When Pessimism Can Make You Sick: The Nocebo Effect

written by Cody MacInnis - Mar 26, 2018

Photo Credit: by Kristina Campbell
Photo Credit: by Kristina Campbell

Let’s play a word game. What comes to mind when you hear the word “gazebo”?… a covered structure? Yep, point for you. Ok, what about “placebo”? …the sort of miraculous healing thing? Another point for you. One more: “nocebo” …hmm, complete silence.

With the relative lack of information relating to the nocebo response in the scientific community, one would be hard pressed to encounter an individual on the street who could provide an accurate definition for this serious neuro-biological phenomenon. So what exactly is this thing? Well, the nocebo response is the pessimistic cousin of the charming and more commonly known “placebo.”

In a clinical context, the placebo effect is defined as the positive physiological results an individual receives from a therapy that lacks any inherent pharmacological treatment. Scientists have been aware of the placebo effect for decades and have tried to minimize the effects of this phenomenon in experimental studies through the implementation of double blind procedures. The purpose of these procedures has been to remove any bias, preventing the development of any expectations in the researcher or the experimental participants. Through neurobiological processes, bias can influence expectations that create undesired physiological responses in test subjects, and confound the results of experimental studies. Over the last several decades, the medical research field has increasingly discovered the power of this expectancy effect giving sugar pills to patients with very real symptoms, and watching as balding patients have regrown hair, blood pressure has been lowered, and equal improvements have been observed in knee pain of patients who underwent fake surgical procedures that were meant to mimic actual arthroscopic procedure. The nocebo effect works in much the same way, but with a significant difference. While the placebo effect uses neurobiological pathways that work with positive expectations, the nocebo effect relies upon different pathways that respond to negative expectations. The etymology of these words does well to explain the difference: in Latin the word placebo means “I will please” while nocebo means “I will harm.”

The nocebo effect phenomenon is a vivid example of the neurobiological (mind-body) processes that shape one’s health. Although there is some debate as to what in fact defines the nocebo effect, recent empirical evidence from experimental and observational research concludes that the nocebo effect is real and can be described as the occurrence of negative health symptoms resulting from an individual’s pessimistic expectations. An American study done in 2008 found that nocebo induced hyperalgesia (a state of heightened pain) which occurs through the medial pain system with the hippocampus area of the brain playing a major role. Expressions of this phenomena arise from a combination of psychological and social factors, including gender, prior experience of negative potential in therapies, personality types, as well as increased stress from morbidities and age. Studies showed that individuals with type A personality were 3 times more likely than those with type B personality to develop nocebo responses. As well, a study of the Italian population showed that women when compared to men had a 10% increase in nocebo responses when exposed to drugs with adverse side effects.

Within the medical healthcare system, physicians hold an incredible amount of social and cultural authority over those who seek their assistance. A doctor’s authority stems from their broad knowledge regarding the biological processes of the body, from the professionalism they exemplify in clinical settings, and also from a cultural belief system that highly values biomedical healing. Due to this position in society, communication from physicians regarding the health status of their patients, is commonly accepted by the patient as factual, and depending upon the communication verbalized by the physician, can create either a positive or negative expectation in the mind of the patient. Within the medical profession certain policies have been implemented with the patient’s best interests in mind. One of these policies is “informed consent.” This process legally binds physicians to revealing all important relevant information regarding an individual’s health status--regardless if the information is positive, negative, or whether it is highly likely or only slightly likely to happen. Although this binding agreement is in the best interests of patients, through the complex workings of the nocebo effect this communicated information can create negative expectations in the minds of patients that sometimes lead to serious harm and even death. As renowned physician and original developer of the DC defibrillator Bernard Lown once said: “Words are the most powerful tool a doctor possesses, but words, like a two-edged sword, can maim as well as heal.”

Within a clinical context the nocebo effect has a considerable impact. One of the main issues that arises when patients that are susceptible to adverse reactions from what is voiced by physicians, or written on pill bottles, is that increased suffering from hyperalgesia, nausea, IBS, etc. forces many patients to withdraw from therapeutic measures. These patients receive no cure, they lose hope in the medical system and if prescribed antibiotics their actions might compound the already dire situation surrounding antibiotic resistant pathogens stemming from poor adherence to drug regimens. Analgesic pain killing drugs are particularly susceptible to the nocebo effect. A recent study showed that if patients received information about the occurrence of pain on only one occasion it would induce hyperactivity of the insular cortex for a period of 8 to 90 days. This leaves many patients enduring increased stays in hospital beds suffering from pain that only exists as a result of an expectation. These extended stays are a cause of efficiency in public healthcare systems. Nocebo effects have also been shown to have a significant impact on the quality of life (QOL) of patients after chemotherapy treatments. A recent study classified cancer patients into three categories based upon expectancy levels. Levels were associated with the occurrence and severity of post chemotherapy nausea. Results showed that those in the higher expectancy category endured significantly higher levels of both average and peak nausea. On average this resulted in this group of patients experiencing a QOL that was 20% worse than other patients. Nocebo effects create an increased amount of suffering in the lives of individuals simply seeking cures for their ailments.

This phenomenon has serious implications not only in clinical settings but also on a societal level. In the modern digital age the development of new media such as the internet and smartphones have significantly increased an individual’s access to health information. The issue that arises from this is that often trending popular health information is inaccurate, arising from flawed interpretations of scientific findings. If false trending health information reaches a broad audience, it can influence the beliefs of this large group and thereby initiate the nocebo effect on a grand scale. This has been defined as sociogenic illness: the spread of an illness or negative physiological symptoms throughout a population, without any pathogenic basis, resulting from an accepted belief within the group. The recent trend within natural health circles to consider gluten highly problematic for individuals has led to mass anxiety regarding the consumption of wheat. According to this trend, wheat, a food that has nourished humanity for thousands of years, has suddenly become a health threat to anyone who chooses to eat it. Based on this assumption, at the height of the gluten trend, between 2009 and 2014, reported gluten sensitivities tripled while the number of medically diagnosed cases of gluten autoimmune disorder, known as celiac disease, remained consistent--affecting roughly 1% of the population. Celiac disease has a genetic basis and the sufferers experience an array of undesirable symptoms including; nausea, bloating, stomach aches, chronic diarrhea, chronic fatigue, and even anemia in severe situations. Although the large number of individuals self diagnosed gluten sensitivities have no genetic basis for the symptoms they experience, their symptoms are very real and affect them in much of the same way as those who in fact have celiac disease. What or whom is to blame for this suffering, one might ask? The nocebo effect strikes again, this time using media sources and false health information to negatively influence the health of modern humans.

Some hope may exist however, in the case of the nocebo effect a ground breaking study done by a group of Dutch medical researchers has shown that this can in fact be reversed. Through first using a conditioned stimulus the team induced strong itching sensations within study participants. Following this they sat down with each participant in a one on one setting and used a combination of positive verbal suggestioning and counterconditioning. The results showed that one session was sufficient to either minimize or completely reverse the prior induced nocebo effects. Being the first study of its kind, it was noted that further examination would be needed to analyze the long term effectiveness of this procedure.

As the clock ticks, patients are left in agony to endure the full severity of their conditions, analgesic drugs are rendered useless (callously defeated by negative expectations), and the masses are deceived by fraudulent health information. Although there are glimmers of hope, more studies are urgently needed to develop a deeper understanding of this phenomenon and to develop treatment models to eliminate the unnecessary suffering of hospital patients worldwide. The nocebo effect reminds us of the immense power of the mind and of the influence of authoritative sources. In light of the nocebo effect, being told to “look on the bright side” might be some of the best advice one could hope to receive.


Cody MacInnis is a writer currently studying the connections between biological and mental processes in Victoria B.C. His free time is spent outside enjoying the fresh Vancouver Island air.

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