clinical pharmacology
Placebos
Placebo effects
Placebos, although physiologically inactive, may have substantial effects—good and bad. These effects seem to be related to anticipation that the product will work; anticipation ofadverseeffects is sometimes called the nocebo effect. The placebo effect typically occurs more with subjective responses (eg, pain, nausea) rather than objective ones (eg, rate of healing of leg ulcers, infection rate of burn wounds). The magnitude of the response varies with many factors, including the Expressed confidence of the clinician ("this is going to make you feel a lot better" vs "there is a chance this might help") Certainty of the patient's beliefs (effect is larger when patients are sure they are receiving an active drug than when they know there is a chance they are getting a placebo) Type of placebo (eg, injectable drugs have a larger placebo effect than oral ones) Not everyone responds to placebos, and it is not possible to predict who will respond; correlations between personality characteristics and response to placebos have been theorized but not well established. However, people who have a dependent personality and who want to please their clinicians may be more likely to report beneficial effects; those with a histrionic personality may be more likely to report any effect, good or bad. 