Although we take it as a given that many psychotherapies are efficacious, form a cornerstone of much current practice, and are valued by many patients, there is a dissonance in the way in which physical therapies and psychotherapies are considered in terms of their cost–benefit ratio. Any potent intervention has both the capacity to cure and to harm. For drug-based therapeutic trials, adverse event monitoring is mandatory. By contrast, evaluation of psychotherapy has historically weighted the ‘benefit’ side of the equation. For example, is a particular type of psychotherapy effective, is one psychotherapy superior to another, or does psychotherapy benefit a particular condition?
At first pass it might appear bizarre to question whether psychotherapy could be harmful or have substantive side-effects, with Nutt and Sharpe recently observing that there is an ‘assumption … that as psychotherapy is only talking … no possible harm could ensue’ [1]. Certainly, patients rarely raise such concerns. By contrast, when a psychotropic drug is prescribed, most patients inquire about likely drug side-effects, while medico-legal injunctions oblige the practitioner to detail and document substantive side-effects.
Why the dissonance across those treatment modalities if we accept the principle that all effective treatments risk adverse events? In arguing against the common assumption that adverse events of psychotherapy are slight, we offer several examples to argue that substantive costs can emerge from both acts of omission and commission.