Whether treatment consists of an active drug or a placebo, the clinical setting that surrounds treatment includes multiple types of context information that are perceived and interpreted by the patient’s brain. The external context includes treatment, place and social cues, along with verbal suggestions. The internal context consists of memories, emotions, expectancies and appraisals of the meaning of the context for future survival and well-being. These features combine to make up the treatment context and are the ‘active ingredients’ of placebo effects.