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Detransition research (Vandenbussche, Littman, Boyd)

Detransition — a return to the birth sex after a previously begun medical or surgical transition (Cass Review, para. 15.44; for a social transition alone the Cass Review speaks of desistance) — is a topic on which reliable figures are lacking: those who detransition often do not return to the clinic, and follow-up in studies is too short to capture it (para. 15.50).

Vandenbussche (2021/2022) — a survey of 237 detransitioners

Elie Vandenbussche, a detransitioner herself, published an online survey study in the Journal of Homosexuality (2022; online 2021) among 237 detransitioners recruited from online detrans communities rather than clinics. The sample is self-selected and therefore not representative of all detransitioners. From the figure on reasons for detransitioning in the Cass Review (para. 15.54):

• 70% realised that their gender dysphoria was related to other issues.
• 62% cited health concerns.
• 50% said the transition did not help with their dysphoria.
• 34% said the dysphoria resolved itself over time.

The study is cited in the Cass Review. Vandenbussche continues her work via post-trans.com . An extensive discussion can be found at transitieschade.nl/detrans/onderzoek-vandenbussche .

Littman (2021)

Lisa Littman (2021, Archives of Sexual Behavior) surveyed 100 self-selected detransitioners recruited via social media and mailing lists (source); her sample is not representative of all detransitioners:

• 69% were registered female at birth, 31% male.
• 60% felt more comfortable identifying as their natal sex; 49% had concerns about medical complications; 38% came to believe their dysphoria was caused by something specific, such as trauma, abuse or a mental health condition.
• 55% felt they had not received an adequate evaluation from a doctor or mental health professional before starting transition.
• Only 24% told their clinicians that they had detransitioned.

Boyd (2022), Hall (2021) and Roberts (2022)

Boyd et al. (2022, Healthcare) described a quality-improvement audit in one English multi-site general practice with 68 patients: of the 41 who had started hormones, 8 (20%) stopped after a mean of 5 years, and more than half of those who stopped cited regret or a detransition experience (source; Cass Review, para. 15.51). Hall et al. (2021, BJPsych Open) found 12 cases (6.9%) of detransition in the case notes of 175 service users discharged from a UK adult gender clinic (Cass Review, para. 15.49). Roberts et al. (2022, US Military Health System) found a four-year hormone continuation rate of 70.2% (so 29.8% stopped), higher among those who started as minors; stopping is not the same as regret or detransition (source).

How many detransitioners are there really?

No one knows exactly. According to the Cass Review (para. 15.50), estimates are hard to determine from clinic data: those who detransition often do not return to the clinic, clinicians told the Review that it takes 5 to 10 years before someone detransitions (longer than most follow-up), and the sharp rise in referrals only began in 2014. The figures above (6.9%, 20%, 29.8% stopping) differ greatly in definition and population. For regret after gender-affirming surgery, WPATH cites 0.3-3.8% (SOC8; based on several studies, including the Amsterdam Wiepjes cohort). See also the regret study for the methodological analysis by Bustos 2021.

Voices of detransitioners

Below are some publicly known detransitioners. What they say about their treatment is their own account; in lawsuits these are the plaintiffs' claims, not established facts.

Unknown figures

The Cass Review writes that the percentage of people who detransition after hormone treatment is unknown, because long-term follow-up is lacking (source). The Dutch Health Council also wrote in 2026 that no definitive conclusions can be drawn about the number of cases of regret, because of the often short follow-up and substantial attrition in studies (source). See also Dutch detransitioners — the voices that are not heard .

Irreversible damage that remains

Hormones and surgery have partly irreversible consequences, also for people who later detransition.

• Breast tissue: in a mastectomy, most of the glandular tissue is removed; a reconstruction does not restore the mammary glands. See irreversible loss of breast tissue .
• Fertility: according to the Cass Review, cross-sex hormones may well lead to a loss of fertility; for the effect of puberty blockers on fertility the evidence is insufficient or inconsistent (source). Gonadectomy permanently rules out reproduction. See infertility after hormones and surgery .
• Voice, hair growth, genital surgery: testosterone permanently lowers the voice and causes irreversible beard growth and male pattern baldness. Genital surgery is irreversible. The overview at transitieschade.nl/schade documents thirteen specific categories of damage.

$2 million for detransitioner — US ruling (January 2026)

At the end of January 2026, a jury in White Plains (New York) awarded two million dollars in damages to 22-year-old Fox Varian, who underwent a double mastectomy in 2019 at age 16. She accused her psychologist and her plastic surgeon of failing to inform her adequately about the risks and of deviating from standards of care; the jury sided with her. According to Metro Weekly, it is the first successful medical malpractice lawsuit brought by a detransitioner (source). See the full report .

Vasterman and Kuitenbrouwer: the Dutch Protocol is untenable

Media sociologist Peter Vasterman and journalist Jan Kuitenbrouwer wrote in NRC (28 April 2024) that after the Cass Review the Dutch Protocol is "a medical Titanic heading for an iceberg" (translated) — an experimental treatment of an insufficiently understood condition, in the authors' words. They point out that the patient population (mostly girls with psychological problems) differs strongly from the group for which the protocol was devised, and that there are no studies with an untreated control group. They call for an independent study by the Health Council, an audit of the decision-making process in consultation rooms, and a study of long-term effects based on patient records (source). The Health Council issued advice on transgender care for young people on 30 June 2026 (source). See the full reconstruction at dutchprotocol.nl and the VUmc protocol criticism .

An invisible group

The Cass Review writes that there is a lack of adequate care for people who detransition and who have a range of physical and psychological needs (para. 15.52; source). What hormones or surgery have changed in the body is partly irreversible.