Pre-existing Conditions, Placebo Reactions, and "Side Effects"

Abstract

Studies were made in well subjects and patients to determine the pretreatment incidence of symptoms often included among reported drug side effects, and the subsequent results of placebo administration. A variety of "side effects" symptoms was present prior to treatment. Placebos tended to accentuate the severity of these symptoms in many and to elicit symptoms in others. Adverse placebo effects were more evident in well subjects than in patients. The type and incidence of these symptoms varied with sex, age, the nature of the subject population, and the illness. The data suggest the importance of determining pretreatment incidence of symptoms and of using placebo controls in establishing true drug side effects.