UK regulators have halted a clinical trial on puberty blockers for children. They warned about uncertain long-term biological risks and set a minimum age of 14.
The Medicines and Healthcare products Regulatory Agency will meet King’s College London to review safety issues. The Department of Health and Social Care confirmed the pause. The Pathways trial will not recruit participants until experts resolve the concerns.
The study followed the Cass review on gender care. The review found weak evidence for benefits in young people. Dr Hilary Cass said only a controlled trial could clarify the treatment’s effects.
Government officials said participant safety guides every decision. Clinicians will now reassess the scientific evidence. The trial will proceed only if experts confirm it is necessary and safe.
King’s College London said it prioritises the wellbeing of young people and their families. The team will continue working with the regulator. It described the project as rigorous and essential for future clinical decisions.
Researchers had planned to recruit about 226 participants over three years. Earlier plans allowed children as young as ten. The regulator now demands a stepwise approach that begins at 14 because biological safety remains unproven.
NHS England already restricts puberty blockers to research settings. Professor Sir Jonathan Montgomery said the regulator aims to strengthen the study, not cancel it. He called the pause a sign that safety checks are working.
