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UK National Institute for Health and Care Excellence and transgender people

by Andrea James Reviewed October 28, 2026 15 min read

The National Institute for Health and Care Excellence (NICE) is a British public body that issues evidence-based guidance on health and social care in England. It is sponsored by the UK Department of Health and Social Care.

In 2020, NHS England commissioned pediatrician Hilary Cass to chair a policy working group yo review the evidence on puberty blockers and cross-sex hormones for trans and gender diverse young people, and whether its clinical policies on them should change. NHS England also asked NICE to develop guidance on when to refer children to specialist services. Cass was later appointed to lead the Cass Review, an independent review of gender identity services for children and young people. NHS England also commissioned NICE to review the evidence on puberty blockers and cross-sex hormones for trans and gender diverse minors. The reviews were commissioned to inform Cass’s working group. They influenced the Cass Review and NHS England’s subsequent restrictions on these treatments.

The NICE reviews were commissioned and published using undisclosed participants. NICE has refused Freedom of Information requests seeking the names of those involved. The production and dissemination of the NICE reports have significant ties to anti-trans hate group Society for Evidence-Based Gender Medicine (SEGM). Over one-third of the authors who have promoted the reports are SEGM members or conference speakers. In June 2023, members of the Cass Review team diclosed to Trans Safety Network that 2025 SEGM conference speaker Az Hakeem, was part of NHS England’s policy working group which commissioned the NICE evidence reviews.

Background

NICE was set up in 1999 as the National Institute for Clinical Excellence. The Health and Social Care Act 2012 made it an England-only executive non-departmental public body from April 2013, and extended its remit to adults’ and children’s social care. NICE produces clinical guidelines, technology appraisals of medicines and devices, and evidence reviews.

2020 evidence reviews on hormones for trans minors

In January 2020, NHS England set up an independent policy working group, chaired by pediatrician Hilary Cass, to review the evidence on puberty blockers and cross-sex hormones for trans and gender diverse youth. It also commissioned NICE to review the published research for the group. In September 2020, NHS England expanded Cass’s role. Cass was commissioned to lead the Independent Review of Gender Identity Services for Children and Young People (aka the Cass Review). NICE completed its two evidence reviews in October 2020. Weeks later, in December 2020, the High Court ruled in Bell v. Tavistock that under-16s were unlikely to be able to consent to puberty blockers. The reviews were released quietly on NICE’s evidence website in March 2021, rated nearly all the evidence “very low” certainty, and drew wide attention after the BBC reported them on April 1. They later fed into the Cass Review’s interim and final reports and into NHS England’s 2024 decision to end routine prescribing of puberty blockers.

Puberty blocker evidence review

For this report, NICE looked at just nine observational studies:

  • Brik T, Vrouenraets LJJJ, de Vries MC, Hannema SE (2020). Trajectories of adolescents treated with gonadotropin-releasing hormone analogues for gender dysphoria. Archives of Sexual Behavior 49(7):2611–2618. https://doi.org/10.1007/s10508-020-01660-8
  • Costa R, Dunsford M, Skagerberg E, Holt V, Carmichael P, Colizzi M (2015). Psychological support, puberty suppression, and psychosocial functioning in adolescents with gender dysphoria. Journal of Sexual Medicine 12(11):2206–2214. https://doi.org/10.1111/jsm.13034
  • de Vries ALC, Steensma TD, Doreleijers TAH, Cohen-Kettenis PT (2011). Puberty suppression in adolescents with gender identity disorder: a prospective follow-up study. Journal of Sexual Medicine 8(8):2276–2283. https://doi.org/10.1111/j.1743-6109.2010.01943.x
  • Joseph T, Ting J, Butler G (2019). The effect of GnRH analogue treatment on bone mineral density in young adolescents with gender dysphoria: findings from a large national cohort. Journal of Pediatric Endocrinology and Metabolism 32(10):1077–1081. https://doi.org/10.1515/jpem-2019-0046
  • Khatchadourian K, Amed S, Metzger DL (2014). Clinical management of youth with gender dysphoria in Vancouver. Journal of Pediatrics 164(4):906–911. https://doi.org/10.1016/j.jpeds.2013.10.068
  • Klink D, Caris M, Heijboer A, van Trotsenburg M, Rotteveel J (2015). Bone mass in young adulthood following gonadotropin-releasing hormone analog treatment and cross-sex hormone treatment in adolescents with gender dysphoria. Journal of Clinical Endocrinology & Metabolism 100(2):E270–E275. https://doi.org/10.1210/jc.2014-2439
  • Schagen SEE, Cohen-Kettenis PT, Delemarre-van de Waal HA, Hannema SE (2016). Efficacy and safety of gonadotropin-releasing hormone agonist treatment to suppress puberty in gender dysphoric adolescents. Journal of Sexual Medicine 13(7):1125–1132. https://doi.org/10.1016/j.jsxm.2016.05.004
  • Staphorsius AS, Kreukels BPC, Cohen-Kettenis PT, Veltman DJ, Burke SM, Schagen SEE, Wouters FM, Delemarre-van de Waal HA, Bakker J (2015). Puberty suppression and executive functioning: an fMRI-study in adolescents with gender dysphoria. Psychoneuroendocrinology 56:190–199. https://doi.org/10.1016/j.psyneuen.2015.03.007
  • Vlot MC, Klink DT, den Heijer M, Blankenstein MA, Rotteveel J, Heijboer AC (2017). Effect of pubertal suppression and cross-sex hormone therapy on bone turnover markers and bone mineral apparent density (BMAD) in transgender adolescents. Bone 95:11–19. https://doi.org/10.1016/j.bone.2016.11.008

Hormone evidence review

For this report, NICE looked at just ten observational studies:

Effectiveness:

  • Achille C, Taggart T, Eaton NR, Osipoff J, Tafuri K, Lane A, Wilson TA. (2020). Longitudinal impact of gender-affirming endocrine intervention on the mental health and well-being of transgender youths: preliminary results. International Journal of Pediatric Endocrinology, 2020, 8. https://doi.org/10.1186/s13633-020-00078-2
  • Allen LR, Watson LB, Egan AM, Moser CN. (2019). Well-being and suicidality among transgender youth after gender-affirming hormones. Clinical Practice in Pediatric Psychology, 7(3), 302–311. https://doi.org/10.1037/cpp0000288
  • Kaltiala R, Heino E, Työläjärvi M, Suomalainen L. (2020). Adolescent development and psychosocial functioning after starting cross-sex hormones for gender dysphoria. Nordic Journal of Psychiatry, 74(3), 213–219. https://doi.org/10.1080/08039488.2019.1691260
  • Kuper LE, Stewart S, Preston S, Lau M, Lopez X. (2020). Body dissatisfaction and mental health outcomes of youth on gender-affirming hormone therapy. Pediatrics, 145(4), e20193006. https://doi.org/10.1542/peds.2019-3006
  • López de Lara, D., Pérez Rodríguez, O., Cuellar Flores, I., Pedreira Masa, J. L., Campos-Muñoz, L., Cuesta Hernández, M., & Ramos Amador, J. T. (2020). Psychosocial assessment in transgender adolescents. Anales de Pediatría (English Edition), 93(1), 41–48. https://doi.org/10.1016/j.anpede.2020.01.004

Safety (bone density, cardiovascular risk, adverse events):

  • Khatchadourian K, Amed S, Metzger DL. (2014). Clinical management of youth with gender dysphoria in Vancouver. The Journal of Pediatrics, 164(4), 906–911. https://doi.org/10.1016/j.jpeds.2013.10.068
  • Klaver M, de Mutsert R, van der Loos MATC, Wiepjes CM, Twisk JWR, den Heijer M, Rotteveel J, Klink DT. (2020). Hormonal treatment and cardiovascular risk profile in transgender adolescents. Pediatrics, 145(3), e20190741. https://doi.org/10.1542/peds.2019-0741
  • Klink D, Caris M, Heijboer A, van Trotsenburg M, Rotteveel J. (2015). Bone mass in young adulthood following gonadotropin-releasing hormone analog treatment and cross-sex hormone treatment in adolescents with gender dysphoria. The Journal of Clinical Endocrinology & Metabolism, 100(2), E270–E275. https://doi.org/10.1210/jc.2014-2439
  • Stoffers IE, de Vries MC, Hannema SE. (2019). Physical changes, laboratory parameters, and bone mineral density during testosterone treatment in adolescents with gender dysphoria. The Journal of Sexual Medicine, 16(9), 1459–1468. https://doi.org/10.1016/j.jsxm.2019.06.014
  • Vlot MC, Klink DT, den Heijer M, Blankenstein MA, Rotteveel J, Heijboer AC. (2017). Effect of pubertal suppression and cross-sex hormone therapy on bone turnover markers and bone mineral apparent density (BMAD) in transgender adolescents. Bone, 95, 11–19. https://doi.org/10.1016/j.bone.2016.11.008

NICE findings

NICE rated the evidence on its critical outcomes (gender dysphoria, mental health and quality of life) as very low certainty, using a modified GRADE approach. It said all the included studies were small and uncontrolled, and therefore open to bias and confounding. It also said it found no cost-effectiveness evidence.

Neither review made recommendations. Both were advice prepared for NHS England, not formal NICE guidance. The subsequent policy decisions were NHS England’s.

Puberty blocker review

NICE looked at nine small observational studies with no control groups: five retrospective, three prospective and one cross-sectional. It rated the evidence on its critical outcomes (gender dysphoria, mental health and quality of life) as very low certainty, and said the studies suggested little change from starting blockers to follow-up. It found no evidence at all on quality of life. NICE acknowledged that “no change” might itself be the treatment’s effect, since without blockers, distress might be expected to rise as puberty progressed. It also noted that one study (de Vries et al. 2011) found statistically significant improvements on behavioural and emotional checklists, which could be important because those scales partly measure distress. On bone density, NICE said blockers may reduce the increase normally expected during puberty, but without comparison groups it couldn’t tell whether the changes were caused by the treatment. It rated all safety evidence very low certainty, found no evidence on cost-effectiveness, and said outcomes may differ between trans girls and trans boys. NICE accepted that controlled trials may not be possible, but said comparative studies were needed.

Hormone review

NICE looked at ten small observational studies with no control groups. Five reported on effectiveness, and NICE said they suggested hormones are likely to improve gender dysphoria and may also improve depression, anxiety, quality of life, suicidality and psychosocial functioning; the effect on body image was unclear. All these results were rated very low certainty, and NICE said their clinical relevance was hard to judge, because most outcomes have no agreed minimum meaningful change and some studies reported no statistical analysis. The other five studies reported on safety. They showed some increases in bone density after hormones were started, varying by body site and by group, though bone density stayed lower than in comparable cisgender young people. One study found higher blood pressure and body mass index at age 22, and a worse cholesterol profile in trans boys. Only one study reported side effects or how many people stopped treatment, so NICE drew no conclusions on those. It said any benefits had to be weighed against a largely unknown long-term safety profile.

Dissemination

The NICE reports were quietly published in March 2021 and did not receive much attention until BBC News covered them in early April.

The NICE reports were promoted in the following outlets, most of which are known vectors for anti-trans output:

Named authors promoting the NICE reviews include:

Psychiatrist Az Hakeem, who was reportedly part of NHS England’s policy working group, has close ties to anti-trans hate group Society for Evidence-Based Gender Medicine (SEGM). Abbruzzese, Athéa, Banaschewski, “J. Cohn,” Jorgensen, Kingdon, Kulatunga-Moruzi, Landén, Levine, Masson, McDeavitt, and Zepf are all associated with SEGM as members or conference speakers.

Criticism

Critics of the NICE reports have discussed the problems with their clinical framing and inclusion criteria.

Puberty blockers are meant to stop unwanted pubertal changes. They aren’t intended to relieve gender distress on their own, which is also affected by prejudice, family conflict, bullying, and barriers to care. Judging blockers on whether they reduce “dysphoria” therefore set them up to fail. That said, the reviews’ finding of “stasis” on mental health rather than worsening could itself be a good result.

The reviews included only primary clinical studies and excluded much of the literature. In an extensive analysis, physician AJ Eckert identifies a dozen studies the puberty blocker review omitted or excluded, disputes NICE’s stated reasons for several, and cites further research supporting the treatments’ safety and benefits.

Impact

The NICE reviews have negatively impacted access to trans healthcare in the United Kingdom and beyond.

United Kingdom

The NICE reviews became the evidence base for a series of NHS England and UK government decisions. The Cass Review’s interim report (February 2022) built on them. The Cass Review also commissioned the University of York to carry out a wider research program that built on NICE’s appraisal, and the final report (April 2024) drew on both. In October 2022, NHS England’s interim service specification said puberty blockers would be offered only in research settings. In May 2023, NHS England ran a literature surveillance check against the NICE puberty blocker review. It found two newer studies that might materially affect its conclusions, but its clinical panel decided they didn’t change the overall picture. NHS England’s March 2024 clinical policy ended routine prescribing of puberty blockers from April 1, 2024, citing the NICE review together with later evidence. A separate policy that month set new conditions for cross-sex hormones. The UK government then restricted puberty blockers from private prescribers. Its December 2024 document making that ban indefinite cites NICE’s findings that blockers had no statistically significant effect on gender dysphoria, mental health, body image or psychosocial functioning. In 2025–26, NHS England commissioned a further hormone review covering research published since NICE’s, and paused new hormone prescriptions for 16- and 17-year-olds.

In a joint October 2023 statement responding to NHS England’s puberty blocker consultation, the European and World Professional Associations for Transgender Health (EPATH and WPATH) argued that the NICE review’s narrow inclusion criteria left out relevant studies.

Sweden

In April 2021, weeks after the reviews were published, Karolinska University Hospital in Stockholm issued a guideline restricting puberty blockers and cross-sex hormones for minors to research settings or exceptional cases. The guideline lists both NICE reviews among its sources. SEGM quickly translated and disseminated the Karolinska documents.

Germany

In 2024, a team of German child and adolescent psychiatrists led by Florian Zepf published an updated systematic review titled “Beyond NICE.” It extended NICE’s analysis with newer studies and reached similar conclusions about the evidence. Zepf had stepped down from the Austrian, Swiss, and German participants in developing a joint S2k guideline on trans healthcare for young people. That guideline recommended a strct gatekeeping model over the objections of the “Beyond NICE” authors. The German goverment imposed no ban or legal restriction.

New Zealand

NICE was among the overseas reviews cited in public pressure on New Zealand’s Ministry of Health, including an April 2023 New Zealand Herald opinion piece by Jan Rivers. The ministry published its own evidence brief in November 2024. It found the evidence on puberty blockers limited and of poor quality, and the government paused new prescriptions in November 2025.

United States

In addition to the coverage in American academic and lay publications listed above, the NICE reviews were cited in the 2025 Trump Administration US HHS report created as a pretext for banning trans healthcare for minors.

References

Moore, Mallory (March 28, 2024). Trans Safety Network statement on NICE evidence reviews on trans affirming care. Trans Safety Network https://transsafety.network/posts/statement-on-nhs-gd-wg/

Maung, H. H. (2024). Gender Affirming Hormone Treatment for Trans Adolescents: A Four Principles Analysis. Journal of Bioethical Inquiry, 21(2), 345–363. https://doi.org/10.1007/s11673-023-10313-z

Wilson, Luci et al (October 27, 2023). URGENT: The Puberty Blockers Consultation Advice. What the Trans https://whatthetrans.com/puberty-blockers-consultation-advice/

Horton, C. (June 4, 2022). “I Didn’t Want Him to Disappear” Parental Decision-Making on Access to Puberty Blockers for Trans Early Adolescents. The Journal of Early Adolescence, 43(4), 490–515. https://doi.org/10.1177/02724316221107076

Horton, Cal (July 13, 2022). Evidence-based medicine: what do we mean by ‘low quality’ evidence in trans healthcare? Growing Up Transgender https://growinguptransgender.com/2022/07/13/evidence-based-medicine-what-do-we-mean-by-low-quality-evidence-in-trans-healthcare/

Eckert, AJ (October 17, 2021). Conclusions not so NICE: a critical analysis of the NICE evidence review of puberty blockers for children and adolescents with gender dysphoria. Science-Based Medicine https://sciencebasedmedicine.org/a-critical-look-at-the-nice-review/

Staff report (April 3, 2021). Puberty blockers: does NICE review ask the right questions? GenderGP https://www.gendergp.com/blog/puberty-blockers-does-nice-review-ask-the-right-questions/

Anti-trans coverage

Kingdon C, Stingelin-Giles N, Cass H. (2025). The Cass Review: distinguishing fact from fiction. The American Journal of Bioethics. https://doi.org/10.1080/15265161.2025.2504397

McDeavitt, K., “Cohn, J.,” & Kulatunga-Moruzi, C. (2025). Pediatric Gender Affirming Care is Not Evidence-based. Current Sexual Health Reports, 17(1). https://doi.org/10.1007/s11930-025-00404-w

McDeavitt, K., “Cohn, J.,” & Levine, S. B. (2025). Critiques of the Cass Review: Fact-Checking the Peer-Reviewed and Grey Literature. Journal of Sex & Marital Therapy, 51(2), 175–199. https://doi.org/10.1080/0092623x.2025.2455133

Defant, M. J. (2025). Reevaluating gender-affirming care: biological foundations, ethical dilemmas, and the complexities of gender dysphoria. Journal of Sex & Marital Therapy, 51(2), 200–210. https://doi.org/10.1080/0092623x.2025.2456066

Cheung, C. R., Abbruzzese, E., Lockhart, E., Maconochie, I. K., & Kingdon, C. C. (2024). Gender medicine and the Cass Review: why medicine and the law make poor bedfellows. Archives of Disease in Childhood, 110(4), 251–255. https://doi.org/10.1136/archdischild-2024-327994

Zepf, F. D., König, L., Kaiser, A., Ligges, C., Ligges, M., Roessner, V., Banaschewski, T., & Holtmann, M. (2024). Beyond NICE: Aktualisierte systematische Übersicht zur Evidenzlage der Pubertätsblockade und Hormongabe bei Minderjährigen mit Geschlechtsdysphorie [Beyond NICE: Updated Systematic Review on the Current Evidence of Using Puberty Blocking Pharmacological Agents and Cross-Sex-Hormones in Minors with Gender Dysphoria]. Zeitschrift für Kinder- und Jugendpsychiatrie und Psychotherapie, 52(3), 167–187. https://doi.org/10.1024/1422-4917/a000972

Jorgensen, S. C. J., Athéa, N., & Masson, C. (2024). Puberty Suppression for Pediatric Gender Dysphoria and the Child’s Right to an Open Future. Archives of Sexual Behavior, 53(5), 1941–1956. https://doi.org/10.1007/s10508-024-02850-4

McPherson, S., & Freedman, D. E. P. (2023). Psychological Outcomes of 12–15-Year-Olds with Gender Dysphoria Receiving Pubertal Suppression in the UK: Assessing Reliable and Clinically Significant Change. Journal of Sex & Marital Therapy, 50(3), 315–325. https://doi.org/10.1080/0092623x.2023.2281986

Levine, S. B., & Abbruzzese, E. (2023). Current Concerns About Gender-Affirming Therapy in Adolescents. Current Sexual Health Reports, 15(2), 113–123. https://doi.org/10.1007/s11930-023-00358-x

Ludvigsson, J. F., Adolfsson, J., Höistad, M., Rydelius, P., Kriström, B., & Landén, M. (2023). A systematic review of hormone treatment for children with gender dysphoria and recommendations for research. Acta Paediatrica, 112(11), 2279–2292. https://doi.org/10.1111/apa.16791

Staff report (June 11, 2022). On medical interventions for gender dysphoria. Clinical Advisory Network on Sex and Gender https://can-sg.org/academic-papers/on-medical-interventions-for-gender-dysphoria/

Staff report (April 14, 2021). Evidence for puberty blockers use very low, says NICE – BBC News. Feminist Legal Clinic https://feministlegal.org/evidence-for-puberty-blockers-use-very-low-says-nice-bbc-news/

Showalter, Brandon (April 8, 2021). Evidence for puberty blockers, cross-sex hormones as effective treatment ‘very low’: NHS England. The Christian Post https://www.christianpost.com/news/evidence-for-puberty-blockers-as-effective-treatment-very-low.html

Staff report (April 2, 2021). NICE review echoes concerns raised by experts: poor evidence base for puberty blockers and cross-sex hormones. Bayswater Support Group https://www.bayswatersupport.org.uk/nice-review-echoes-concerns-raised-by-experts-poor-evidence-base-for-puberty-blockers-and-cross-sex-hormones/

Smith, Wesley J. (April 1, 2021). ‘Very low’ evidence for blocking puberty of gender-dysphoric children. National Review https://www.nationalreview.com/corner/very-low-evidence-for-blocking-puberty-of-gender-dysphoric-children/

Staff report (April 1, 2021). Evidence for puberty blockers use very low, says NICE. BBC News https://www.bbc.co.uk/news/health-56601386

Staff report (March 31, 2021). New systematic reviews of puberty blockers and cross-sex hormones published by NICE. Society for Evidence-Based Gender Medicine https://segm.org/NICE_gender_medicine_systematic_review_finds_poor_quality_evidence

Resources

NICE (nice.org.uk)

  • Puberty blocker report
  • england.nhs.uk/wp-content/uploads/2024/03/evidence-review-gnrh-analogues-october-2020.pdf
  • original url arms.nice.org.uk/resources/hub/1070871/attachment [archive]
  • original url arms.nice.org.uk/resources/hub/1070905/attachment [archive]
  • Hormone report
  • webarchive.nationalarchives.gov.uk/ukgwa/20250310143633/https://cass.independent-review.uk/wp-content/uploads/2022/09/20220726_Evidence-review_Gender-affirming-hormones_For-upload_Final.pdf

Facebook (facebook.com)

X/Twitter (x.com)

YouTube (https://www.youtube.com/user/NICEmedia)

  • niceorguk
  • original url youtube.com/user/NICEmedia

LinkedIn (linkedin.com)

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