Gender-questioning children as young as 11 may receive puberty-blocking drugs as part of a King’s College London-led clinical trial assessing their effects, it has been confirmed.
The £11 million Pathways Trial, which launched in November 2025, was paused in February after the Medicines and Healthcare products Regulatory Agency (MHRA) raised concerns about the welfare of younger participants and recommended a minimum participation age of 14.
According to King’s College London, the trial – one of four total studies under Pathways – will investigate the impact of puberty blockers on “the physical, social and emotional wellbeing of young people with gender incongruence.”
Researchers from King’s College London, in conjunction with South London and Maudsley NHS Foundation Trust, have now set a minimum participation age of 11 for birth-registered females and 12 for birth-registered males, aiming to recruit 226 participants.
Participants may receive puberty blockers for up to two years. Recruitment will not begin until after 1 August 2026 while legal proceedings relating to the trial are ongoing.
Puberty blockers are medications used to delay or suppress the onset of puberty. In the UK, the drugs have been prescribed to some children and young people experiencing gender dysphoria, a condition in which a person’s gender identity differs from the sex they were assigned at birth.
The government introduced an indefinite ban on puberty blockers for under-18s for the treatment of gender dysphoria in December 2024. Announcing the decision, Health Secretary Wes Streeting said that it was a “scandal” that they were given to “vulnerable children without the proof that it was safe.”
The study notes that potential risks associated with puberty blockers may include negative effects on fertility, bone health and cognitive development, although the extent of these risks remains an area of ongoing research.
LGBTQ+ rights charity Stonewall said that puberty blockers “may be the most appropriate treatment” and that their use should be “a matter for medical judgement… informed by best medical practices and evidence.”
Both the indefinite ban on puberty blockers and the Pathways Trial were initiated after the Cass Review – an investigation into gender services for children and young people – recommended future research into the subject in 2024 to improve the “poor” quality of existing knowledge.
The review’s author, Dr Hilary Cass, described the trial as “vital” for improving the evidence available to clinicians and that otherwise “inappropriate drugs” may be distributed by private sellers online.
The trial has drawn criticism from some academics, campaigners and human rights groups. An open letter published in February 2026 has been signed by more than 600 people, calling on Vice-Chancellor Shitij Kapur and leading researchers to “reconsider” KCL’s involvement.
The letter argues that the trial’s premise is “ideologically biased” and “treats claims associated with gender identity ideology… as established fact, rather than as hypotheses that remain subject to serious debate.”
When approached for comment by Roar, King’s College London said that:
“The safety and welfare of young people is the highest priority for the PATHWAYS research team. The study has been designed to the highest possible standards, having been reviewed and approved by independent scientists, the Medicines and Healthcare Regulatory Agency (MHRA), the Health Research Authority (HRA) and the Research Ethics Committee.
We have also worked with the MHRA as they further reviewed the trial in February, as we welcome additional scrutiny on this important research. While their review was not based on any new scientific evidence, we have since strengthened patient information and introduced a new minimum age requirement. There were no major changes to the design or conduct of Pathways trial.
The PATHWAYS trial will safely, and robustly, investigate the benefits and risks of puberty suppression for young people with gender incongruence to improve the evidence base and inform NHS healthcare.”
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