Abstract
The nocebo effect, the inverse of the placebo effect, is a well-established phenomenon,
yet under-appreciated. It refers to nonpharmacological, harmful, or undesirable effects
occurring after active or inactive therapy. The frequency of adverse events can dramatically
increase by informing patients about the possible side effects of the treatment, and
by negative expectations on the part of the patient. Patients who were told that they
might experience sexual side effects after treatment with β-blocker drugs reported
these symptoms between three and four times more often than patients in a control
group who were not informed about these symptoms. Nocebo effect has been reported
in several neurological diseases such as migraine, epilepsy, multiple sclerosis, Parkinson's
disease and neuropathic pain, and in patients with depression. The investigation of
the biological and theoretical underpinning of the nocebo phenomenon is at an early
stage, and more research is required. Physicians need to be aware of the influence
of nocebo phenomenon and be able to recognize it and minimize its effects.
Keywords
Drugs - medical ethics - nocebo - placebo - treatment
