UK officials have paused a clinical trial on puberty blockers for children after a safety warning from the medicines regulator. The agency cited uncertain long-term biological risks and called for a minimum age of 14.
The Medicines and Healthcare products Regulatory Agency will hold talks with King’s College London next week. The Pathways trial will not recruit participants until they resolve the concerns, the Department of Health and Social Care said.
The study followed the Cass review, which found weak evidence for the drugs’ benefits in young people. Hilary Cass argued that only a controlled trial could clarify their effects.
Government officials said participant safety remains the priority. Experts will review the scientific evidence before any restart. The trial will proceed only if they confirm it is safe and necessary.
King’s College London said the wellbeing of young people guides the project. The university will work with the regulator during the review. It described the research as rigorous and essential for future clinical decisions.
Researchers had planned to recruit 226 participants over three years. The original design allowed children as young as ten. The regulator now wants a step-by-step approach that begins at 14.
The Cass review led NHS England to end routine use of puberty blockers. Their use is now limited to research.
Health law expert Jonathan Montgomery said the pause aims to strengthen the study. He said the focus on safety shows the regulatory system working properly.
