Multiple Chemical Sensitivity, a Health Challenge - Step To Health

Multiple Chemical Sensitivity, a Health Challenge

Multiple chemical sensitivity is a rare condition that's difficult to diagnose. Also, some professionals don't even consider it a disease. Learn more in this article.
Multiple Chemical Sensitivity, a Health Challenge

Last update: 16 October, 2021

Multiple chemical sensitivity has other scientific names that relate to its extreme allergic symptoms. The most accepted terminology in the scientific environment is idiopathic environmental intolerance

In itself, it’s a chronic condition related to allergic reactions. The patient responds in an excessive way to small concentrations of substances that are usually found in the environment.

The substances must be chemical; therefore, it constitutes a topic of discussion in occupational medicine. Some laws recognize it as an occupational disease, but others do not.

For a while, scientists classified it as a psychosomatic invention. Even today, some doctors don’t recognize it as a disease and attribute it to an excessive manifestation of the psyche of people.

People with multiple chemical sensitivities are estimated to represent less than 1% of the general population. However, about 10% of people suffer from some type of allergy. 

The diagnosis is very difficult. There’s no laboratory test to certify multiple chemical sensitivity. Your doctor may suspect it, request allergy panels as a complementary test, and diagnose it based on these findings.

Pathophysiology of multiple chemical sensitivity

The origin of this disease is unknown. Scientists have yet to publish studies that unravel the mechanisms that lead to exaggerated allergic reactions at such low concentrations of the substance.

The most well-founded hypothesis stipulates that the person comes into contact with a chemical agent for the first time and their immune system reacts poorly. Then, the memory of the reaction remains in the body and they only need a small dose to trigger the symptoms. 

Another hypothesis is similar, but gives more weight to the person’s loss of tolerance. In other words, after a first encounter with the chemical, the body doesn’t get used to it. Instead, the body becomes hypersensitive to it. 

This multiple chemical sensitivity finds stimulation in the limbic system of the nervous system. The substance’s stimulus may disappear, but the body sends out immune response signals with nothing concrete to attack.

So, the described mechanism resembles that of diseases like fibromyalgia or irritable bowel. Scientists suspect that there’s a pathophysiological link between these conditions. 

A woman with allergies.

Symptoms of multiple chemical sensitivity

The signs and symptoms of this disease are very varied. Almost all organs can manifest when there’s an acute reaction, making it even more difficult to identify.

The most common symptoms are those related to the respiratory system. For example, you could experience an itchy throat, dry cough, or a runny nose. Also, you may experience digestive system issues, like nausea, vomiting, and diarrhea. 

In addition, you may experience the symptoms of allergic conjunctivitis in your eyes, like lacrimation and red-eye. Also, the heart may accelerate its heart rate and cause palpitations.

It’s common for a person with multiple chemical sensitivities to end up being diagnosed with asthma or irritable bowel. However, doctors often overlook this rare and truly disorienting condition. 

Also read: Dust Mite Allergy

Diagnostic criteria

Types of allergic conjunctivitis

There are two things doctors can use to diagnose multiple chemical sensitivity:

One of them is to use widely recognized, but general criteria. They imply that the patient must comply with the following:

  • Have symptoms every time you are exposed to the substance in question.
  • Chronic evolution.
  • The disappearance of symptoms from time to time, with intervals without allergic signs.
  • Multiple involvement of tissues and organs at the same time. 

The other is to use the QEESI questionnaire: this is an instrument that measures the degree of difficulty the patient has with the disease. It measures this through patient questions. Based on the score the patient gets, the doctor can classify the severity.

Professionals treating fibromyalgia also use the QEESI questionnaire as an evaluation tool. This reinforces the idea of the connection between these diseases. 


At the beginning of this article, we said that multiple chemical sensitivity is a problem in the world of work. In this sense, it’s difficult for companies and insurers to recognize it as an occupational disease. 

However, it’s worth asking what doctors can do for a person who suffers from it and has to be exposed to powerful chemicals for their work. This is a situation that doesn’t have a simple solution, especially when it comes to a disease that isn’t always accurately diagnosed. 

Meanwhile, scientists will continue to study the disease to try to clarify any doubts about it. They may create a test to diagnose this condition in the near future. 

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