A clinical trial assessing puberty-blocking drugs for gender-questioning children in the UK has established a minimum age of 11 for participation. The Pathways Trial, initially paused in February, will now require female participants to be at least 11 years old and males at least 12 years old, a change prompted by safety concerns raised by the Medicines and Healthcare products Regulatory Agency (MHRA).
The MHRA had previously suggested a minimum age of 14, but discussions with the research team have led to the revised age limits and other strengthened safeguards. The first children are anticipated to be recruited in August, although ongoing legal actions by some clinicians and campaigners could cause delays.
Researchers from King's College London, who are leading the trial, have agreed not to recruit participants until after August 1, allowing legal proceedings to continue. They stated that no child will be able to join the trial without parental consent and that all participants must demonstrate a clear understanding of the intervention, its potential benefits, and risks. The researchers added that while safeguards have been enhanced, including clearer guidance on when the drugs should be stopped and more detailed information on fertility preservation, there are no significant changes to the trial's overall design or conduct.
Puberty blockers, also known as puberty suppressing hormones (PSH), are used to temporarily halt the physical changes of puberty. Their use in individuals under 18 questioning their gender identity was banned in 2024 following concerns about their safety and the evidence base for their effectiveness.
A review conducted in 2024 by Dr. Hilary Cass found that gender medicine had been operating on "shaky foundations." Despite this, Cass has stated that the trial for puberty blockers for under-16s is vital to prevent the inappropriate prescription of drugs, particularly through private sales.
The Pathways Trial, approved by UK regulators and ethics experts in November 2025, aims to recruit children under 16 who are distressed about their gender identity and are currently accessing gender services. The study intends to examine the drugs' impact on participants' physical, social, and emotional well-being.
Some medical professionals have questioned the necessity of the trial, while campaigners are pursuing legal action against the MHRA and other involved parties. These campaigners argue that the trial is unethical and that children cannot provide fully informed consent for a treatment that may affect their future fertility. Professor Sir Jonathan Montgomery, of UCL's Faculty of Health Care Law, commented that legal proceedings are expected to provide further scrutiny and clarify any overlooked issues.
LGBTQ+ charity Stonewall expressed its satisfaction with the modified trial protocol, noting that many young people have experienced prolonged emotional and physical distress since the ban on puberty blockers for those under 18 was implemented.