In respect of the Stages of Change, this describes the falling back into prior (harmful) patterns of substance using behaviour.

In respect of a major mental illness such as Psychosis, it describes the recurrence of more florid patterns of illness.

It is important that in either sense of the word, Relapse is not to be seen as failure, as it is common - and many successful treatments occur after one or more relapses.

Relapse prevention work and plans drawn up as part of Crisis Contingency Planning are an important part of sessions once the possibility of stable change is made real.