Why is it a sin to use drugs?

Every form of a person’s dependence on legal substances (alcohol, medications or tobacco) and even more so on illegal drugs is an exchange of freedom for slavery: it damages the health and life of the person concerned and also does great harm to the people around them. Every time a person loses himself or forgets himself by becoming intoxicated, which can also include excessive eating and drinking, indulgence in sexual activity, or speeding with an automobile, he loses some of his human dignity and freedom and therefore sins against God. This should be distinguished from the reasonable conscious and moderate use of enjoyable things.