient population has taught physicians a lot about how puberty blockers work and shown that they can be used safely, said Dr. Jason Rafferty, a psychiatrist and pediatrician at Brown University.

"The use of GnRHas in individuals with central precocious puberty is regarded as both safe and effective, with no known long-term adverse effects," according to the World Professional Association for Transgender Health’s most recent standards of care. 

Use of GnRHa in transgender kids is considered an "off-label" use because the medication was not designed for that purpose. Physicians first started prescribing blockers to this population in 1997 in the Netherlands, but in the ensuing years, the body of research documenting its effects has grown.

Experts explained that after puberty blockers are stopped, sex hormone production and puberty resumes. For this reason, numerous major medical organizations in the U.S. consider these treatments "reversible."

A: Major medical organizations advise that puberty blockers be prescribed only once the first signs of puberty can be seen, called Tanner Stage 2, which is marked by the budding of breasts and an increase in testicular volume.

Kids start puberty at a wide range of times, generally from 8 to 14 years old.

Puberty blockers do not reverse development that has already occurred, but they stop further progression, so they make the biggest difference if prescribed in puberty’s earlier stages. This can also prevent the need for gender transition-related surgeries in the future.

Experts noted that most of the patients they encounter are in puberty’s late stages, when blockers can stop menstruation or facial hair growth but have less effect on irreversible physical changes.

A: The World Professional Association for Transgender Health lists criteria that should be met before medical providers prescribe puberty blockers.

For example, the patient must meet the diagnostic criteria for gender incongruence as laid out by the World Health Organization, and that experience must be evident and sustained over time. Another guideline is that adolescents must demonstrate "emotional and cognitive maturity required to provide informed consent." Also, providers must address any mental health concerns patients have that may interfere with their treatment or ability to consent. And all adolescent patients must be informed about potential reproductive effects, including loss of fertility.

Other medical organizations such as the Endocrine Society have similar criteria. 

Some of these measures are subjective and assessed by the provider, said Dr. Christina Roberts, a pediatrics professor at the University of Missouri-Kansas City School of Medicine, such as the severity or chronic nature of the gender incongruence, the patient’s "cognitive maturity," and how well additional mental health concerns have been addressed. These judgements are made in partnership with the patient’s parents and mental health care providers, said Roberts.  

"As physicians, we are trained to help families make difficult decisions weighing risks and benefits in the face that scientific understanding continues to evolve," said Rafferty. "Puberty blockers are no different…we have to weigh these considerations in the context of each individual patient and their family."

Because puberty blockers’ effects are reversible, the threshold for receiving them is lower than it would be in later teenage years, should an adolescent want to progress to hormones or surgery.

Some people have claimed online that puberty blockers are given out without adequate screening. An Endocrine Society spokesperson said the organization advises that the decision to start puberty blockers be "made only after extensive medical and mental health evaluations, extended discussions with the patient and their family, and a consideration of the potential risks and benefits of beginning or not beginning therapy."

A: Puberty sets off a tidal wave of changes in the body — more breast tissue, rounder hips, facial hair, a deeper voice and changes in genitalia. These changes further distinguish boys from girls. For people whose sex doesn’t match their gender identity, it can be a distressing period.

The Endocrine Society argues that pausing development with puberty blockers can relieve the psychological distress that comes with gender incongruence and allow more time for a patient, family members and providers to consider options.  

Roberts said puberty blockers have in some cases been linked to improved mental health. At the same time, giving patients extra time can allow adolescents to "engage in therapy and gain more experience living in their affirmed gender to help consolidate their gender identity." 

Given high rates of mental health issues, including suicidal ideation among transgender youth, this care can be "life-saving," an Endocrine Society spokesperson said. 

"It is also important to note that puberty blockers are a temporary solution," said Rafferty, "from day one, the discussion needs to be future oriented towards exploring gender and weighing options for the next stage of treatment." 

A: Puberty blockers on their own do not affect fertility. When blockers are stopped, puberty will resume along with normal sexual function and fertility. But if a teen decides to go directly from blockers to cross-sex hormones, which can affect fertility, patients can risk not having mature eggs or sperm to preserve, depending on their age when they started treatment.

For this reason, medical experts and organizations like the Endocrine Society recommend that transgender youth are "fully informed of fertility preservation options prior to initiating puberty-delaying treatment." 

"Developmentally, no one would expect a child at the onset of puberty to know or even comprehend such family planning decisions," said Rafferty, "but with support and discussion over time, with the adolescent and their family, this is part of the decision-making process to determine what the next phase of treatment will look like."

As for chemical castration, because the medications pause sex hormones, a lowered sex drive and lack of erections is normal for the few years an adolescent is taking them. But this will end when a patient stops taking the medication.

But because these medications reduce libido, GnRHa have been used to reduce the sex drive in adult sex offenders.

A: The two biggest unknowns about the health effects of puberty blockers relate to the bones and the brain.

"For development of strong bones exposure to sex hormones is needed," said Dr. Angela Turpin, a pediatric endocrinologist in Missouri. Puberty blockers pause those hormones at a critical time in bone development, which has led to reduced bone density in adolescents who take the medication.

Follow-up research shows bone density improves for people who continue on to cross-sex hormone therapy, especially in trans men. 

"The jury is still out on whether there is adequate, what we call ‘bone density catch-up,’ once the blocker is discontinued," Turpin said.

Researchers want to know more about whether these patients will have caught up in adulthood, or suffer from weakened bones or be at greater risk for fractures. Data shows that the longer a patient is on blockers, the greater risk of the adverse effects.

Another concern stems from a few studies that showed neurodevelopmental changes in mice and sheep that were put on blockers during puberty, affecting things such as spatial memory, stress responses and anxiety- and depression-related behaviors. These studies do not necessarily translate to humans, but they still raise questions that researchers say merit further study.

If any changes do occur, people may grow out of them, but "the concern is, are we causing neurocognitive changes that can't be undone?" said Turpin. "And we don't have the answer to that."

But doing nothing may not be the answer, either, Turpin said. The stress, self-harm and suicidal ideation that can accompany gender dysphoria could be considered "toxic stress," which "can weaken the architecture of the developing brain, which can lead to lifelong problems in learning, behavior, and physical and mental health."

But research on the long-term neurocognitive outcomes of those given and denied access to puberty blockers does not yet exist. 

"One flawed belief is that ‘reversible’ means ‘placebo,’" said Rafferty, "but to be clear, puberty blockers have risks which is why they are prescribed medications requiring the medical expertise and monitoring of a physician."