UK officials have paused a clinical trial on puberty blockers for children after a regulatory warning. The Medicines and Healthcare products Regulatory Agency raised concerns about unknown long-term biological risks. It called for a minimum participant age of 14.
King’s College London sponsors the Pathways trial. It will meet the regulator next week to address the safety issues. The study will not recruit participants until they resolve these concerns.
The government commissioned the trial after the Cass review. That review found weak evidence for the benefits of puberty blockers in young people. Hilary Cass said only a controlled trial could clarify their effects.
The Department of Health and Social Care said child safety remains the priority. Experts will assess the evidence before any recruitment begins. The trial will proceed only if it proves safe and necessary.
Researchers had planned to enrol 226 participants over three years. The original design allowed children as young as ten. The regulator now demands a stepwise approach that starts at 14.
King’s College London said the trial follows strict scientific standards. It aims to build a reliable evidence base for future care decisions.
NHS England already restricts puberty blockers to research use. Professor Sir Jonathan Montgomery said the pause strengthens the protocol and protects participants.
