Abstinence is the appropriate term that is used when a person abstains from harmful substances while attending an addiction treatment center. It basically means the person should be keeping away from, or not engaging in addictive substances or even behaviors. If a person either permanently or only for a short period of time does not become involved in the addictive behavior at all, that person is known to be abstaining or abstinent, for instance, "She has been abstinent from heroin for 1 year."