What is the Nocebo Effect?

You may have heard of the placebo effect, which makes people feel better even though they’re taking a pill or getting a treatment that should have no effect at all. But have you heard about the nocebo effect? 

With a placebo, something that is not useful makes you feel better because you believe it will. Nocebo's are different - they’re something that is not harmful, but makes you feel worse because you believe it will. The nocebo effect has been described as a “mind virus,” and the main reason they occur is education.

Wait, you say - isn’t education a good thing? Not when you read the list of potential side effects of a new medication and become convinced that you’re suffering from one or more of them. The nocebo effect can cause real pain and symptoms, as well as measurable changes in your heart rate and blood pressure. 

How common is the nocebo effect? More common than you might think. One study found that 67 percent of people taking placebos - pills with zero active ingredients - experienced side effects. These pills could not cause side effects on their own, yet they did because the study participants were afraid they might. In fact, in most double-blind controlled studies, an average of nearly ten percent of people taking harmless placebos in the so-called "control group" experience such bad side effects that they drop out of the study.

Physicians know about the nocebo effect but often don’t know how best to deal with them. For example, it would be unethical not to tell patients about the potential side effects of a medication, yet the more the patient knows about side effects, the more side effects they are likely to get.  

One of the biggest dangers is when food becomes a nocebo, which is becoming more common with the popularity of gluten-free and Paleo diets. With today’s level of social sharing, one person’s symptoms can quickly become another person’s. When your best friend swears she never knew she had a problem with gluten until she switched to gluten-free, it's easy to ask yourself if you might have a hidden gluten problem too. Soon you've convinced yourself that you have all the symptoms of gluten intolerance and should join your friend on her gluten-free diet.

In fact, this was demonstrated in a study of college students who were given an inactive placebo said to reduce their test anxiety. When some students experienced nocebo side effects, their friends in the study, who knew of the reactions, were even more likely to get side effects from the placebo medication.

I think I’ve had nocebo reactions before, which is why I ask my doctors to tell me only the life-threatening side effects of a new medication (like a heart attack) and not the smaller, more common side effects. You could try this too if you think you may be prone to experiencing a “nocebo” reaction.  

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Used under Creative Commons Licensing courtesy of Roger Newbrook