The Nocebo Effect: When Negative Expectations About a Treatment Result in Real Negative Outcomes
The Nocebo Effect: When Negative Expectations About a Treatment Result in Real Negative Outcomes

The Nocebo Effect: When Negative Expectations About a Treatment Result in Real Negative Outcomes

This article is about studies on the nocebo effect – the opposite of the placebo effect (which I have also written about – read more here).

The nocebo effect is an expectation about negative treatment outcomes which in itself causes worse treatment outcomes.

The nocebo effect seems to have similar or even larger effects on clinical outcomes than the placebo effect as negative perceptions are formed much faster than positive ones (Greville-Harris & Dieppe, 2014).

Some authors state that:

Physical complaints, such as pain, can be effectively altered by placebo and nocebo effects due to induction of positive or negative expectations … Results on contagious itch suggest that itch sensations might be even more susceptible for placebo and nocebo effects than pain … Expectation mechanisms, such as preservative worrying about negative consequences, are relatively consistent predictors of future disease outcomes (Evers & Colleagues, 2014).


The nocebo effect is prevalent in interactions between patients and healthcare workers. Research has demonstrated that if a patient deems a healthcare professional not to understand or believe them, this can cause distress, and the physiological effect can reduce the prognosis of treatment. It has also been demonstrated that patients who are anxious or expect pain during a procedure, feel more pain because of this negative expectation (Horsfall, 2019)

So, how is it even possible to minimize the nocebo effect? Glick (2016) suggests the following:

… Negative information about what a patient will feel—expectations—should be minimized. Rather than pointing out how painful an injection will be, the patient should be told that they may feel only some discomfort. As conditioning plays a big role, it would be beneficial, if possible, to start treatment with less pain-inducing procedures rather than have a patient associate a visit to the dentist with a painful experience. Invalidating patients’ preferences and values may also induce a nocebo response, and this effect should be recognized when communicating with patients.

Aas you can see by now, the psychological mechanisms behind any treatment cannot be neglected. As the mind is always with us, psychological factors cannot be separated from any physical treatment outcomes and it should therefore be handled in clinical practice as well.

To finish this article, let’s look at a recent study on back pain patients and the nocebo effect (2021):

44 low back pain patients were randomized to Group A who had a factual explanation of their MRI report or Group B, who were reassured that the MRI findings showed normal changes. The outcome was compared at 6 weeks … Both groups were comparable initial by demographics and pain. After 6 weeks of treatment, Group A had a more negative perception of their spinal condition, increased catastrophization, decreased pain improvement, and poorer functional status. Conclusion: Routine MRI reports produce a negative perception and poor functional outcomes in low back pain patients. Focussed clinical reporting had significant benefits, which calls for the need for ‘clinical reporting’ rather than ‘Image reporting’.