UK — The Pathways Trial, which examines the impact of puberty-blocking drugs for children under 16, was paused in February 2026. This action followed safety concerns raised by the Medicines and Healthcare products Regulatory Agency.

The Medicines and Healthcare products Regulatory Agency recommended introducing a minimum age of 14 for participation in the trial. Researchers from King's College London had previously agreed not to recruit participants until after August 1, with the first participants expected to be recruited in August. The trial had been approved by UK regulators and ethics experts in November 2025.

The trial involves children under the age of 16 who are experiencing gender distress and are currently accessing gender services. For birth-registered female participants, the minimum age is 11, and for birth-registered male participants, the minimum age is 12. Parental consent is required for children to take part, and participants must demonstrate an understanding of the intervention, its potential benefits, and risks.

New guidance for the trial specifies conditions for discontinuing the drugs. These conditions include concerns related to bone density, the impact on brain function, or vaginal bleeding. Detailed information will also be provided on methods for individuals to preserve their fertility.

Campaigners are pursuing legal action against the Medicines and Healthcare products Regulatory Agency, the government, and other entities involved in the trial. Sir Jonathan Montgomery, Professor of Health Care Law at UCL, stated, "Legal proceedings are expected to provide further scrutiny." He added, "If there are legal issues that the regulators have overlooked, then it is in everyone's interests that these are clarified as soon as possible."

Dr. Hilary Cass stated, "It is vital that the trial for puberty blockers for under-16s goes ahead." Dr. Cass also said, "We're going to have ongoing charlatans just handing out inappropriate drugs."