I'm against the idea in the first place. Just give them Life w/o parole (for rapists and serious child molesters, I'm not talking about public nudity or 18 year olds caught with 16 year olds).
But if we do this then at least chemical castration is potentially reversible in case it is later proven the person didn't do it.
FALSE CONVICTIONS HAPPEN. Advocates of surgical castration and advocates of the death penalty seem to forget that.
I think sex offenders such as rapists and especially child molesters should be castrated. They will no longer have the ability to assault someone and they will also never again feel pleasure from sex. Just doing it chemically would leave them some sort of manhood and they do not deserve any.
When dealing with castration of sex offenders, I believe that surgical castration would be better than chemical castration. When dealing with chemical castration, it is unknown what adverse side affects may occur over a long period of time. Plus, surgical castration would have far fewer complications as chemical castration may not succeed.