Abstract: Medical research uses placebo controlled clinical trials, yet has neglected the potentially deleterious effects of the nocebo response. It is beyond doubt that placebo response recorded in modern clinical research constitutes an important methodological tool to ascertain the effectiveness of the drug in a particular indication. Before a drug is registered, the legal requirement is to prove the efficacy and safety in adequately well controlled clinical trial.
While the placebo effect refers to the health benefits obtained from a treatment that should not have any effect, patients experiencing nocebo effect experience the opposite. They presume the worst, health wise, and they get adverse effects of a treatment that should not have any effect. In a trial, about 20% patients taking sugar pill (dummy medicine) in controlled clinical trial of a drug spontaneously reported uncomfortable adverse effects. These adverse effects are one kind of nocebo a Latin word which means “I will harm” just opposite to placebo effect which means in Latin “I will please”.
Nocebo can be defined as “harmful, unpleasant, or undesirable reactions or responses that a subject experiences (thus called nocebo reactions or nocebo responses) as a result of administering an inert dummy drug, where these responses had not been chemically generated, and were entirely due to the subject's pessimistic belief and expectation that the inert drug would produce harmful injurious, unpleasant, or undesirable effect.”
In these cases, there is no “real drug” given to patients, but the actual harmful, unpleasant, or undesirable biochemical, physiological, psychological, emotional, and/or cognitive consequences of the administration of this inert drug are very real.
A placebo response makes patients feel better for reasons unrelated to the specific treatment properties. On the other hand, a nocebo response makes patients worse (or does other harm) in the same way. Common symptoms reported with nocebo response are drowsiness, headache, mild dizziness, difficulty in concentrating, and gastrointestinal problems. Many clinicians are often not aware of nocebos, yet these adverse reactions can cause patient dropouts in a clinical trial, stop taking drugs they need, or end up taking other drugs which complicate their treatment.