The National Health Service in England started restricting gender treatments for children this month, making it the fifth European country to limit the medications because of a lack of evidence of their benefits and concern about long-term harms.

England’s change resulted from a four-year review released Tuesday evening by Dr. Hilary Cass, an independent pediatrician. “For most young people, a medical pathway will not be the best way to manage their gender-related distress,” the report concluded. In a related editorial published in a medical journal, Dr. Cass said the evidence that youth gender treatments were beneficial was “built on shaky foundations.”

The N.H.S. will no longer offer drugs that block puberty, except for patients enrolled in clinical research. And the report recommended that hormones like testosterone and estrogen, which spur permanent physical changes, be prescribed to minors with “extreme caution.” (The guidelines do not apply to doctors in private practice, who serve a small fraction of the population.)

England’s move is part of a broader shift in northern Europe, where health officials have been concerned by soaring demand for adolescent gender treatments in recent years. Many patients also have mental health conditions that make it difficult to pinpoint the root cause of their distress, known as dysphoria.

In 2020, Finland’s health agency restricted the care by recommending psychotherapy as the primary treatment for adolescents with gender dysphoria. Two years later, Sweden restricted hormone treatments to “exceptional cases.”

In December, regional health authorities in Norway designated youth gender medicine as a “treatment under trial,” meaning hormones will be prescribed only to adolescents in clinical trials. And in Denmark, new guidelines being finalized this year will limit hormone treatments to transgender adolescents who have experienced dysphoria since early childhood.

Several transgender advocacy groups in Europe have condemned the changes, saying that they infringe on civil rights and exacerbate the problems of overstretched health systems. In England, around 5,800 children were on the waiting list for gender services at the end of 2023, according to the N.H.S.

“The waiting list is known to be hell,” said N., a 17-year-old transgender boy in southern England who requested to withhold his full name for privacy. He has been on the waiting list for five years, during which time he was diagnosed with autism and depression. “On top of the trans panic our own government is pushing, we feel forgotten and left behind,” he said.

In the United States, Republican politicians have cited the pullback in Europe to justify laws against youth gender medicine. But the European policies are notably different from the outright bans for adolescents passed in 22 U.S. states, some of which threaten doctors with prison time or investigate parents for child abuse. The European countries will still allow gender treatments for certain adolescents and are requiring new clinical trials to study and better understand their effects.

“We haven’t banned the treatment,” said Dr. Mette Ewers Haahr, a psychiatrist who leads Denmark’s sole youth gender clinic, in Copenhagen. Effective treatments must consider human rights and patient safety, she said. “You have to weigh both.”

In February, the European Academy of Paediatrics acknowledged the concerns about youth gender medicine. “The fundamental question of whether biomedical treatments (including hormone therapy) for gender dysphoria are effective remains contested,” the group wrote. In contrast, the American Academy of Pediatrics last summer reaffirmed its endorsement of the care, stating that hormonal treatments are essential and should be covered by health insurers, while also commissioning a systematic review of evidence.

Europeans pioneered the use of gender treatments for young people. In the 1990s, a clinic in Amsterdam began giving puberty-suppressing drugs to adolescents who had felt they were a different gender since early childhood.

The Dutch doctors reasoned that puberty blockers could give young patients with gender dysphoria time to explore their identity and decide whether to proceed with hormones to ultimately transition. For patients facing male puberty, the drugs would stave off the physical changes — such as a deeper voice and facial hair — that could make it more difficult for them to live as women in adulthood. The Dutch team’s research, which was first published in 2011 and tracked a carefully selected group of 70 adolescents, found that puberty blockers, in conjunction with therapy, improved psychological functioning.

That study was hugely influential, inspiring clinics around the world to follow the Dutch protocol. Referrals to these clinics began to surge around 2014, though the numbers remain small. At Sweden’s clinic, for example, referrals grew to 350 adolescents in 2022 from around 50 in 2014. In England, those numbers grew to 3,600 referrals in 2022 from 470 in 2014.

Clinics worldwide reported that the increase was largely driven by patients raised as girls. And unlike the participants in the original Dutch study, many of the new patients did not experience gender distress until puberty and had other mental health conditions, including depression and autism.

Given these changes, some clinicians are questioning the relevance of the original Dutch findings for today’s patients.

“The whole world is giving the treatment, to thousands, tens of thousands of young people, based on one study,” said Dr. Riittakerttu Kaltiala, a psychiatrist who has led the youth gender program in Finland since 2011 and has become a vocal critic of the care.

Dr. Kaltiala’s own research found that about 80 percent of patients at the Finnish clinic were born female and began experiencing gender distress later in adolescence. Many patients also had psychological issues and were not helped by hormonal treatments, she found. In 2020, Finland severely limited use of the drugs.

Around the same time, the Swedish government commissioned a rigorous research review that found “insufficient” evidence for hormone therapies for youth. In 2022, Sweden recommended hormones only for “exceptional cases,” citing in part the uncertainty around how many young people may choose to stop or reverse their medical transitions down the line, known as detransitioning.

Even the original Dutch clinic is facing pressure to limit patients receiving the care. In December, a public documentary series in the Netherlands questioned the basis of the treatments. And in February, months after a far-right political party swept an election in a country long known as socially liberal, the Dutch Parliament passed a resolution to conduct research comparing the current Dutch approach with that of other European countries.

“I would have liked that the Netherlands was an island,” said Dr. Annelou de Vries, a psychiatrist who led the original Dutch research and still heads the Amsterdam clinic. “But of course, we are not — we are also part of the global world. So in a way, if everybody is starting to be concerned, of course, these concerns come also to our country.”

In England, brewing concerns about the surge of new patients reached a boiling point in 2018, when 10 clinicians at the N.H.S.’s sole youth gender clinic, known as the Tavistock Gender Identity Development Service, formally complained that they felt pressure to quickly approve children, including those with serious mental health problems, for puberty blockers.

In 2021, Tavistock clinicians published a study of 44 children who took puberty blockers that showed a different result from the Dutch: The patients given the drugs, on average, saw no impact on psychological function.

Although the drugs did not lessen thoughts of self-harm or the severity of dysphoria, the adolescents were “resoundingly thrilled to be on the blocker,” Dr. Polly Carmichael, the head of the clinic, said at a 2016 conference. And 43 of the 44 study participants later chose to start testosterone or estrogen, raising questions about whether the drug was serving its intended purpose of giving adolescents time to consider whether a medical transition was right for them.

In 2020, the N.H.S. commissioned Dr. Cass to carry out an independent review of the treatments. She commissioned scientific reviews and considered international guidelines of the care. She also met with young people and their families, trans adults, people who had detransitioned, advocacy groups and clinicians.

The review concluded that the N.H.S.’s standard of care was inadequate, with long waiting lists for access to drug treatments and few routes to address the mental health concerns that may be contributing to gender distress. The N.H.S. shuttered the Tavistock center last month and opened two new youth gender clinics, which Dr. Cass said should have a “holistic” approach, with more support for those with autism, depression and eating disorders, as well as psychotherapy to help adolescents explore their identities.

“Children and young people have just been really poorly served,” Dr. Cass said in an interview with the editor of The British Medical Journal, released Tuesday. She added, “I can’t think of another area of pediatric care where we give young people potentially irreversible treatments and have no idea what happens to them in adulthood.”

The changes enacted by the N.H.S. this month are “an acknowledgment that our concerns were, in fact, valid,” said Anna Hutchinson, a clinical psychologist in London who was one of the Tavistock staff members who raised concerns in 2018. “It’s reassuring that we’re going to return to a more robust, evidence-based pathway for decisions relating to these children.”

Some critics said that Europe, like the United States, had also been influenced by a growing backlash against transgender people.

In England, for example, a yearslong fight over a proposed law that would have made it easier for transgender people to change the gender on their identification documents galvanized a political movement to try to exclude transgender women from women’s sports, prisons and domestic violence shelters.

“The intention with the Cass review is to be neutral, but I think that neutral has maybe moved,” said Laurence Webb, a representative from Mermaids, a trans youth advocacy organization in Britain. “Extremist views have become much more normalized.”

Other countries have seen more overt attacks on transgender rights and health care. In 2020, Hungary’s Parliament passed a law banning gender identity changes on legal documents. Last year, Russia banned legal gender changes as well as gender-related medical care, with one lawmaker describing gender surgeries as the “path to the degeneration of the nation.”

In France this year, a group of conservative legislators introduced a bill to ban doctors from prescribing puberty blockers and hormones, with punishments of two years’ imprisonment and a fine of 30,000 euros, or about $32,600. And on Monday, the Vatican condemned gender transitions as threats to human dignity.