Nothing to Fear But... Nocebo

As severe as nocebo reactions are, there is a good side. They show how powerful the mind is and what a strong effect it has on our body.
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You may have heard of the placebo effect -- people feeling better from taking pills without any active ingredients -- but do you know about placebo's evil twin, nocebo?

With a placebo, something that is not helpful makes you feel better because you think it will. With a nocebo, something that is not harmful makes you feel worse because you expect it to. Nocebos are mind viruses. They spread through education, and they can cause very real pain and suffering like they did for Peggy.

Peggy came to see me for help with her headaches. She got them several times per week, leaving her unable to function for hours. She explained to me the headaches first came on when she was in college. Initially, they were minor and would go away when she took magnesium, but one day, magnesium seemed to make them worse. The day was memorable because she was preparing to give a presentation for her least favorite class: speech and debate. She found herself worrying she would get a headache and be unable to perform. Since magnesium had helped stop headaches before, she took it as a prevention. This seemed to backfire, leading into her worst headache to date. Over the next several years, she tried more supplements and medications, but none was helpful. Multivitamins, B vitamins, antioxidants, herbal blends, headache medicines -- all the things she thought would help seemed to make her headaches worse. Her hope was that I could provide her with a new supplement she may not know about.

As we started to talk, Peggy showed me a log she had kept of her efforts over the last year. It showed when the headaches came on, how long they lasted, how bad they were and which pills she was taking. From her log, it was evident she never went more than a day without a headache and rarely more than a day without trying a new pill or retrying an old one.

Peggy happened to have a horrible headache after taking a magnesium pill all those years ago. In her mind, she linked the two events and formed the belief that the pill caused the headache. This left her fearful, since something she thought was safe seemed to harm her. The fear raised her risk of headaches, and the fear of reacting to the pill spread to a fear of other pills. It became a vicious cycle. I not only believed her headaches were real and troublesome, but also that a different pill was not the answer for her. I believed she had put a lot of effort into trying to understand her symptoms, and it might be taken as a lack of respect if I suggested her fear was the culprit. I knew that any insight would have to be hers for it to be effective. I suggested we start from scratch and see how many headaches she got over the course of a month in which she did not try anything new. She was worried her headaches would be out of control, but she was desperate enough to try.

Her first week was tough. She had headaches almost every day but did not try to treat them. The next week, she had just a few. The last two weeks, she only had one. It had been years since she had gone that long without a headache. She was ecstatic! She asked me if I thought it were possible that her fear of reactions was causing some of her headaches. I told Peggy that fear was powerful and explained the nocebo response to her.

According to medical research, nocebos can cause symptoms like
: [1]
  • Headaches
  • Depression
  • Fatigue
  • Pain
  • Irritable bowel syndrome
  • Cough
They can also cause measurable changes in things like:
  • Heart rate
  • Blood pressure
  • Athletic performance
  • Coronary artery blood flow
  • Pulmonary function

But this can't be common, can it? You might be surprised. In one analysis of clinical trials, it was found that 67 percent of people taking placebos, pills with no active ingredients, experienced side effects. They were taking a pill that could not cause a side effect, yet two-thirds of people experienced side effects only because they were afraid they might. In fact, nearly 10 percent of people in studies, taking harmless placebos, experienced such bad side effects they dropped out of the studies. [3]

Medical researchers know about nocebos but are often at a loss how to deal with them. For example, it would be wrong not to tell people about possible side effects of a medicine, yet the more they are educated about side effects, the more side effects they will get. [4] This must be limited to certain types of people, right? Not really. Studies trying to identify who is most prone to nocebo reactions showed no one is immune, and the trends are not what one might suspect. For example, driven and confident, type A people are more likely to have a nocebo reaction rather than less likely. [5]

I think the biggest danger is when food becomes a nocebo, and I worry it is getting more common with all the readily-available health information. Imagine a person with a real sensitivity sharing their symptoms in writing when they eat the offending food. Others can read their writing and become concerned they could get the same symptoms. This worry alone can cause very real symptoms.

The more connected we are, the more we are at risk of picking up on nocebo reactions. In one such study, a group of college students was given an inactive medicine said to reduce their test anxiety. When some students experienced nocebo side effects, their friends in the study, aware of the reaction, were even more likely to get similar side effects from the inactive medicine. [6]

Think about what a trap that could become. I have seen it cause devastating effects on people. Hans was a patient of mine whose chief concern was his inability to eat anything without his stomach burning. Although he stood over 6 feet tall and used to be well-muscled and athletic, he now weighed only 140 pounds. Several gastroenterologists could find no cause for his symptoms and no medications that could help him. He tried the most exotic foods imaginable, such as hippopotamus meat and mallow leaves, but everything hurt him. He was wasting away.

As severe as nocebo reactions are, there is a good side. They show how powerful the mind is and what a strong effect it has on our body. This worked to Hans' advantage. Although he was not willing to consider that his beliefs were affecting his digestion, he was willing to try to see if guided imagery could heal his stomach. After several sessions, in which he visualized white light from his mind fixing his stomach, he found his pain decrease. Soon, he was able to eat a wider variety of foods. Within several months, he was feeling great and back to playing rugby.

If you find yourself having more and more reactions to things that should be safe and that you tolerated in the past, consider the chance that the cure may be closer than you thought.


1. Greville-Harris M, Dieppe P. Bad Is More Powerful than Good: The Nocebo Response in Medical Consultations. Am J Med. 2015 Feb;128(2):126-129. doi: 10.1016/j.amjmed.2014.08.031. Epub 2014 Sep 16. Review.

2. Meissner K. Placebo responses on cardiovascular, gastrointestinal, and respiratory organ functions. Handb Exp Pharmacol. 2014;225:183-203. doi: 10.1007/978-3-662-44519-8_11. Review.

3. Mitsikostas DD, Chalarakis NG, Mantonakis LI, Delicha EM, Sfikakis PP. Nocebo in fibromyalgia: meta-analysis of placebo-controlled clinical trials and implications for practice.
Eur J Neurol. 2012 May;19(5):672-80. doi: 10.1111/j.1468-1331.2011.03528.x. Epub 2011 Oct 4. Review.

4. Cohen S. The nocebo effect of informed consent. Bioethics. 2014 Mar;28(3):147-54. doi: 10.1111/j.1467-8519.2012.01983.x. Epub 2012 Jul 5.

5. Drici MD, Raybaud F, De Lunardo C, Iacono P, Gustovic P. Influence of the behaviour pattern on the nocebo response of healthy volunteers. Br J Clin Pharmacol. 1995 Feb;39(2):204-6.

6. Faasse K, Grey A, Jordan R, Garland S, Petrie KJ. Seeing Is Believing: Impact of Social Modeling on Placebo and Nocebo Responding. Health Psychol. 2014 Dec 29.

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