Expectations of medicine adverse effects: Perceptual characteristics of tablets and personality background

Abstract

The possible roles of perceptual characteristics (colour, shape, size) of tablets and personality characteristics in generating expectations of drug side effects were investigated. Two hundred and thirteen hospitalized patients (mean age 48.9 ± 18.84 years) completed questionnaires (trait anxiety — STAI-T, dispositional optimism — LOT-R, subjective somatic symptoms — PHQ-15, somatosensory amplification — SSAS, previous personal and family-level experiences) and the expected probabilities of nine side effects for six differently looking tablets were estimated. PHQ-15, SSAS and family-level experience scores were significant predictors of the expectations of side effects. Red tablets evoked significantly more stimulating type expectations than did white pills. Expected gastrointestinal side effects were associated with oblong-shaped tablets. Regarding headache, medium-sized round tablet was expected to evoke fewer side effects than the small round and the oblong tablets. Although expectations do not always manifest themselves as actual symptoms, they can reduce the overall effectiveness of a therapy by influencing patient's adherence.