Campaigners send legal letter calling for puberty blocker trial to be stopped

Campaigners have called on the trial into puberty blockers for children to be stopped, arguing it is unlawful and could harm young people.

The trial could see around 226 young people recruited after it was confirmed last month that ethical and regulatory approval had been granted.

The trial is being undertaken following a recommendation by the Cass Review into children’s gender care, which concluded that the quality of research claiming to show the benefits of such medication for youngsters with gender dysphoria was “poor”.

Baroness Hilary Cass, who led that review, said her report had “uncovered a very weak evidence base” for the benefits of puberty blockers for children and young people with gender dysphoria, but that “given that there are clinicians, children and families who believe passionately in the beneficial effects, a trial was the only way forward to make sense of this”.

But a legal letter has now been sent to regulatory bodies, the Government and the trial researchers calling for it to be stopped.

The letter is on behalf of the Bayswater Support Group – made up of parents and guardians of children and young adults who identify as trans or non-binary – as well as psychotherapist James Esses and Keira Bell, who began taking puberty blockers when she was 16 before later “detransitioning” and who has spoken of the long-term effects such treatments had on her.

They state that the trial “fails to safeguard the rights, safety, and wellbeing of its subjects, who constitute highly vulnerable children” and that it is “unlawful given the limited known benefits of treatment with puberty blockers”.

Arguing there is a “lack of ethical (and hence legal) justification” for the trial, the campaigners have called on the Medicines and Healthcare products Regulatory Agency (MHRA) – which reviewed the trial for approval – to “terminate its authorisation”.

Mr Esses posted on the social networking site X: “We have sent a pre-action letter to those responsible for the trial (including Wes Streeting).

“In it, we demand that this harmful and illegal trial is terminated immediately.”

Both the MHRA and the Health Research Authority (HRA) said they cannot comment on any potential legal proceedings but the latter said the puberty blocker trial “has all the necessary regulatory approvals that it needs to begin” and that the application for the trial “was reviewed in line with well-established legal and national policy frameworks”.

The medicines regulator said “participant safety is always the MHRA’s priority”.

Health Secretary Wes Streeting, has previously said the trial will “provide better evidence for how the NHS can support and treat young people with gender incongruence”.

In a written statement to Parliament in November he acknowledged it is a “challenging issue, where there are understandable concerns around safety, efficacy and consent”, but noted there is “strict eligibility criteria in place – including clinical review and parental consent”.

Conservative leader Kemi Badenoch wrote to Mr Streeting last month saying the medical trial into puberty blockers must be stopped “before more damage is done to children”.

The youngest patients involved in the trial will typically be 10 to 11 for girls and 11 to 12 for boys, with a maximum age of consent at 15 years 11 months, researchers said.

One group will be given puberty blockers for two years, while the other will be given the drugs after a one-year delay.

Researchers expect to see the first patients available for recruitment in the new year, with results expected in around four years.

Some young people could remain on the drugs beyond the trial if deemed “clinically appropriate”, they said.

In a statement after the legal letter, King’s College London’s Institute of Psychiatry, Psychology and Neuroscience (IoPPN), which is leading the study, said: “Clinical care should always be underpinned by robust evidence, and this study will help provide a better understanding of how to treat and care for young people with gender incongruence.”

Puberty blockers are not prescribed on the NHS to children for the treatment of gender dysphoria, after a ban earlier last year was made permanent in December 2024 with the agreement of devolved governments across the UK.