What are puberty blockers and how are they used in trans care?

• Labour to uphold ban on puberty blockers for trans minors
• Youth gender care a flashpoint in trans rights debate
• In Norway, health body recommends limiting their use

Britain's new Labour government has said it will uphold a ban that stops trans and gender-diverse children from accessing puberty-blocking drugs, a contested treatment for children who wish to transition.

As more adolescents seek to medically transition around the world, parents, doctors and authorities are grappling with what treatment should be made available to them and at what age.

The use of puberty-blocking medication among minors has become a flashpoint in fierce and often polarised debate about trans rights from the United States and Canada, to Spain and Britain.

England's National Health Service ended the routine provision of puberty blockers for children in April.

In May, Britain's previous Conservative government introduced an emergency ban on prescriptions of puberty-blocking drugs to children suffering gender dysphoria - a discomfort that their gender identity does not match their body.

Wes Streeting, appointed health secretary after the centre-left Labour party won national elections this month, said he would defend the ban. It has been challenged in a legal review brought by rights campaigners, who say it risks the safety of trans youth.

Here's what you need to know:

What are puberty blockers?

Puberty-blocking drugs are used to halt the onset of puberty by suppressing the release of the sex hormones testosterone and oestrogen.

Administered by injection or implants, they act as hormone-obstructing agents that hinder the signs of puberty, such as the growth of facial hair and testes or breast tissue growth and the onset of menstruation.

They are sometimes prescribed to young people with gender dysphoria - a discomfort that their gender identity does not match their body - to delay physical changes.

Puberty blockers are not to be confused with cross-sex hormone therapy - which aims to develop rather than suppress secondary sex characteristics to align with preferred gender identity.

Who uses puberty blockers?

The drugs have been used for decades to treat precocious puberty, a rare condition in which a child's body matures early, usually before they turn eight. They have also been approved to treat prostate cancer and endometriosis.

More recently, doctors have prescribed puberty blockers for children experiencing gender dysphoria.

For young people who identify as trans, puberty blockers can be used to "buy time" so they can reflect on their options and can ease the stress of gender dysphoria, according to the World Professional Association for Transgender Health, a global body of doctors specialised in trans people.

A 2020 report found suicidal thoughts were less common in trans adults who had undergone puberty-suppressing treatments in their teen years.

The use of puberty blockers in adolescence can also prevent the need for future gender-affirming surgery, for example for trans men who can avoid mastectomies, or for trans women, Adam's apple reductions.

Are puberty blockers safe?

A 2024 study by the American Physiology Society showed the effects of puberty blockers can be reversed if medication is stopped, but said more research was needed into their long-term effects.

Research from 2022 in the Journal of the Endocrine Society, which looked at several dozen children taking puberty blockers for less than two months, concluded that "later pubertal onset" as a result of puberty blockers "leads to lower adult bone mineral content".

The Provincial Health Services Authority, the publicly funded health service provider in the Canadian province of British Columbia, has found that the medication will temporarily delay growth in height and fertility.

What are the criticisms of puberty blockers?

England's National Health Service ended the routine provision of puberty blockers for children with gender dysphoria on April 1 after a review found insufficient evidence of their safety or clinical effectiveness.

The ban, backed by the new health secretary, is being challenged in the high court, with two claimants arguing it is unlawful.

Finland and Sweden's health bodies decided in 2020 and 2022 respectively to limit use of the drugs for trans minors except in rare cases, citing insufficient scientific basis for their use.

In Norway, a non-governmental health board called in 2023 for hormone treatments for trans children to be limited to research settings, but the country's health agency has not yet acted upon the advice.

Underscoring the issue's political dimension, French media reported in March that a group of conservative senators were calling for the use of puberty blockers to be banned in gender care for patients under-18 following research on the subject. 

Curbs on access to the drugs have alarmed trans rights advocates and parents of trans children, who say limiting access to the medication could force them to seek costly private or unsupervised alternatives.

"All trans young people deserve access to high quality, timely healthcare," LGBTQ+ campaign group Stonewall UK said in response to England's new restrictions.

This article was updated on Monday, July 15 to include the position of Britain's new Labour government.

(Reporting by Joanna Gill in Brussels; additional reporting by Lucy Middleton in London; Editing by Clar Ni Chonghaile.)