Clinical Investigator Of Puberty-Blocking Drug Warns Of Safety Hazards For Children
Francesco Carta fotografo via Getty Images
Francesco Carta fotografo via Getty Images

A clinical investigator of the drug commonly used off-label to block puberty in trans-identifying adolescents voiced his concerns about administering the drug without conducting proper safety tests.

Dr. Marc B. Garnick, a Harvard professor, oncologist, and co-principal investigator for the drug Lupron, wrote a letter to the editor of the New York Times in support of a recent investigation into the health effects of puberty blocker drugs for adolescents experiencing gender dysphoria.

“The scholarly and well-researched article raises significant safety issues about using puberty blockers in prepubescent and pubescent children as part of gender transitioning,” Garnick argued. 

The letter was one of four accepted in response to the NYT article that described the “long-term physical effects and other consequences” of puberty blockers prescribed to adolescents experiencing gender distress. The other three letters, which were not written by medical professionals, criticized the article as “transphobic.”


Garnick was one of three academic principal clinical investigators of studies that led to the initial FDA approval of Lupron for the treatment of metastatic prostate cancer. He studied the class of drugs, GnRH agonists – which include puberty blockers – for more than four decades. 

GnRH agonists are FDA approved to treat prostate cancer, endometriosis, and precocious puberty – a condition caused by pituitary gland dysfunction in which children begin to sexually mature before age 8 or 9. Lupron has also been used in the past to chemically castrate violent sex offenders.

Doctors have prescribed puberty blockers off-label as a “treatment” for gender dysphoria on an experimental basis. They are not approved for their off-label use in this context – which occurs during a critical window of brain and body development. Much of the existing published data pertain only to precocious puberty patients.

“I can say that physicians are still learning and continue to be concerned about the safety of these agents in adults,” Garnick continued in the letter. “Woefully little safety data are available for the likely more vulnerable younger population.” 

Proponents of “gender-affirming” care claim that puberty blockers are “completely safe,” “reversible,” and only a “pause button on puberty,” despite the absence of any evidence to support these statements. GnRH agonists act to suppress estrogen and testosterone – the hormones responsible for the development of the reproductive system. They also affect the bones, brain, and other parts of the body. 

“Bone loss in adult men who have been on these agents is significant, and a leading cause of morbidity with long-term administration,” Garnick warned. As outlined in the New York Times article, the risk of osteoporosis (bone density loss) is significant when puberty blocking drugs are administered in adolescence.  

“During puberty, bone mass typically surges, determining a lifetime of bone health,” the authors of the article wrote. “When adolescents are using blockers, bone density growth flatlines, on average, according to an analysis commissioned by The Times of observational studies examining the effects.”

Children who begin taking puberty blockers during the first signs of puberty and go on to take cross-sex hormones, which constitutes the vast majority, will result in the permanent loss of fertility and sexual function.

Other safety issues include cognitive, metabolic and cardiovascular effects, still under intense investigation,” said Garnick.

Manufacturers that dominate the U.S. market for puberty blockers refuse to conduct safety trials on their frequently-prescribed, off-label drugs used to treat gender dysphoria in adolescents. Endo International plc and AbbVie Inc have repeatedly declined to conduct safety tests on the puberty blocking drug Lupron.

“The prudent and ethical use of such agents in the younger population should demand that every pubertal or pre-pubertal child be part of rigorous clinical research studies that evaluate both the short-term and longer-term effects of these agents to better define the true risks and benefits rather than relying on anecdotal information,” Garnick concluded.

Endo Pharmaceuticals, Inc., and AbbVie Inc. are currently under investigation in Texas for allegedly advertising and promoting puberty blockers for “unapproved uses without disclosing the potential risks associated with these drugs to children and their parents.” Texas Attorney General Ken Paxton opened the investigation last year under the Texas Deceptive Trade Practices Act.

On the AbbVie website, Lupron is only indicated for treatment of precocious puberty, uterine fibroids, advanced prostate cancer, and endometriosis. However, AbbVie has been active in advancing transgender causes. According to AbbVie’s diversity statement on their website, the pharmaceutical company prioritizes “supporting the LGBTQ+ community in visible ways” and “furthering education around LGBTQ+ issues,” including $50,000 donations to the Trevor Project and the Heartland Alliance that were “used to support programs specifically serving LGBTQ+ populations.”

Additionally, AbbVie is listed as a sponsor of the GenderCool Project, an organization that embraces the concept of “transgender children.” Recently, AbbVie has come under fire for partnering in the transgender film for children, “Mama has a Mustache.” According to its website, the film is “driven completely by audio interviews of kids ages 5-10” and claims that “children are able to experience a world outside of the traditional gender binary.” After writer Christopher Rufo shared the potential conflict of interest to his Twitter followers last month, the pharmaceutical company has been removed from the film’s website.

Many are concerned about the rising number of children and adolescents adopting a transgender identity and seeking medical interventions that may be unnecessary and harmful. Media outlet Reuters published insurance data in October, finding that between 2017 to 2021, 17,683 of the 121,882 children ages 6 to 17 diagnosed with gender dysphoria received puberty blockers or cross-sex hormones. This number was likely a “significant undercount,” Reuters noted, because it only included data collected from insurance claims. 

The director of the pediatric gender clinic at Boston Children’s Hospital made the startling admission that puberty blockers are handed out to children “like candy” to a “skyrocketing” number of new patients, despite the fact that they are known to cause infertility and are not approved for their off-label use by the FDA.

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