The Psychology of Multiple Chemical Sensitivity

A Common Comorbidity in Fibromyalgia & Chronic Fatigue Syndrome

Multiple chemical sensitivity (MCS) is a common comorbidity in people with fibromyalgia (FMS) and chronic fatigue syndrome (ME/CFS). However, some research suggests that psychological factors may be a part of MCS as well.

While some in the medical community (and the public) may write off MCS as purely psychological, we have a growing body of evidence showing that it is a physiological illness. The possibility remains, though, that MSC shares underlying pathology with certain psychological illnesses, is especially likely to cause certain psychological illnesses, or is especially likely in someone who already has those illnesses.

Multiple Chemical Sensitivity & Psychological Comorbidities

A 2012 study identified several psychological illnesses in participants with MCS, including:

Researchers stated that psychiatric comorbidities contributed to the functional limitations of people with MCS, as well as their use of the health-care system.

In 2013, a Swedish research team found that people with MCS had high levels of harm avoidance, which is a tendency to avoid things that could cause them problems. They also found physical abnormalities in the areas of the brain that process harm avoidance and concluded that this was a possible pathophysiological basis for the condition.

Is MCS the Cause or Effect?

Knowing that illnesses are linked with each other is just the first step.

It doesn't tell us why -- for instance, do psychological problems lead to MSC, or is it the other way around? Alternatively, do these illnesses have some physical factor in common that makes people susceptible to both of them?

A 2012 study sought to understand more about why MCS and psychiatric disorders so often go together.

Researcher looked into the social consequences of the illness, psychological distress, social support, and major life events. They found that individual experiences such as major life events and social support were not enough to explain the association.

In 2010, research was published that had attempted to gauge whether psychological problems came before or after onset of MCS by collecting data from people without the illness and then following up five years later. The respondents who had developed MCS had started out with more health problems, stress, and strain; were less satisfied with their jobs; had less social support; and tended to recover more slowly than those who'd stayed healthy.

Researchers in this study concluded that the earlier problems may have been signs of sustained arousal, which may have increased people's risk of developing MCS.

MCS may, indirectly, cause some psychological problems. Studies show it can cause social isolation, which can be difficult to cope with. While isolation is a common issue for many people with chronic illness, in MCS interpersonal relationships pose a special problem: anyone who wants to continue being in your life may need to change their hygiene products, laundry detergent and more in order to help you avoid symptoms.

Also, public activities can pose real challenges because of the wealth of chemical agents you may come in contact with, so opportunities for socialization can become limited.

Keep Learning

For more information on MCS, see:


Eek F, et al. Journal of psychosomatic research. 2010 Jul;69(1):9-15. Factors associated with prospective development of environmental annoyance.

Genuis SJ. Clinical therapeutics. 2013 May;35(5):572-7. Chemical sensitivity: pathophysiology or pathopsychology?

Gibson PR, et al. Nursing & health sciences. 2011 Sep;13(3):232-7. Isolation and lack of access in multiple chemical sensitivity: A qualitative study.

Hillert L, et al. PLoS One. 2013;8(1):e54781. Women with multiple chemical sensitivity have increased harm avoidance and educed 5-HT(1A) receptor binding potential in the anterior cingulate and amygdala.

Katherndahl DA, Bell IR, Palmer RF, Miller CS. Annals of family medicine. 2012 Jul-Aug;10(4):357-65. Chemical intolerance in primary care settings: prevalence, comorbidity, and outcomes.

Skovbjerg S, et al. Environmental health and preventive medicine. 2012 Jan;17(1):2-9. The association between idiopathic environmental intolerance and psychological distress, and the influence of social support and recent major life events.

Skovbjerg S, et al. Scandinavian journal of psychology. 2012 Jun;53(3):233-8. Mindfulness-based cognitive therapy to treat multiple chemical sensitivities: a randomized pilot trial.

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