Puberty-blockers scandal: the ethics of clinical trials
Testing puberty blockers on children is one of the most contested and controversial clinical trials in recent times. These powerful drugs can block puberty, stopping the production of sex hormones in 11–16-year-olds. Their primary use is currently in men with advanced prostate cancer (a non-surgical alternative to removing the testicles) but they have also been used as a method of chemical castration for sex offenders and more rarely licensed for use in young children with dangerous cases of ‘precocious puberty’.
Few believed that the trial, recommended in the Cass Review, would ever pass the very tight ethical guardrails normally applied to clinical research. But, in late 2025, the Pathways trial was commissioned to fill the alleged evidence gap identified by Baroness Cass’s Review. The trial will monitor 226 participants aged 11-16 for emotional wellbeing, mental health, bone density, cognitive progress and physical growth. Critics – including campaigners, politicians and clinicians – have argued that non-clinical recommendations like data from the approximately 2,000 children given blockers by the now closed NHS Gender Identity Development Service (GIDS) should be pursued before a trial is considered. Others point to the increasing number of de-transitioners who can provide an invaluable evidence-source but are often ignored due to their negative experiences.
There are four ethical pillars to any clinical trial: voluntary informed consent, independent ethics oversight, a favourable risk-benefit balance and fair participant selection. Does the Pathways trial meet the threshold of these pillars, especially as those participating are often physically and biologically healthy but are being treated for often complicated and conflicting mental-health complaints? Can a child truly give voluntary informed consent to an intervention whose long-term effects remain scientifically uncertain, including sexual function and fertility? This trial is currently the only route to puberty blockers in the UK, leading some to question how honest children might be about their experiences for fear of losing their only chance at treatment. And what are the legal and financial implications for parents, future governments and the NHS if participants regret taking part when they grow up?
What is perhaps most interesting is that criticism of the trial comes from both directions. Gender-critical voices argue that normal puberty should be treated as a childhood right rather than something to be medically interrupted. Meanwhile, trans-advocacy groups argue that the trial subjects already vulnerable children to repeated psychological assessments that risk re-traumatising them. Does this convergence suggest no version of this trial could serve children well? Or should both sides put their qualms to one side and accept the stated purpose as itself ethical – helping young people, families, and doctors make better-informed decisions, based on clinical evidence rather than politicised prejudice, whichever side one is on in relation to the sex and gender culture wars?
