It depends what type of CBT. The Chalder protocol is potentially harmful in that it aims to increase activity. For most other disorders, CBT is focused on resolving specific issues that en has e.g. depression. It is therapeutic. It can help or it has no effect.
Sorry, but this is a view, I (and other therapists) cannot share. Psychotherapy is never completely harmless. Like every medical intervention it can have serious adverse effects. CBT is not excluded. Especially because the therapist has a greater knowledge base, the patient is often in a vulnerable and desperate state, the therapists has to identify cognitive distortions and maladaptive behaviour correctly, and the goal of CBT is to retrain and recondition certain thought processes and behaviours, it can have negative consequences due to mistakes by the therapist, misunderstandings by the patient, changes of social behaviour, provocative qestions, excessive demands, outright manipulation or (sometimes yet unkown) other factors. This is an issue with has been overlooked for a long time, but research is getting there. Don't get me wrong, CBT can be a great and very successful form of treatment and def has great value for a lot of patients, but it's is not entirely harmless.
Some quotes from a review, called: "The elephant on the coach: side effects of psychotherapy."
"[...] 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."
"If psychotherapy is provided as the only or principal therapy for a condition for which it is either inappropriate or ineffective, the patient may be exposed to a lengthy period of ongoing symptoms and disability – an adverse outcome."
"Psychiatric patients are commonly highly troubled and vulnerable, whether personality based, and/or a consequence of their illness. An insensitive, critical or sexually exploitative therapist may increase a poor outcome risk."
"It has been suggested that therapists who induce high emotional arousal may inadvertently cause an increase in alcohol consumption, especially in those with comorbid mood disorders [
14]. Interventions that risk increasing a person's feeling of being stigmatized or in which they are blamed for not meeting intervention targets, have been held to increase helplessness and self-blame, and so undermine self-efficacy [
15]."
"Szapocznik and Prado detailed how interventions may have adverse effects on families and friends [
16], particularly if the individual undergoing therapy becomes more self-absorbed or self-centred [
17–
19]."
"The longer any patient attends a psychotherapist – irrespective of how therapeutic the therapy – the patient risks contracting their independent capacity to make decisions (self-mastery), whether by deferring in sessions to their therapist or by filtering decisions outside therapy through the therapist's decision-making model."
"Some patients confronted with such expectations [of critical reasoning]– and unable to meet them (particularly as a consequence of severe depression) – may have their sense of self-worth further undermined. Further, CBT shifts responsibility onto the individual for active engagement and conduct of the techniques. A recipient may feel guilty if treatment does not result in the expected improvements, without realizing that there are many other factors that may affect response."
"Some experienced cognitive therapists suggest that CBT can be toxic to some individuals, particularly those with obsessive personalities, by increasing worry and introspection, fuelling rather than relieving anxiety and depression. Vulnerability to such adverse events may be a consequence of stage of illness [
41,
42]. In bipolar disorder, CBT benefited those individuals in the early stages of illness, while those people who had more than 12 prior episodes of illness actually deteriorated with CBT [
43]."
http://anp.sagepub.com/content/43/9/787.full
