UK authorities have paused a clinical trial on puberty blockers for young people. The medicines regulator warned about unknown long-term biological risks and demanded a minimum age of 14.
The Medicines and Healthcare products Regulatory Agency will meet King’s College London next week. They will review safety concerns before recruitment begins. The Department of Health and Social Care confirmed the pause.
The Cass review had called for the trial after finding weak evidence for benefits. Dr Hilary Cass said only a controlled study could clarify the treatment’s effects.
The government said child safety guides every decision. Experts will examine the evidence before the study can proceed.
King’s College London said the wellbeing of young people remains its priority. The team will work with the regulator to refine the protocol. It described the trial as scientifically rigorous and necessary for better future choices.
Researchers had planned to recruit about 226 participants within three years. The original design allowed children as young as ten. The regulator now wants a stepwise approach that starts at age 14.
NHS England has already ended routine prescriptions of puberty blockers for gender dysphoria. It limits their use to research settings.
Professor Sir Jonathan Montgomery said the regulator aims to strengthen the study, not cancel it. He called the pause a normal safety measure that protects participants.
