Using drugs to simulate effects of castration is the British government's latest initiative to check paedophilia.
The government has offered what is called chemical castration to convicted paedophiles after research showed that the use of drugs can reduce further risk of offending.
Britain becomes only the fifth country in the world to take the medical route to check paedophiles after Sweden, Denmark, Canada and eight states in the USA.
The programme has been considered successful in these countries. Australia is an exception with its government saying existing scientific proof is not enough to implement it.
Two types of medication are available to treat sex offenders. The first are known as SSRIs (selective serotonin re-uptake inhibitor), commonly prescribed for depression, anxiety, and obsessive compulsive disorder. They help govern activities such as eating and sleeping, and sexual activity.
The second are classed as anti-libidinal medication, which reduce testosterone levels to those found in pre-pubescent boys and decreases sexual interest and arousal. Offenders become less interested in sex and there is a great reduction in spontaneous sexual behaviour.
Professor Don Grubin, a criminal psychiatrist, from Newcastle University's Institute of Neuroscience, has been appointed by the Department of Health to coordinate the treatment nationally.
He is running an advisory to identify those who would benefit from anti-libidinal medication, which includes Prozac and cancer drugs.
Prof Grubin said the treatment would only be available at the end of an offender's jail sentence and not as an alternative to prison.
He said: "This isn't part of the punishment, but aims to reduce the likelihood that they will need to be punished again. The question is, do you want them out there with treatment, or without it?"
Prof Grubin has set up the National Psychiatric Offender Advisory Service, to which medical staff from across the country can refer offenders for psychiatric assessment and medication.
A Ministry of Justice spokesman told The Telegraph: "Evidence suggests that certain types of medication can be useful in reducing the risk from certain sex offenders.
The only treatment previously available to sexual offenders through the National Offender Management Service (Noms) was of a psychological nature.