New Zealand’s government has announced it will stop issuing new prescriptions for puberty blockers from 19 December, bringing its approach in line with a UK clinical review led by Sir Hilary Cass.

Health Minister Simeon Brown confirmed on Wednesday that existing patients in youth gender services will continue to receive hormone suppressants, but no new cases will be accepted until the British review concludes – a process expected to finish by January 2031.

“These changes will ensure a more consistent and carefully monitored approach,” Brown said. “This mirrors steps taken in other countries, such as the United Kingdom, Finland, Norway and Sweden, where additional safeguards have recently been implemented to ensure decisions are made in line with the best available evidence.

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“The government expects existing youth gender services to continue supporting young people and their families, connecting them with healthcare professionals who have specialised expertise and can provide evidence‑based guidance.

“These changes are about ensuring treatments are safe and carefully managed, while maintaining access to care for those who need it.”

While new prescriptions will be paused, gonadotropin‑releasing hormone, commonly known as puberty blockers, will still be available in clinical settings for other conditions such as early‑onset puberty, endometriosis and prostate cancer, where appropriate.

Brown explained the decision has been driven by what he described as a “lack of high‑quality evidence” on the benefits of puberty blockers. He said Cabinet had agreed to delay new prescriptions until the UK’s National Health Service completes its clinical trial, which began this year.

The UK review, prompted by paediatrician Hilary Cass’s assessment of gender medicine, raised serious questions about the drugs’ effectiveness, concerns that were later amplified in a methodological critique from Yale Law School researchers.

In Australia, a separate review into best practices for gender medicine is underway, led by the National Health and Medical Research Council. Health Minister Mark Butler commissioned the inquiry following a move by Queensland to suspend access to puberty blockers; its findings are expected by mid‑next year.

Transgender Health Aotearoa vice‑president Elizabeth McElrea warned the change could be damaging: she feared it would “lead to worsening mental health, increased suicidality and dysphoria for gender diverse children and young people”.

The number of New Zealanders being prescribed puberty blockers has already fallen, from 140 in 2021 to 113 in 2023.

New Zealand First praised the decision. Associate Health Minister Casey Costello said: “We’ve seen the evidence. Puberty blockers cause irreversible harm to bone density, fertility, brain development, and future sexual function. Yet bureaucrats defend them, bowing to activist pressure instead of listening to common sense. … Nothing is more important than protecting the health and wellbeing of our children.”

The announcement follows recent comments by former Australian Family Court chief justice Diana Bryant, who expressed regret over her 2013 ruling that enabled children to access puberty blockers without court approval.

She said: “If I were deciding the case now and had the evidence that’s now becoming available, I certainly doubt I would have come to the conclusion we (did).”