UK regulators have paused a clinical trial on puberty blockers for children. The Medicines and Healthcare products Regulatory Agency raised safety concerns. It warned of unquantified long-term biological risks. It asked researchers to raise the minimum age to 14.
The Pathways trial will not begin recruitment until officials resolve these issues. The Department of Health and Social Care confirmed the pause. The agency and King’s College London will meet to review the evidence.
The Cass review had recommended the study. It found weak evidence supporting puberty blockers for young people with gender dysphoria. Dr Hilary Cass said only a proper trial could clarify the treatment’s effects.
The regulator now wants a stepwise approach. It argues that researchers have not proven biological safety in younger children. Future trials could lower the age limit if results support that step.
Researchers had planned to recruit 226 participants over three years. The initial design allowed children as young as ten. Officials now question that threshold.
NHS England has already limited puberty blockers to research settings. The Cass review advised ending routine use.
Sir Jonathan Montgomery said regulators aim to improve the protocol, not cancel the study. He said the pause reflects a proper focus on participant safety.
