Drug abuse is able to modify the state of consciousness and, as a consequence, the sense of reality. The author describes two fundamental modifications of the sense of reality under drug effect: “floating” and “frozen”. The first, “floating” is induced by acute intoxication; the second, “frozen”, is produced by chronic drug dependence. These two reality modifications are described from a phenomenological and a psychopathological perspective. Intentionality, space, time, otherness are described in their different “floating” and frozenstructure. “Floating” patients need of adaequate medical treatment. In conclusion, the author introduces the dasein-group treatment, based upon shared emotions, as a concrete possibility to cure frozen patient.