I once heard from the Lubavitcher Rebbe, Rabbi Menachem Mendel Schneerson, of righteous memory, in a private audience, an observation about drugs.
He was speaking about the effect on a person taking drugs. He was, incidentally, very careful about not saying anything negative about anybody. He said that the opinion of the Torah in general is that the person should be the master over his or her self, and enslavement of any sort is wrong.
Can a person still be the master over himself when involved with drugs and other addictive substances?
The problem with using any kinds of drugs or almost anything that has a little bit of psychoactive material is the same. Indeed, almost everything is psychoactive, including bread. If one fasts and then takes a piece of bread, it is possible to see how many changes are made in one's psyche.
The specific problem, however, with drugs is that people come relatively fast to a point of no return. In truth there is never a point of no return; but one quickly reaches a point from where it is very hard, almost impossible, to return...