Social nocebo1 is a contagious illness that impacts upwards of one-quarter of people who encounter it. Conditions are ripe for a rise of social nocebo in the workplace. The following are key actions that occupational safety and health pros must take to anticipate, recognize, evaluate and control social nocebo.

What’s social nocebo?

Dr. Fabrizio Benedetti, a professor of physiology and neuroscience at the University of Turin Medical School in Turin, Italy, is a leading researcher on social nocebo. Dr. Benedetti’s 2014 research involved a group of test subjects taken up into the Alps for a hike. Benedetti planted a thought among some hikers about headaches at high altitudes and 86 percent of subjects who thought they’d get a headache in fact got a one, compared with 52 percent in a control group.

People believing that they are sick can be contagious. That’s social nocebo. Sick building syndrome, psychosomatic disorder, even voodoo hex, are examples of other names for social nocebo. The opposite of nocebo is placebo – where positive thinking has beneficial health effects.

Rise of social nocebo

The rise of social nocebo corresponds to the growth of “Dr. Google.” Pew Research “Health Online 2013” found that more than 35 percent of U.S. adults have gone online to figure out some medical condition. People read to their level of understanding.  What they don’t understand; they fill in with alternate facts.

Misery may like company – which is another reason for rise of social nocebo. A 2015 research study published in The Lancet found that 95 percent of people in the world have health problems, with more than a third having more than five ailments2. A 2013 study by Gallup-Healthways ranks the major occupations in the U.S. that take the most sick days3. For example, 82 percent of manufacturing/production employees have a chronic health condition that equates to cost of lost productivity at $2.8 billion.


Social nocebo begins with planted thoughts, such as Benedetti’s mentioning probability of headaches to test subjects. There are two main components: One, two or more people in near proximity to each other have similar symptoms of poor health; and, two, “something” within the proximity is thought among the group to be the source of the poor health. OSH pros may consider the possibility of social nocebo if “nothing” within the work proximity could be a source of poor health.


Everything that may cause ill health must be considered. Where practical, and necessary, samples are collected, analyzed and compared with recognized safe levels. Not all samples should be taken and measured, however. For example, you may sample for airborne mold and get numbers, but if there are no recognized safe levels for the mold species found, then what? There’s nothing wrong about using professional judgment, without numbers, to conclude the environment is safe.

Evaluating doesn’t stop at normal chemical, physical, radiological, or biological hazards. What’s the collective mental state of the workgroup? Are they stressed? Angry? Who’s the “leader of the pack?” 

Evaluate by being engaged, listening, and talking. Remember, social nocebo begins with a planted seed. Are there direct, or more often, indirect planting of seeds of ill health? The source may even be poorly presented HazCom training.

Sending employees out for medical evaluation actually may further the nocebo effect. Headache, nausea, malaise, and weakness may be associated with many workplace exposures. Medical providers are often very cautious, and lacking evidence, may suggest to the employee that something at work may be causing ill-effects.


Nocebo is controlled by placebo. In Latin, placebo means “I shall please.” The OSH pro must be the placebo. To serve as a placebo the OSH pro must be perceived by employees as honest, trustworthy, empathetic, educated, qualified (credentials help) and concerned.

If the pro says, “I’ve looked and looked, I can’t find anything that would cause someone to get sick in this environment” and people firmly believe the statement, then the positive seeds of the placebo are planted to counteract nocebo effects.

Nocebo is fueled by rumors. If nocebo is suspected, the best way to control rumors is to openly discuss nocebo concerns. During employee meetings, if held, discuss nocebo including providing a copy of the Wikipedia definition1. The point of the Wikipedia example is to engage discussion of what employees have found online. This opens up discussion of actual workplace risk as opposed to theoretical risks found online.

Fake news is the rage today. But fake is in the eye of the beholder. And this is another nocebo concern. Workplace health risks require that the OSH pro to wade through many online information sites to determine what news is real and credible. Re-explaining the information in a manner that employees understand furthers the challenge.

For OSH pros that have not experienced the gray areas of online health information, pick a topic such as “health effects of EMF exposure” or “health effects of mold exposure” and read through the first dozen or so entries. You might be surprised at the wide range of risk information. Simply telling employees the workplace is in OSHA compliance exposures often is not enough to stop nocebo concerns.


As an IH consultant I’ve encountered the nocebo effect many times, perhaps as much as one-third of my health investigations in recent years. The nocebo effect is real and left uncontrolled may disrupt the workplace, causing lost production and unnecessary concerns. Although most suited for industrial hygiene practice, every OSH pro and allied professions such as HR should learn more about nocebo effects and control.


1. Nocebo definition

2.  Lancet 2015 research

3. US Workers taking most sick days 2013 study