Puberty Blockers

How many children are being treated with puberty blockers in Canada?

The numbers of children being treated with puberty blockers in Canada is unknown, but given that the rise of gender dysphoria in Canadian is similar to that in other western countries like the US and UK, it is expected to be growing at rates of 1000’s of % over the past 5-10 years. 

Puberty blockers are being offered to children at the first visit to a gender clinic in 62% of cases, according to recent research conducted by the Trans Youth Can team. Many clinics have adopted the policy of offering puberty blockers at a first visit. This is in line with the move to eliminate the need for mental health assessments. 

Are puberty blockers reversible? 

No. Puberty blockers are often touted as reversible, however, there is new and clear evidence that the usage of puberty blockers leads to the usage of cross-sex hormones in 95-98% of cases, with potential surgeries to follow. 

The strength of this relationship is extremely unusual for medical practice.  Since most children who begin puberty blockers move on to cross-sex hormonal treatment, which have irreversible effects, it is difficult to pull apart the effects of puberty blockers alone. Research suggests that puberty blockers, even if followed by cross sex hormones decreases bone density and may have a negative impact on cognitive function. Most clinicians now acknowledge that puberty blockers are not reversible and many believe that being put on a puberty blocker concretizes a trans identity, putting them on a life-long medical pathway. Under the previous “watchful waiting” model in which children were given time and space to mature, the vast majority (68-98%) had their gender dysphoria resolved and they aligned with their biological sex by early adulthood, with most growing up to be LGB. 

Clinicians who use puberty blockers as a first line of treatment (as most do in Canada today) are promoting a belief to their young patients that they are doing something that is good for them. There is a significant amount of trust among Canadians that our medical professionals would only offer or recommend such invasive treatments if they were sure they were in a young person’s best interest.

When did Canada first begin using puberty blockers? 

Usage of puberty blockers in Canada began in 2005, less than 20 years ago. The CAMH GIDS clinic in Toronto was the first clinic to introduce them, under strict cautionary principles and after much assessment and reflection with their young clients to try to determine whether they would be in a young person’s long-term best interest. Parents were an integral part of this decision-making process.

The founder of the CAMH GIDS clinic, Dr Susan Bradley, told us in an interview that the Canadian clinic started using puberty blockers with children who had a long history of gender dysphoria. A young person needed to be 16 before they were even offered puberty blockers. She said that the clinicians really had nothing but a “gut feeling” to go on and that they had adopted the usage of puberty blockers based on the Dutch protocol, which presented puberty blockers as reversible.   

Soon after, medical societies started to produce guidance for the usage of puberty blockers based on the initial Dutch study of 55 young people (this cohort all presented with persistent and consistent early-onset childhood gender dysphoria, unlike many young people seeking gender transition today). So cieties such as the American Academy of Pediatrics and the Endocrine Society endorsed this protocol on the belief that these kids were suicidal and that these interventions were life-saving. At the time, they also believed that puberty blockers were a “pause button” and fully reversible.

Are puberty blockers approved for usage to treat gender dysphoria in minors? 

No. While puberty blocking drugs such as Lupron have been approved and used for precocious puberty (when a child begins to show secondary sex characteristics very early, they have never been approved for treating gender dysphoria in children at a normal age of sexual development, and for a much longer period of time. The usage of puberty blockers for gender dysphoria is “off-label”, meaning that physicians prescribe them based on a hope that they can be effective and that the risks will not outweigh the benefits. There have been no good quality studies of the effects of this treatment. It is highly unlikely that Canadian clinicians are systematically collecting data on the effects of these medications. Such was the case at the Gender Identity Development Services at the Tavistock, the largest gender clinic in the UK, which was ordered to be shut down following numerous issues with an unproven treatment protocol and inadequate collection of data and patient follow-up. 

Approval for usage would require that studies are undertaken to ensure the drugs provide the expected benefits and that the level of risk and side-effects are understood and acceptable. There is a growing body of evidence that the practice of using puberty blockers may be creating harms that are not acceptable. 

What are the side effects of puberty blockers? 

Known side effects of puberty blockers include:



•Mental illness (depression, suicidality, aggression)


•Poor bone growth/Short stature

•Chronic pain

•Potential negative effects on brain development

•Lack of penile length/scrotal tissue for future vaginoplasty

95-98% of children who are treated with puberty blockers go onto cross-sex hormones.

Recently, the British Journal of Medicine published an excellent summary of the current state of research in this area. The weak evidence, the article states: “doesn’t just mean something esoteric about study design, it means there’s uncertainty about whether the long term benefits outweigh the harms”. Canadian health research methods expert, Gordon Guyatt of McMaster University, who co-developed GRADE, a systematic approach to rate the quality and certainty of research evidence, is quoted heavily in this piece. 

How are vulnerable children being protected from harm?

Unfortunately, it’s not clear that vulnerable children are being protected from harm. There seems to be a growing belief system that medical gender transition is simply a reversible “gender journey” (to use a term quoted to us by Sick Kids Hospital). Is it facile to think of treatments that can have permanent changes on a young person’s physical, cognitive and emotional health as a gender journey?

The term “assessment” has been hi-jacked to mean different things. Clinicians within Canadian children’s hospital gender clinics have been quoted in the media saying that “comprehensive assessments” are done before children are started on invasive medical treatments, but that is clearly not the case if puberty blockers are often being initiated at the first visit. The London Gender Pathways Service even created a “consent” form for family physicians to use to initiate puberty blockers BEFORE a first visit to the gender clinic.

A typical assessment today includes a checklist of items that includes questions about medical history. However, clinicians are not given direction about what to do with the information gathered on the checklist. If, for example, a child is autistic, there are no standardized pathways or assessments to determine whether this child has adopted rigid thinking about gender while there are other factors at play. Youth on the ASD spectrum typically have difficulty with self-regulation and don’t feel like they “fit in”, which can lead to depression, anxiety or suicidal thoughts. When such a youth, latches on to the idea that their distress is because they are transgender, their black and white thinking makes it very difficult for them to think more abstractly about sex and gender.  Unfortunately,  when gender becomes a focal point, all else is ignored, not only by the youth, but also by affirming school staff, therapists and physicians.

Canadian autistic children are being put on puberty blockers, cross-sex hormones and have undergone surgeries without being provided appropriate support to understand and manage their mental health issues (and explore how their gender-related distress may be entangled with these other issues). This is also the case for young people who are gay and may be having difficulty understanding or accepting their sexual orientation, those who have suffered a history of trauma such as a sexual assault and for an unexplained and disproportionate number of children living in foster care and identifying as First Nations.  

Perhaps rather than asking whether puberty blockers are reversible, we should be asking some hard questions:

  • Does the initiation of puberty blockers encourage children to undergo unnecessary medical treatments?
  • Does the initiation of puberty blockers hinder the exploration and treatment of underlying mental health issues?
  • Does the initiation of puberty blockers hinder the resolution of gender dysphoria?
  • What evidence is there that puberty blockers support long-term mental and physical well-being?

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