askST: What is chemical castration? How does it work as a method to combat sex crimes?

Chemical castration is a more temporary form of treatment, compared to surgical methods.

Published Sep 09, 2026, 01:20 PM

Updated Sep 09, 2026, 01:20 PM

SINGAPORE - Chemical castrations may be considered in Singapore if there is evidence showing they are effective in bringing down crime rates, said Home Affairs Minister K. Shanmugam in a written response to a parliamentary question on Sept 8, as cases of sexual assault here are on the rise .

Here’s what to know about the procedure that has been used as both punishment and a form of treatment:

What is chemical castration?

Chemical castration is a drugs-based method used to reduce sex hormones, namely androgens like testosterone, to suppress libidos or sex drives.

It is a more temporary form of castration, in contrast with the permanent form of surgical castration.

Other names used to refer to chemical castration include hormone therapy, or androgen suppression therapy.

Anti-androgen medications can be injected under the skin to block hormone production in the testicles, where about 95 per cent of androgens including testosterone and dihydrotestosterone are made, according to Stanford University’s school of medicine.

The injections, which can be applied at the abdomen or buttocks, are not a one-time treatment and must be repeated for the effect to continue, with normal hormone production generally returning after treatment ceases .

Another method involves implants placed under the skin of the arm, back or neck to continuously release the hormone-suppressing medication.

Anti-androgen pills can also be taken orally to block the body’s ability to absorb male hormones.

What is the science behind it?

Chemical castration involves taking medications called LHRH (luteinising hormone-releasing hormones) or GnRH (gonadotropin-releasing hormones) agonists.

By taking the agonists, the pituitary gland reduces production of the hormones which normally send signals to the testicles to produce androgens.

This leads to an effect similar to surgical castration.

Chemical castration is also used as a medical treatment for some prostate and breast cancers that feed on sex hormones, according to Johns Hopkins University’s researchers.

Which Asian countries use it as a legal punishment?

In 2011, South Korea became the first country in Asia to use chemical castration on convicted paedophiles, with the period for its use capped at 15 years . The law was later expanded against sex offenders like attempted rapists or those whose sexual crimes lead to injury or the death of minors aged below 19.

Indonesia followed in 2020, when then-president Joko Widodo signed a regulation that perpetrators of sexual violence against children under the age of 18 will also face chemical castration for a period up to two years.

In Thailand, chemical castration is voluntary, with offenders consenting to receive the treatment after evaluations by a psychiatrist and internal medicine specialist. The law, which came into effect in 2023, allows sex offenders to get an early release from prison in exchange for a hormone-blocking injection to reduce sexual urges.

Where else in the world allows chemical castration?

In the United States, several states including California, Texas, Alabama and Florida implement chemical castration laws for repeat or severe sex offenders. In Europe, countries like Britain, Denmark and Germany offer voluntary chemical castration programmes, whereas it is a mandatory sentence in other countries like Poland and Russia.

What are the arguments and evidence for and against chemical castration?

The short answer for the effectiveness of chemical castration cannot be determined, said Paul Cheong, senior law lecturer at the Singapore University of Social Sciences’ School of Law, writing in the Singapore Law Gazette.

He pointed to the lack of consensus of when it should be triggered, who should bear the costs of treatment and monitoring, and the possibility of sex offeners abusing other drugs to counter those used for chemical castration.

“The cacophony of voices screaming for chemical castration is muted by the deafening silence of medical and legal literature,” he said.

Others also point to the ethical concerns involved, with doctors in Indonesia refusing to implement chemical castration when the law was introduced and human rights researchers in the country calling the procedure “inhumane” and a “degrading” form of punishment.

Advocates for chemical castration point to its reversible nature, and a higher drop in recidivism in voluntary programmes where the offender consents to drug treatment alongside other procedures such as therapy.

For instance in England, hormone-suppressing drugs are taken along with other forms of psychiatric treatment that targets other causes of sexual offending, such as a desire for power and control.

In South Korea, a study by the Korean Institute of Criminology and Justice involving offenders who received hormonal drug treatments showed an overall reduction of sex offence recidivism by 92 per cent.

But officials have pointed to the high costs required to keep up the treatment, with an estimated 5 million won (S$4,720) per offender a year cited. The need for continued treatment was highlighted by a study noting offenders experienced an unexpected upsurge of testosterone levels with intense sexual drive and fantasy during the first two months after treatment cessation.

Singapore Parliament

与外科手术方法相比，化学阉割是一种更暂时的治疗方法。

发布于 2026 年 9 月 9 日下午 1:20

更新于2026年9月9日下午1:20

新加坡——内政部长尚穆根在9月8日对议会质询的书面答复中表示，如果证据表明化学阉割能够有效降低犯罪率，新加坡可以考虑采用化学阉割，因为新加坡的性侵犯案件正在增加。

以下是关于这种既被用作惩罚手段又被用作治疗手段的程序需要了解的内容：

什么是化学阉割？

化学阉割是一种利用药物来降低性激素（即睾酮等雄激素）水平，从而抑制性欲或性冲动的方法。

与永久性的外科阉割相比，这是一种暂时性的阉割方式。

化学阉割的其他名称包括激素疗法或雄激素抑制疗法。

斯坦福大学医学院表示，抗雄激素药物可以注射到皮下，以阻止睾丸中激素的产生，睾丸是人体产生约 95% 的雄激素（包括睾酮和二氢睾酮）的地方。

注射疗法可以应用于腹部或臀部，并非一次性治疗，必须重复进行才能保持疗效，治疗停止后，正常的激素分泌通常会恢复。

另一种方法是在手臂、背部或颈部的皮肤下植入植入物，以持续释放抑制激素的药物。

抗雄激素药片也可以口服，以阻止身体吸收雄性激素。

它背后的科学原理是什么？

化学阉割包括服用称为 LHRH（促黄体生成素释放激素）或 GnRH（促性腺激素释放激素）激动剂的药物。

服用激动剂后，垂体会减少通常向睾丸发出信号以产生雄激素的激素的产生。

这会产生类似于外科阉割的效果。

约翰·霍普金斯大学的研究人员表示，化学阉割也被用作治疗某些以性激素为食的前列腺癌和乳腺癌的医疗手段。

哪些亚洲国家将其作为一项法律刑罚？

2011年，韩国成为亚洲第一个对恋童癖罪犯使用化学阉割的国家，使用期限最长为15年。后来，该法律的适用范围扩大到性犯罪者，例如强奸未遂者或性犯罪导致19岁以下未成年人受伤或死亡的人。

2020 年，印度尼西亚效仿，时任总统佐科·维多多签署了一项规定，对 18 岁以下儿童实施性暴力的施暴者也将面临长达两年的化学阉割。

在泰国，化学阉割是自愿的，罪犯在接受精神科医生和内科专家的评估后同意接受治疗。这项于2023年生效的法律允许性犯罪者通过注射激素阻断剂来降低性欲，从而获得提前释放。

世界上还有哪些地方允许化学阉割？

在美国，包括加利福尼亚州、德克萨斯州、阿拉巴马州和佛罗里达州在内的几个州对屡犯或情节严重的性犯罪者实施化学阉割。在欧洲，英国、丹麦和德国等国提供自愿化学阉割项目，而波兰和俄罗斯等国则将其作为强制性刑罚。

支持和反对化学阉割的论点和证据是什么？

新加坡社会科学大学法学院高级法律讲师保罗·张在《新加坡法律公报》上撰文指出，化学阉割的有效性尚无法确定。

他指出，对于何时应该启动化学阉割、谁应该承担治疗和监测费用，以及性犯罪者可能滥用其他药物来对抗化学阉割药物，目前还没有达成共识。

他说：“要求进行化学阉割的呼声此起彼伏，但医学和法律文献却对此保持着令人震惊的沉默。”

其他人也指出其中涉及伦理问题，印尼的医生在法律出台后拒绝实施化学阉割，该国的人权研究人员称该程序“不人道”且是一种“有辱人格”的惩罚形式。

支持化学阉割的人指出，化学阉割具有可逆性，而且在自愿项目中，罪犯同意接受药物治疗以及其他程序（如心理治疗），再犯率会显著下降。

例如在英国，激素抑制药物会与其他形式的精神治疗一起服用，以解决性犯罪的其他原因，例如对权力和控制的渴望。

在韩国，韩国犯罪学与司法研究所进行的一项研究显示，接受激素药物治疗的罪犯性犯罪再犯率总体下降了 92%。

但官员们指出，持续治疗费用高昂，据估计，每位罪犯每年需花费500万韩元（约合4720新元）。一项研究强调了持续治疗的必要性，该研究发现，罪犯在停止治疗后的头两个月内，睾酮水平会意外升高，性欲和性幻想也会异常强烈。

新加坡国会