England's NHS halts puberty blockers for transgender youth amid research efforts

England's National Health Service has banned the use of puberty blockers for the treatment of gender dysphoria or gender incongruence in transgender minors.

The NHS has not stated it will restrict puberty blockers for non-transgender children and young people.

An NHS spokesperson told ABC News the agency hopes to have a study into the use of puberty blockers in place by December of this year, with eligibility criteria yet to be decided.

The agency said it made the move after considering an evidence review conducted by England's National Institute for Health and Care Excellence.

"We have concluded that there is not enough evidence to support the safety or clinical effectiveness of puberty suppressing hormones to make the treatment routinely available at this time," an NHS spokesperson told ABC News in a statement.

Less than 100 young people in England are currently prescribed puberty blockers by the NHS and will be able to continue their treatments, according to the BBC.

Clinicians will also be able to apply for the treatment for their patients under NHS England's Individual Funding Request process, the agency said.

When children experiencing gender dysphoria or gender incongruence reach puberty, physicians told ABC News that families and their care providers sometimes consider the use of puberty blockers to delay the development of gendered characteristics, including the growth of breasts and facial hair, as well as changes in a person's voice.

Physicians and researchers told ABC News in a past interview that puberty blockers are a decades-old practice that has been widely used on children who experience puberty earlier than what is typical.

The Endocrine Society, an international organization of more than 18,000 endocrinologists, calls the medication "fully reversible." Once blockers are stopped, puberty continues with little to no proven side effects, according to health professionals.

"Puberty blockers allow more time to explore gender identity" and allow families to determine their plans for the future regarding gender and gender-affirming care, Endocrine Society guidelines say.

The Endocrine Society says the risks of using puberty blockers include low bone mineral density, headaches, hot flashes, fatigue and mood alterations.

Professionals who spoke with ABC News said they haven't seen fertility issues in people who temporarily use puberty blockers. However, it's stated as a risk by the Endocrine Society based on when puberty blockers are used.

All medications, surgeries or vaccines come with some kind of risk, and gender-affirming care is no different, according to physicians. However, knowing the risks and benefits of treatment -- and of not treating a condition -- can help families make an informed decision, physicians say.

The gender-affirming care guidelines from the World Professional Association for Transgender Health and the Endocrine Society state physicians should thoroughly warn patients about the potential for reduced fertility before administering hormone blockers and hormone therapy.

Major medical associations in the United States, including the American Academy of Pediatrics, the American Medical Association, the American Academy of Child and Adolescent Psychiatry and others agree that gender-affirming care is safe, effective, beneficial and medically necessary.

Studies show transgender youth are more likely to experience anxiety, depressed moods, and suicidal ideation and attempts, often due to gender-related discrimination and gender dysphoria.

Some studies, including research from the Pediatrics and LGBT Health journals, have shown that gender dysphoria and social motivation improved significantly with puberty blockers, and self-harm and suicidality decreased.

In the U.S., at least 23 states have restricted gender-affirming care, according to the Human Rights Campaign: Alabama, Arizona, Arkansas, Florida, Georgia, Idaho, Iowa, Indiana, Kentucky, Louisiana, Mississippi, Missouri, Montana, Nebraska, North Carolina, North Dakota, Ohio, Oklahoma, South Dakota, Tennessee, Texas, Utah and West Virginia.

However, several states have had their policies blocked by legal challenges.

Critics of these U.S. laws say they are concerned about the impact such bans can have on the mental and physical well-being of transgender youth, a small and already marginalized population.

Supporters of these laws say trans youth should wait until they're older to make decisions about their health.