Claim 1: “Puberty blockers have serious, irreversible side-effects.” ¹

Claim 2: “Puberty blockers cause permanent bone damage, IQ loss, brain swelling, and multiple fatalities.” ²

Claim 3: “The FDA issued a black-box warning on puberty blockers because they're dangerous.” ³

Claim 4: “The Cass Review and/or HHS Report prove/is evidence that puberty blockers harm children.” ⁴

Any claim suggesting:

• Puberty blockers are irreversible
• They cause irreversible harm to bone density
• They lower IQ permanently
• Multiple deaths have resulted from brain swelling
• The FDA issued the most serious type of warning
• Government reviews have documented net harm from puberty blockers

All of these claims rely on the same misrepresentations of evidence, selective interpretation of studies, and conflation of different populations. We'll break down how each claim distorts the actual research.

The correct terminology matters:

Puberty blockers are medications that pause the physical changes of puberty. The most commonly used are gonadotropin-releasing hormone (GnRH) agonists, which temporarily suppress sex hormone production. ⁵

Anti-trans advocates frequently state that puberty blockers cause “serious, irreversible side-effects.”

Reversibility is established medical fact:

“When puberty blockers are discontinued, pubertal development resumes naturally. Once the patients receive gender-affirming hormones or decide to go off blockers and go through an endogenous puberty, their bone density increases.” ⁶

The mechanism is straightforward:

“When a person stops taking this medication, their body produces their natural hormones again, resulting in the development of breasts, facial hair, a deeper voice, and menstruation.” ⁷

This is not a new or controversial finding. Puberty blockers have been used safely in cisgender children for decades: “For decades, puberty blockers have been prescribed to cisgender kids experiencing precocious puberty as well as to transgender youths with knowledge about potential bone density issues. Parents are advised to bolster bone health with vitamin D, calcium and exercise.” ⁸

The claim rests on equivocation. When activists say “irreversible,” they're conflating:

1. The medication's effects (which are reversible)
2. Time lost during development (which is not recoverable)

These are different problems. A 14-year-old on puberty blockers for two years cannot get those two years back—but their puberty can resume normally when treatment stops.

“Puberty blockers cause irrevocable harm to bone density that is never resolved.”

During treatment: Bone density growth slows. This is documented.

After treatment stops: “Bone mineral density values improve once individuals stop taking puberty-delaying medication or start gender-affirming hormones.” ⁹

For youth on gender-affirming hormones: “Treatment with GnRH agonists followed by long-term GAH is safe with regard to bone health in transgender persons.” ¹⁰

The actual picture is more nuanced:

“A longer duration of treatment with puberty-delaying medications among transgender youth is associated with lower bone mineral density.” ¹¹

This is why careful monitoring and duration limits matter—not because the effect is irreversible, but because recovery is slower with longer suppression.

Critics cite studies showing that “not all patients fully rebound,” then extrapolate to “never recover.” The evidence actually shows:

1. Most patients recover bone density when treatment stops or hormones begin
2. Some patients may not fully return to pre-suppression levels
3. This is managed through vitamin D, calcium, and exercise
4. It's comparable to other pediatric conditions requiring monitoring

This is medical management, not proof of irreversible harm.

“Studies show puberty blockers lower IQ by 7-9 points.”

Critical population distinction:

“Only five studies have specifically looked at the impact of puberty blockers on cognitive development in young people. Two of these studies looked at the effects in children with precocious puberty and three looked at the effects in children who had been prescribed puberty blockers for gender dysphoria.” ¹²

The IQ studies cited are from precocious puberty populations, not transgender youth. ¹³

What studies on transgender youth actually show:

“This may reflect that gender-affirming medical treatment including puberty suppression does not negatively affect the association between IQ and educational achievement.” ¹⁴

“Current evidence does not suggest any negative impact on cognitive development, IQ, or fertility.” ¹⁵

Studies showing 7-9 point IQ drops come from children treated for genuinely precocious puberty—a different population with different starting ages, treatment durations, and underlying conditions.

You cannot use data from population A to claim outcomes for population B without evidence specific to population B.

“Puberty blockers have caused multiple fatalities from brain swelling (pseudotumor cerebri).”

The actual numbers:

“The FDA identified 6 cases in females ages 5-12 years old who were diagnosed with pseudotumor cerebri.” ¹⁶

Note: This is 6 cases total, primarily in children with precocious puberty. No fatalities are documented in any official FDA statement. ¹⁷

The actual warning:

The FDA added a warning to the labeling—not a black-box warning. This is an important distinction: ¹⁸

1. Black-box warning: The FDA's most serious warning level, reserved for extremely dangerous drugs
2. Labeling warning: A safety alert added to prescribing information, recommending monitoring

“The new warning includes recommendations to monitor patients taking GnRH agonists for signs and symptoms of pseudotumor cerebri, including headache, papilledema, blurred or loss of vision.” ¹⁹

This is appropriate medical monitoring, not evidence of mass harm.

“Evidence shows puberty blockers harm more children than they help.”

Documented harms:

1. 6 cases of pseudotumor cerebri (treatable with monitoring)
2. Temporary bone density reduction (recoverable)
3. No documented fatalities
4. No documented permanent IQ effects in transgender youth

The ratio is not even close. The evidence overwhelmingly supports net benefit.

“Puberty blockers should not be prescribed until we have completely conclusive evidence of safety and benefit.”

This is an asymmetrical standard applied only to gender-affirming care.

The same people making this claim do not demand:

1. Conclusive evidence that withholding puberty blockers is safe
2. Conclusive evidence that conversion therapy is harmful (though it is ²⁵)
3. Conclusive evidence before prescribing other psychiatric medications to trans youth

What happens when puberty blockers are withheld:

“Transgender and non-binary youth who didn't begin hormones or puberty blockers within the first three to six months of starting care demonstrated a two- to three-fold increase in depression and suicidality.” ²⁶

The evidence-based choice is clear: Providing access to puberty blockers has documented mental health benefits and documented manageable risks. Withholding access has documented harms.

“The Cass Review and HHS Report document serious harms from puberty blockers, proving they shouldn't be prescribed.”

Critical distinction: Both reports recommend caution and more research—they do not document net harm or prove that puberty blockers harm children.

What it actually recommends:

The Cass Review recommended “cautious use of hormonal interventions” and more research protocols—it did not document net harm or show that “more children are harmed.” ²⁷

What critics found:

- Methodological flaws: A peer-reviewed 2025 analysis identified “methodological flaws and unsubstantiated claims” and found “a double standard in the quality of evidence.” ²⁸

- Failed to follow evidence standards: Yale Law School's comprehensive critique concluded the report “does not follow established standards for evaluating evidence and evidence quality.” ²⁹

- Rejected mental health evidence: The report outright rejected all studies based on mental health outcomes—which means it deliberately excluded the evidence showing benefits. ³⁰

- Contradicted existing evidence: “Although the existing literature reports a wide range of important benefits of social transition and no credible evidence of harm, the Cass Review cautions against it.” ³¹

- Harm to patients: Researchers from 15 Australian pediatric care institutions stated they were “gravely concerned” about the well-being of trans and gender-diverse people following the Cass Review's influence. ³²

Critical point: Recommending caution ≠ proving harm exists.

Key issues:

- Political document, not scientific review: The report was commissioned by an executive order titled “Protecting Children from Chemical and Surgical Mutilation”—which makes the predetermined political conclusion obvious. ³³

- Packed with anti-trans activists: When authors were finally revealed, they turned out to be known anti-trans activists—not all of whom are even doctors or researchers. ³⁴ You don't get scientific credibility by packing a panel with ideologically aligned activists. That's not peer review; that's advocacy.

- No new evidence of harm: The report describes transition-related care as “too readily available,” yet more than 50% of U.S. states have already banned it. ³⁵ If it were causing mass harm, there would be widespread reporting and litigation; instead, the restriction is political.

- Mirrors Cass Review: The HHS report follows the same pattern as Cass—it “mirrors the Cass Review in tone and form,” suggesting it was designed with a predetermined conclusion. ³⁶

Critical point: An agenda-driven government report with hidden authorship is not evidence of harm.

You can read the initial analysis I wrote about it here

Evidence would require:

• Documented adverse outcomes in large populations
• Causation demonstrated (not just correlation)
• Comparison to control groups (what happens without care)
• Peer-reviewed publication in mainstream journals
• Independent verification by researchers without political agenda

What we have instead:

• Meta-analyses showing benefits (reduced suicidality, depression, anxiety)
• Randomized controlled trials showing safety
• Major medical organizations supporting care based on evidence
• Two government reviews making recommendations for caution, not proving harm exists

What transphobes demand:

1. Absolute proof that puberty blockers help (which exists)
2. But simultaneously, they claim Cass and HHS prove harm, even though these reports:
3. Don't document net harm
4. Recommended research, not bans
5. Explicitly contradicted existing evidence
6. Were subject to methodological critique or political bias

What they ignore:

• Evidence that withholding care causes demonstrable harm (2-3x increase in depression/suicidality) ³⁷
• That major medical organizations—based on actual evidence review—support gender-affirming care
• That both the Cass Review and HHS report faced serious academic and professional critique

“Puberty blockers are a safe and reversible option to give TGD youth the time they need to explore their gender identity.” ³⁸

“Gender-affirming care improves the mental health and overall well-being of gender diverse children and adolescents.” ³⁹

All major medical organizations support puberty blockers as part of gender-affirming care:

1. World Professional Association for Transgender Health (WPATH)
2. American Medical Association
3. American Academy of Pediatrics
4. Endocrine Society
5. American Psychological Association

When claims are examined carefully, the evidence does not support the opposition narrative. Puberty blockers are:

1. Reversible (effects resume normal puberty when stopped)
2. Safe (used safely for decades in other populations)
3. Beneficial (documented mental health improvements)
4. Monitored (regular medical supervision recommended)

The evidence, consistently cited across peer-reviewed research and endorsed by major medical organizations, indicates that puberty blockers are an appropriate medical option for transgender youth experiencing gender dysphoria.