UK regulators have paused a clinical trial on puberty blockers for children. The Medicines and Healthcare products Regulatory Agency warned about unknown long-term biological risks. It called for a minimum participant age of 14.
The agency will meet King’s College London next week to review safety issues. The Department of Health and Social Care confirmed the delay. The Pathways trial will not recruit participants until the review ends.
The study followed the Cass review into gender care for young people. That review found weak evidence for the drugs’ benefits. Dr Hilary Cass said a controlled trial was the only way to clarify their effects.
Government officials said child safety remains the main condition. Clinicians will examine the evidence before any approval. The trial will proceed only if experts judge it safe and necessary.
King’s College London said young people’s wellbeing guides the project. The team will continue working with the regulator. It said the study uses strict scientific methods and aims to inform future care.
Researchers had planned to enrol 226 participants within three years. The original design allowed children as young as ten. The regulator now wants a step-by-step approach starting at 14.
The trial is one of two planned studies on puberty blockers. NHS England already limits the drugs to research use. Professor Sir Jonathan Montgomery said the pause strengthens the protocol. He called it a normal safety measure.
