Nocebo vs Placebo Effects: Their Clinical Relevance.

The placebo effect can be defined as any improvement of illnesses or reduction of subjective symptoms that result from interventions possessing no known physical effects. By contrast, the nocebo effect refers to undesirable symptoms or illnesses that follow interventions also lacking known physical effects. It may also play a role in chronic illnesses that lack objective confirmation.

Somatic symptom disorders without known physical causes: one disease with many names?

Patients complaining of pain or fatigue in the absence of known physical diseases constitute a high percentage of those seeking general medical care. Depending upon the type of physician/specialist consulted, those individuals may receive disease labels that range from an implied psychological origin such as somatoform or psychosomatic disease, or to a presumed physical disease such as fibromyalgia. Although all these conditions are regularly associated with fatigue, we have provided a new label suggesting another disease category, "systemic exertion intolerance disease," which replaces the previous "chronic fatigue syndrome.