Skip to content

Puberty blockers can’t be started at 18 when youth have already developed: experts

The medication has been in the spotlight since Smith announced plans to ban it for children under 15
Alberta Premier Danielle Smith speaks in Ottawa on Monday, Feb.5, 2024. THE CANADIAN PRESS/Sean Kilpatrick

Puberty blockers have been in the spotlight since Alberta Premier Danielle Smith announced plans last week to ban the medications for children 15 and younger, unless they have already started the treatment.

Smith’s views about gender-affirming care have drawn criticism from Prime Minister Justin Trudeau but support from federal Conservative Leader Pierre Poilievre, who says puberty blockers should only be provided after age 18. Here’s what health-care professionals say about the medications and why they are used.

What are puberty blockers and how long have they been used?

Puberty blockers are given by injection to youth experiencing gender dysphoria, where a person’s gender identity does not match the sex they were assigned at birth. The medications block physical changes such as breast development due to estrogen or a deepening voice from testosterone.

Dr. Daniel Metzger, a pediatric endocrinologist at BC Children’s Hospital, said the blockers were initially used in the 1990s to delay puberty for children who started developing sexual characteristics as young as three.

Physicians in the Netherlands started administering the medications for gender non-conforming youth in the 1990s before the Vancouver hospital was the first to use them in Canada about 26 years ago, Metzger said.

The effects of puberty blockers are reversible if they are stopped, but taking them allows youth time to decide if they want to continue gender-affirming surgeries, some of which are irreversible.

Around what age are puberty blockers typically administered?

The average age that youth assigned female at birth start puberty is 10 while those assigned male typically start at 11, Metzger said.

“That would be the earliest we would consider using blockers in kids if their body was starting to change and they had gone through the assessment process that we use to decide who would benefit from blockers,” he said.

Those born as girls can become “super distressed” about getting curvy and having their period while youth assigned male are often fearful of becoming hairy as their testicles and penis start to get bigger due to a mismatch between the body and the brain, he said.

“Their care involves the family, the medical system and the mental health system. It doesn’t involve politicians,” said Metzger.

Starting puberty blockers at 18, as Poilievre has suggested, would be “cruel” and “missing the boat,” said Metzger so there’s no point in starting them.

He said long wait lists to see health-care providers already means youth don’t start treatment until age 15 or 16 when their sex characteristics have already developed.

By then, adolescents who are born a girl or boy but identify as the opposite gender have endured years of “emotional torment” and would only have surgery as an option to counter body changes, he said.

“If you deprive someone of blockers until they’re 18, you have made an irreversible decision yourself by forcing a child to go through puberty and forcing them to have body changes that are anathema to them.”

What are the criteria for starting puberty blockers and how often are they given?

Mental health providers must ensure adolescents understand what it means to consent to treatment, including having a puberty blocker regularly injected in their leg. They must also understand the risks and benefits of the treatment and that the blockers can be stopped, allowing puberty to continue.

“They’ve socially transitioned, but all of a sudden they’re getting breasts that they don’t want or they’re getting a penis that’s starting to grow, and they’re getting very upset. So that’s when we would introduce blockers.”

The medications are injected either once a month or every three months but a new formulation that has yet to used would allow the treatment every six months, Metzger said.

What are some potential side-effects?

Puberty blockers, which are also used for certain types of cancers and for endometriosis to limit estrogen, can affect calcium metabolism and decrease bone mineral density, possibly increasing risk of osteoporosis later in life for young patients, Metzger said.

“Teenagers’ bones are putting calcium into their piggy bank very rapidly so they don’t have osteoporosis down the road. When we interrupt puberty for a while, those processes go back to a prepubertal state and there’s a stall in putting calcium in their bones.”

However, adding a hormone — either estrogen or testosterone — for those who may have been on blockers for about two years retriggers puberty, allowing their bones to start re-accumulating calcium, he said.

“You can make up for the time lost and that’s part of what we talk about when we discuss with families the risks and benefits. No drug is without risk. These are kids who are very vulnerable, that can have a huge mental health burden, that are very dysphoric about their bodies.”

Fertility is an important issue when it comes to blockers, Metzger said.

“If you’re barely into puberty, you have no fertility and we’re turning it off. The only way to turn it back on is to go through puberty.”

Transgender boys who have already started their period are typically not given blockers but use a cheaper, easier method — typically the birth control pill or an intrauterine device or IUD, Metzger said.

Trans girls who are older can store their sperm for later use, he said.

“Again, we’re talking risk-benefit here. It’s one of the hardest things I think parents have to hear is we’re interrupting this kid’s fertility. Ten-year-old kids don’t have any thoughts about having kids down the road, generally.”

How does lack of access to gender-affirming care affect trans youth or those experiencing gender dysphoria?

Elizabeth Saewyc, a professor at the University of British Columbia’s school of nursing and senior author of a national trans youth survey in 2019, said 71 per cent of more than 1,500 respondents aged 14 to 25 said they needed mental health services in the previous year but did not get them.

That survey also showed that 30 per cent of youth attempted suicide in the previous year, Saewyc said.

For those with limited access to a family doctor or long waits to see a mental health provider, gender-affirming care including puberty blockers should not be delayed for too long because the emotional toll would be too high, she said.

“None of this is quick. It doesn’t make sense to say, ‘No, not until you’re 18,’ from a medical perspective.”

Politicizing medical care could push some trans adolescents into silence when they may already not be getting support at home or school, where they could be bullied, Saewyc said.

“The misinformation out there is really astounding,” she said about puberty blockers. “It gets worrying when our politicians take up some ideas without actually vetting the accuracy of what they’re saying.”

If you or someone you know is thinking about suicide, support is available 24/7 by calling or texting 988, the national suicide prevention helpline.

This report by The Canadian Press was first published Feb. 8, 2023.

Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.

Camille Bains, The Canadian Press