EXPLAINER: What you need to know about chemical castration

A proposal to subject sexual offenders to chemical castration has sparked a nationwide debate on whether such a measure would effectively curb gender-based violence.

The recommendation comes from a task force appointed by President William Ruto to investigate the rising cases of sexual violence and femicide in the country.

In a report submitted to the President, the team proposed amending the Sexual Offences Act of 2006 to introduce chemical castration as a measure to restrain and curtail convicted repeat rapists.

“Amend the Sexual Offences Act 2006 to include chemical castration for both male and female child defilers and defilers of PWDs (people with disabilities),” the report recommended.

However, experts are divided on the effectiveness of such a drastic intervention.

Some argue that chemical castration does not change a person’s personality, psychological disorder, or completely eliminate violent behaviour unless used alongside psychotherapy.

Others point out that its efficacy is difficult to measure. “Its effectiveness is hard to demonstrate in reoffending studies because it takes years to see if it is having a long-term effect,” said one expert familiar with global practices.

The treatment also poses financial challenges, as it requires repeated administration over time. This recurring cost is seen as a significant drawback, particularly in resource-constrained settings.

Former Deputy Chief Justice Nancy Baraza chaired Ruto’s task force, formally known as the Technical Working Group on Gender-Based Violence (GBV), Including Femicide.

The 42-member team was mandated to assess the scale, trends, legal, and institutional gaps in Kenya’s response to gender-based violence and femicide, and recommend reforms.

The group conducted nationwide consultations across all 47 counties, engaging survivors, civil society, government agencies, and community leaders.

Violence against women, they found, ranges from verbal harassment and emotional abuse to cyber-attacks and daily physical or sexual abuse.

At the extreme end of the spectrum is femicide, defined as the intentional murder of a woman because she is a woman. The report described femicide as “sad, unfortunate and an outright evil act.”

Chemical castration involves the use of drugs to lower the production of hormones in the testicles.

Other names for the process include hormone therapy, androgen suppression therapy, and androgen depressive therapy.

Its primary aim is to reduce the levels of male hormones, or androgens, such as testosterone and dihydrotestosterone (DHT), which are largely produced in the testicles.

Doctors typically use this treatment to manage hormone-related cancers, including prostate cancer, and in some countries, it has been applied to sexual offenders as a method of reducing libido. 

However, chemical castration is not a one-time treatment. Depending on the drug and dose, it must be repeated as frequently as once a month or as infrequently as once a year.

Side effects can include reduced or absent sexual desire, erectile dysfunction, shrinkage of testicles and penis, fatigue, hot flashes, breast tenderness, and growth of breast tissue.

Medical experts warn that not every person will completely lose sexual function, and that the method relies heavily on long-term compliance.

Ethical concerns have also been raised regarding coercion and potential lack of informed consent, particularly in prison settings.

Internationally, the measure has been implemented in various ways. In the United States, chemical castration was approved in 1966 as a treatment for patients with pedophilic impulses, with California becoming the first state to mandate it for certain repeat sex offenders.

To date, 11 US states have approved its use, though courts rarely adopt it. Russia’s parliament passed a similar law in 2011, while Moldavia introduced mandatory chemical castration for juvenile rapists in 2012.

In Europe, the approach is often voluntary. In Germany and Denmark, chemical suppression is only administered on a voluntary basis. Meanwhile, Poland introduced mandatory chemical suppression for some sex offenders.

In England, the pilot program for voluntary chemical castration is being expanded to 20 prisons. Justice Secretary Shabana Mahmood told the BBC in May 2025 that the pilot would be extended to build evidence and “make sure that we are using every tool at our disposal that can cut reoffending.”

Mahmood is also exploring whether the intervention could be made mandatory, though no timeline has been set.

Despite the debates, proponents of the measure argue that it could be an important tool in the fight against repeat sexual offences, particularly when combined with psychotherapy and rehabilitation.

Critics, however, caution that chemical castration alone cannot prevent violence, may have significant medical and ethical consequences, and could place a long-term financial burden on the state.

As Kenya grapples with rising cases of femicide and sexual violence, the proposal has ignited discussions among lawmakers, civil society groups, and medical professionals about balancing punishment, rehabilitation, ethics, and public safety.

The outcome of the task force’s recommendations could see Kenya join a handful of countries experimenting with chemical castration as a legal intervention for sexual offenders.

Gender Cabinet Secretary Hannah Cheptumo welcomed the recommendations, calling the report “a collective hope and expectation of millions of Kenyans,” and promised her ministry would coordinate its implementation.