UK officials have paused a clinical trial on puberty blockers for young people after regulatory intervention. The medicines regulator warned about unknown long-term biological risks and called for a minimum age of 14.
The Medicines and Healthcare products Regulatory Agency will hold talks with King’s College London next week. The Department of Health and Social Care confirmed that recruitment will not begin until they resolve the concerns.
The study followed a recommendation from the Cass review into gender care for children. The review found weak evidence for the claimed benefits of puberty blockers. Hilary Cass said a controlled trial offered the only reliable way to clarify outcomes.
Government officials said participant safety remains the main condition for approval. Clinicians will now examine the new evidence before any trial starts.
King’s College London said it will work closely with the regulator. The university described the project as scientifically rigorous and focused on better future decisions for patients and doctors.
Researchers had planned to enrol 226 young people over three years. The original design allowed participants as young as ten, although screening would likely select older teenagers. The regulator has asked for a step-by-step approach that begins at age 14.
NHS England already limits puberty blockers for minors to research settings. Health law professor Sir Jonathan Montgomery said the pause strengthens the protocol and shows the safety system working.
