What are chemical sensitivities?

Chemical sensitivities means when a person experiences reactions (such as brain fog, headache, rash, shortness of breath and/or difficulty breathing, agitation, anxiety to name only a few) when they are exposed to certain chemicals or substances. They are physically sensitive to these chemicals.

Being sensitive to chemicals comes under the heading of Environmental Illness (EI). EI is an overarching term used to describe the illnesses and diseases that some people have whose symptoms and reactions occur or worsen when they are exposed to chemicals or substances in the environment (the external—both indoors and outside—environment, on other people, and on themselves.)

In an EI, something in the environment is toxic, and/or an irritant, or incitant and can cause individuals to have mild to severe and life-threatening reactions from their exposure to the chemical or substance—even exposure to the tiniest amount that another person might not even notice.

What is MCS?

Multiple Chemical Sensitivity (MCS) is a term used to name the experience of being chemically sensitive to multiple substances and having mild to severe and/or life-threatening reactions to those substances.

Individuals who have sensitivities to multiple chemicals are suffering from an Environmental Illness (EI).

Current research (see T.C. Theoharides, MD, here and here) has shown that the reactions to the triggers individuals with chemical sensitivities experience have their basis in mast cell function and in mast cell degranulation. Click/Tap here to learn more about mast cells.

Are chemical sensitivities a mental illness?

Experiencing sensitivity to multiple chemicals (and the reactions that a person can have) is not a mental illness. EIs are real, physiological illnesses not psychological.

The impact and effects of chemical sensitivities on a person and on their life can be devastating. People do not always know or even realize that what they are experiencing has a name. Most physicians are not trained to recognize, diagnose, or treat chemical sensitivities and environmental illnesses. Many healthcare professionals deny they exist.

What can someone do to not become worse?

People with sensitivities to multiple chemicals must avoid and minimize their exposures to the chemicals and environments that cause them to have what can often be severe and potentially life-threatening reactions. Individuals with chemical sensitivities may need to avoid small and large groups of people, public places (like libraries, buses, trains, offices, parks, restaurants,) car exhaust, certain foods, cell phones, soaps and detergents, electrical currents, plastics—and this is not a complete list of all the triggers. Chemical sensitivities can be permanently disabling for some while others are able to continue working once reasonable accommodations are in place.

I don’t understand about triggers.

The word ‘trigger’ refers to whatever chemical or substance it is that makes a person with chemical sensitivities have a reaction. The specific triggers that cause a reaction, as well as the reactions themselves, can be different for different people.

Many times individuals who have chemical sensitivities will wear face masks with activated charcoal filters to decrease their exposure to the chemicals in the environment. It is important to remember that in order to receive medical care, a person with chemical sensitivities must intentionally put themselves into an environment, (the doctor’s office, hospital, clinic, health center, private practice office,) that has the potential to cause them permanent, irreversible harm and damage while making them very, very ill with their reactions in the process.

What about scented products?

A person who has chemical sensitivities has reactions to multiple chemicals and substances. If a product is scented, it isn’t the scent to which a person reacts. The person is reacting to the chemicals (and many times to the “natural” and/or to the “organic”  substances, as well) that the product contains which combine to create a scent. They are not reacting to the smell.

An example of this is laundry detergent. It can be easy to think, after being exposed to the strong scent of a certain laundry detergent and having a reaction, that it was the “scent” causing the reaction when really it was the chemicals and substances that make up the laundry detergent and the chemicals and substances that make up the scent that triggered the reaction.

This is why people are sometimes puzzled when they still have a reaction but have switched laundry products to one without fragrance—why are they still reacting? It’s because it isn’t the “scent” that causes the reactions. It’s the chemicals and substances that make the product and the chemicals and substances that create the scent that are the triggers. It is to these chemicals and substances that people have reactions.

What do I do?

If you feel that you may have chemical sensitivities, MCS, or another EI, contact a physician to receive medical help. The information presented here is not medical advice and is in no way a substitute for receiving medical advice and treatment from a doctor.

Learn More:

About Chemical Sensitivities



About EIs

Toxins in our Lives

Pesticide Information





Education & Training

The Counseling Center at CELA is not endorsing any of the above links or their content and is providing these links as informational resources only.