The placebo effect is now well known – the nocebo effect, on the other hand, is probably not as familiar to many – but it represents a significant influence in medicine.
The nocebo effect (from lat. nocere = to harm) can be described as a negative placebo effect – so an influence that has no specific effect, but still triggers a negative reaction. Like the placebo effect, the nocebo effect is based on a certain expectation, which can be either unconscious or “learned”. Patients may fear that certain external influences, usually medications, but also certain interventions and procedures, will make them sick. These people then actually get sick or observe certain symptoms in themselves. The effect is usually amplified by detailed explanations of the risks and side effects of medications – and this brings us back to the package insert, about whose abundance of information I already wrote in my last blog.
The nocebo effect can be observed in drug studies that are conducted in a double-blind design, i.e. neither doctor nor patient know whether a patient is receiving the test substance or a placebo. In drug studies, all patients must be informed in detail about the risks and side effects of the test substance for ethical reasons, regardless of whether they receive the test substance or placebo. About a quarter of the placebo recipients then complain about the corresponding side effects previously explained to them.
An example published in 2007 of a young student who took a complete month’s supply of a medication he had received as part of a drug study during a suicide attempt shows how pronounced the nocebo effect can be. Although the tablets he took were only placebo, he developed a medically critical condition. His condition normalized only after he was informed that he had not taken any active ingredient.
Therefore, to assess the actual side effects of a drug, the nocebo effect of the control group should be subtracted (just as the placebo effect is subtracted when assessing the effect of a drug).
It also becomes clear that it is ultimately not a sensible strategy to simply list side effects in the package insert that have been observed in clinical studies. An explanatory weighting would ultimately be much more useful. Furthermore, there is the problem that the abundance of information about risks and side effects in a package insert leads to a self-fulfilling prophecy for a large proportion of those affected due to the nocebo effect – they actually suffer from the expected side effects.
This not only incurs large costs for the healthcare system, but also means that potentially effective and useful medications are not taken at all. This is a big problem especially with diseases like MS.
A solution lies in a stable doctor-patient relationship in which the benefits and risks of drugs are realistically discussed and which is able to address patients’ worries and concerns. This requires a high degree of trust in the doctor’s assessments and recommendations. Unfortunately, this important prerequisite is often questioned by the abundance of information from the Internet, self-diagnosis (Dr. Google) or an overloaded package insert.
