In 2024, the UK indefinitely banned the prescription of puberty blockers for children with gender dysphoria, claiming that puberty blockers posed “an unacceptable safety risk” due to their side effects. Puberty blockers are gonadotropin-releasing hormone agonists (GnRHs). They bind to gonadotropin receptors and stop the production of sex hormones such as testosterone and estrogen, which in turn pauses puberty. Puberty blockers are often used to prevent the development of secondary sex characteristics (such as breast growth or facial hair) in people with gender dysphoria, a condition where a person’s gender identity does not align with their assigned sex at birth. This method was developed in the 1990s by Dr. Cohen-Kettenis and is referred to as the Dutch Protocol. According to Mayo Clinic, puberty blockers reduce the need for future surgeries and allow children with gender dysphoria more time to explore their identity. 

The UK’s decision to ban puberty blockers relied heavily on findings of the Cass Review, an independent report conducted by pediatrician Hilary Cass. The review raises concerns about the absence of experimental (in other words, randomized and controlled) trials in the field, noting that most studies conducted on puberty blockers have been observational. Since puberty blockers have only been used for three decades in the treatment of gender dysphoria, there are few long-term studies regarding their side effects (such as reductions in bone density, erratic growth patterns, and heat flashes). Currently, research suggests that reductions in bone density are reversed when people go off of puberty blockers. However, the Cass review emphasizes that other long-term effects on cognitive function and fertility are still unknown. 

All drugs have side effects, and it is important to also consider the benefits of puberty blockers. A recent narrative review evaluated 51 studies on puberty blockers and found that 22 presented moderate to high-quality evidence according to the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach. The review found that puberty blockers successfully prevented the development of secondary sex characteristics, reduced symptoms of depression/suicidal ideation, and improved global functioning, especially when followed by gender-affirming hormone therapy. These benefits are especially important considering the level of need in gender nonconforming populations. According to a 2024 report by The Trevor Project, 46% of gender nonconforming youth seriously considered attempting suicide, and 14% attempted suicide, as opposed to 30% and 7%, respectively, of their cisgender peers. 

The UK is currently pushing for clinical, experimental trials on puberty blockers. In response, a group of Yale pediatricians and researchers claimed that it would be against ethical standards to conduct clinical trials on gender non-conforming youth. Because puberty blockers are banned in the UK, the only way to access them is through said trials. People who are unable to receive gender affirming interventions are thus indirectly coerced into participating. Conducting a reliable clinical trial would also be logistically unfeasible. Puberty blockers have noticeable physiological effects, making blinding (the process to prevent bias by keeping participants or researchers unaware of the assigned medication) impossible. 

The Yale rebuttal also critiqued the emphasis on obtaining “high-quality” evidence through randomized controlled trials. Although observational studies are usually considered low-quality evidence, they can be deemed high-quality under certain conditions. Furthermore, healthcare decisions are not solely informed by “high-quality” evidence. A review of Cochrane systematic reviews found that 86.5% of reviews in the Cochrane database are classified as moderate to low-quality evidence. These reviews are nonetheless consulted in treatments across fields such as anesthesia, lung cancer, schizophrenia, etc. The clinical process is not a linear path from evidence to application, but a negotiation between the patient’s needs, the doctor’s judgement, expert recommendations, and research evidence.

The results of a current UK clinical trial on puberty blockers will take four years to come out. Regardless of intent, the widespread ban of puberty blockers has limited the treatments available to a population at exceptional risk for depression and suicide. In the meantime, it is important for policymakers to find alternative means to address the needs of gender nonconforming individuals.