Table of ContentsView AllTable of ContentsDefinitionSymptomsCausesDiagnosisTreatmentAssociated ConditionsCurrent DebateGetting Help
Table of ContentsView All
View All
Table of Contents
Definition
Symptoms
Causes
Diagnosis
Treatment
Associated Conditions
Current Debate
Getting Help
Multiple chemical sensitivity (MCS) is a diagnosis in which exposure to substances like pesticides, industrial fumes, detergent, and petroleum is thought to cause symptoms ranging from headache, fatigue, and muscle pain to shortness of breath, memory problems, and depression.
This article takes a look at symptoms and causes of multiple chemical sensitivity, including how the condition is diagnosed and treated. It also takes an unbiased look at the controversy and the evidence supporting and challenging the diagnosis.
Jose A. Bernat Bacete / Getty Images
What Is Multiple Chemical Sensitivity (MCS)?
Randolph proposed MCS as an intolerance to certain environmental chemicals that lead to chronic, recurring illness and disability. Symptoms of MCS develop based on the types, duration, and severity of the exposure. As such, there isn’t a unique profile as to how MCS “looks.”
While the same can be said of many other diseases with diverse presentations—includinglupus,multiple sclerosis, or psychiatric illnesses—the lack of a clear definition or disease pathway (pathogenesis) has led some to question how to approach MCS in practice or theory.
To avoid dismissing a condition thought to affect a significant portion of the population, the World Health Organisation (WHO) acknowledged the existence of “a disease of unclear pathogenesis” in 1996 and proposed a new entity calledidiopathic environmental intolerance(IEI),
According to the WHO, IEI can be diagnosed based on the following criteria:
Given the broadness of the definition, many practitioners question how useful the WHO criteria are in clinical practice. As a result, some experts have taken a more cause-and-effect approach, defining MCS simply as:
Symptoms of MCS
There are many possible symptoms associated with MCS. They vary significantly from person to person and tend to come on gradually in these two phases:
Regardless of the phase, if a person has MCS, they may experience symptoms such as:
People who have MCS may not experience all of the symptoms mentioned above.
MCS Triggers
What Causes MCS?
The cause of MCS is not well understood because many in the medical community still deny it as a disease entity.
Some research suggests that it could be apsychogenic illnessas many of the symptoms are similar to those seen in mood and psychological disorders, which include:
There is also little evidence to support a physical illness because of a lack of research as well as a lack of concrete findings in the available studies.
Biological Cause TheoriesSome medical professionals theorize that a biological cause may be behind MCS, but currently, these are only theories. Some possible biological causes include:Neurogenic inflammationLimbic systemdysfunctionNeural sensitization and hyperresponsivityImmune system dysregulationOxidative stress
Biological Cause Theories
Some medical professionals theorize that a biological cause may be behind MCS, but currently, these are only theories. Some possible biological causes include:Neurogenic inflammationLimbic systemdysfunctionNeural sensitization and hyperresponsivityImmune system dysregulationOxidative stress
Some medical professionals theorize that a biological cause may be behind MCS, but currently, these are only theories. Some possible biological causes include:
How Is MCS Diagnosed?
Since there are no medical tests to diagnose psychological diseases, these evaluations will primarily focus on a person’s thoughts, feelings, experiences, and behaviors in relation to their symptoms.
Getting the Right DiagnosisIt can be challenging to cope with MCS, especially since the medical community does not recognize it as a disease entity and you may be made to feel as if what you’re experiencing is all in your head. That said, since the disorder is so controversial, it may be difficult to find the proper diagnosis. Diagnosing MCS may require multiple visits to your healthcare provider, tests, evaluations, and second opinions.
Getting the Right Diagnosis
It can be challenging to cope with MCS, especially since the medical community does not recognize it as a disease entity and you may be made to feel as if what you’re experiencing is all in your head. That said, since the disorder is so controversial, it may be difficult to find the proper diagnosis. Diagnosing MCS may require multiple visits to your healthcare provider, tests, evaluations, and second opinions.
How Is MCS Treated?
The medical community is still determining what causes MCS and what is happening within the body to drive symptoms. Because of that, no effective or proven treatments are available specifically for MCS. That said, if a psychological disorder is driving the symptoms, you may be prescribed:
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Other Conditions Associated With MCS
MCS is often associated with other conditions, such asfibromyalgia(FMS),myalgic encephalomyelitis(ME), andchronic fatigue syndrome(CFS). Medical researchers have coined a term for these types of disorders, which is “central sensitivity syndromes.”
These syndromes have many of the symptoms found in MCS, and they are often considered psychogenic as well because it can be hard to pinpoint a physical cause through laboratory tests and examinations.
FMS and ME/CFS as Recognized DisordersWhile MCS is not a recognized disorder, FMS, ME, and CFS are. That is one of the differences between them and MCS.
FMS and ME/CFS as Recognized Disorders
While MCS is not a recognized disorder, FMS, ME, and CFS are. That is one of the differences between them and MCS.
Comorbid Conditions in Fibromyalgia and Chronic Fatigue Syndrome
Why the Debate and Controversy?
A lot of the debate surrounding the existence of MCS and the validity of the diagnosis stems from how the definition has evolved since the 1950s.
From the start, MCS was considered controversial as it was based on a definition of “allergy” that Theron Randolph insisted on but had little to do with howallergies actually develop.
Since that time, MCS has been linked to multiple disorders with equally unclear definitions and causes, includingGulf War syndrome,fibromyalgia,chronic fatigue syndrome (CFS),sick building syndrome (SBS), andelectromagnetic radiation exposure (ERE).
In some cases, the definition of MCS (exposure to usually harmless chemicals) clashed with disorders in which harmful substances were involved.
While much of the evidence is based on various definitions of MCS—some specific and others subjective—this shouldn’t dismiss the fact that a growing number of people are recognizing and reporting illnesses to environmental chemicals that should not be causing illness.
Among the reports:
Opinions are starting to evolve among some treaters who have begun to recognize MCS as a viable—if largely misunderstood—disease entity. In Spain, MCS has been recognized as a disease since 2014 and is listed as a medical condition in that country’sICD-10 (International Classification of Diseases, 10th Revision).
Talk to a Healthcare Provider
Because MCS is so controversial, many people must find their own treatments through trial and error. This process can go much smoother if you find a healthcare provider that works with you on your MCS symptoms without being dismissive of what you’re experiencing.
Before going through specialized treatments that can take time and money or possible renovations in your home to remove chemicals that may trigger symptoms, always seek help from a medical professional.
Be sure to contact more than one healthcare provider, as not all believe that MCS is a physical illness that can be treated.
Summary
The lack of research surrounding MCS has made it difficult to pinpoint a cause. However, many factors can trigger symptoms after exposure to a particular chemical. If you are experiencing the symptoms of MCS but have yet to seek help, contact a healthcare provider. They can assist you in finding out if you have MCS and what you can do about it.
12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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