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How to Define, Find and Classify Side Effects in Psychotherapy: From Unwanted Events to Adverse Treatment Reactions


  • Michael Linden

    Corresponding author
    1. Department of Behavioural and Psychosomatic Medicine, Rehabilitation Centre Seehof, Teltow/Berlin, Germany
    • Research Group Psychosomatic Rehabilitation, Charité University Medicine Berlin, Berlin, Germany
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Correspondence to: Prof. Dr Michael Linden, Research Group Psychosomatic Rehabilitation, Charité University Medicine Berlin, Lichterfelder Allee 55, 14513 Teltow, Germany.




Empirical research on the negative effects of psychotherapy is insufficient, partly because there is a lack of theoretical concept on how to define, classify and assess psychotherapy side effects. This paper proposes a model for the definition, classification and assessment of psychotherapy side effects.


Definitions are provided for ‘unwanted events’, ‘treatment-emergent reactions’, ‘adverse treatment reactions’, ‘malpractice reactions’, ‘treatment non-response’, ‘deterioration of illness’, ‘therapeutic risks’ and ‘contraindications’. We describe processes analysing the causality of negative events and the correctness of treatment.


A procedural model on how to find, classify and evaluate negative events is described, the unwanted event to adverse treatment reaction (UE–ATR) checklist.


Recognition of adverse treatment effects is a characteristic of good therapists and treatments. Psychotherapists should be sensitive for negative effects. This can help improve the quality of treatment. The UE–ATR checklist can be used in psychotherapy trials, quality assurance, clinical practice and training of psychotherapists.Copyright © 2012 John Wiley & Sons, Ltd.

Key Practitioner Message

  • If you do not find adverse treatment effects, then ask yourself why and do not assume that there are no side effects.
  • The detection and management of adverse treatment effects is not a sign of bad but of good clinical practice.
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