The UK has suspended a clinical trial on puberty blockers after the medicines regulator raised safety concerns. The agency warned about unknown long-term biological risks and called for a minimum age of 14.
The Medicines and Healthcare products Regulatory Agency will meet King’s College London next week. They will review participant wellbeing and the study design. The Pathways trial will not recruit children until they resolve these issues.
The study followed the Cass review on gender care for young people. The review found weak evidence for the benefits of puberty blockers. Dr Hilary Cass said a controlled trial was necessary to clarify the treatment’s effects.
The Department of Health and Social Care said safety remains the main condition. Experts must confirm that the research is both necessary and safe before it begins.
King’s College London said the health of young people and their families remains its priority. The university will continue working with the regulator. It described the trial as scientifically rigorous and essential for better future decisions.
Researchers had planned to recruit about 226 participants over three years. The original design allowed children as young as ten. The regulator now wants a stepwise approach that starts at 14 because of uncertain risks.
NHS England already limits puberty blockers to research settings. Professor Sir Jonathan Montgomery said the pause aims to improve the protocol. He called it a normal safety step in the regulatory process.
