The decision to set a minimum age threshold for participation in a UK clinical trial evaluating puberty-blocking drugs has sparked controversy among clinicians and campaigners. Children as young as 11 will now be eligible to join the Pathways Trial, which aims to investigate the impact of these treatments on physical, social, and emotional wellbeing.
The trial, approved by UK regulators and ethics experts in November 2025, was initially paused in February 2026 after the Medicines and Healthcare products Regulatory Agency (MHRA) raised safety concerns. The MHRA had suggested introducing a minimum age of 14, where previously no lower age limit had been defined. Discussions with the research team from King's College London have since led to the strengthening of several safeguards, including the participation age and clearer guidance on when the drugs should be discontinued, for instance, if concerns arise regarding bone density, brain function, or vaginal bleeding. Detailed information on fertility preservation will also be provided.
Recruitment for the trial is anticipated to commence in August, although this timeline could be affected by ongoing legal action. Some clinicians and campaigners are challenging the trial's safety and ethics, arguing that children cannot provide fully informed consent for a treatment that could impact their future fertility. Professor Sir Jonathan Montgomery, Professor of Health Care Law at UCL, noted that legal proceedings are expected to provide further scrutiny, clarifying any potential oversights by regulators.
The introduction of the minimum age follows a broader shift in the provision of gender-affirming care for young people in the UK. Puberty blockers for individuals under 18 questioning their gender identity were banned in 2024, a decision prompted by the independent review led by Dr Hilary Cass. The Cass Review found that gender medicine had been operating on “shaky foundations” due to a lack of robust evidence for treatments, raising significant safety concerns about puberty-suppressing hormones (PSH).
Despite the legal challenges, Dr Hilary Cass has emphasised the importance of the trial for under-16s, stating it is “vital” to prevent the private sale of inappropriate drugs, particularly online. An LGBTQ+ charity, Stonewall, has expressed satisfaction with the modified trial protocol, highlighting that many young people have been left in a state of “emotional and physical distress” since the 2024 ban, and that no one wishes to see this distress prolonged.
Participants in the trial will require parental consent and must meet other eligibility criteria, including demonstrating a comprehensive understanding of the intervention and its potential benefits and risks. Researchers have stated they welcome scrutiny of studies involving children and young people and have strengthened patient safeguards as part of their commitment to transparency and responsible practice.