People with multiple chemical sensitivity (MCS) are made sick by exposures to low levels of many common chemicals – such as perfume, pesticides, tobacco smoke, fresh paint, new carpets, air “fresheners,” new building materials, vehicle exhaust, solvents, industrial fumes, and many cleaning products.  Many of these chemicals can make anyone sick at high levels, but chemically sensitive people can become extremely ill after exposures to even minute amounts of these substances.  Reactions can occur after chemicals are inhaled, ingested, or absorbed through the skin.  Chemically sensitive people also frequently react to foods, drugs, mold, pollen, and electromagnetic fields.

MCS Symptoms

The symptoms of MCS are diverse and unique to each person.  Symptoms range from mild to life-threatening and include, but are not limited to, headache, trouble concentrating, nausea, vomiting, diarrhea, fatigue, weakness, metallic taste in mouth, dizziness, numbness and tingling, wheezing, irregular heartbeat, joint and muscle pain, tremors, and seizures.  Altered brain chemistry may also cause anxiety, depression and emotional outbursts.  Symptoms in children include red cheeks and ears, dark circles under the eyes, hyperactivity, and behavior or learning problems. After an exposure, symptoms may occur immediately or be delayed by hours or days.  Reactions may last from a few minutes to weeks or months.

Who Gets MCS?

Many people who become chemically sensitive were once healthy individuals who tolerated chemical exposures like everyone else, until they had an exposure from which they did not recover.  For example, people have developed MCS after moving into a newly built house, having carpets installed in their office, or after having their home sprayed with pesticides.  Others slowly become ill over a period of years, seemingly as a result of the cumulative exposures of everyday life.

Reports from around the world indicate that chemical sensitivity is a global problem.  MCS occurs in people of all ages, races, and economic backgrounds.  It occurs twice as often in women as in men.  A national U.S. prevalence study found 11.2% of respondents reported a heightened sensitivity to common chemicals, and the numbers seem to be growing.

How is MCS Diagnosed?

A published consensus definition defines MCS as a chronic condition involving multiple organ systems in which low-level exposures to multiple chemically unrelated substances cause symptoms, and these symptoms improve or resolve when a person is no longer exposed to these substances.  

The key factor distinguishing MCS from other medical conditions is that MCS symptoms come and go, or wax and wane, in relation to levels of chemical exposures that do not ordinarily affect others.

People with MCS frequently have imbalances in their nervous, immune, and hormonal systems, as well as impaired detoxification abilities.  Some chemically sensitive people may appear normal, while others may appear quite ill.  A physical examination may reveal the presence of a rash, yellowish or pale skin, swollen hands or feet, wheezing, irregular heart beat, trouble speaking and communicating, swollen lymph nodes, poor coordination, or tremors.  Lab tests that are frequently abnormal in people with MCS include SPECT brain scans, in-depth immune studies, and elevated levels of heavy metals or synthetic chemicals.

How is MCS Treated?

There is no known cure for MCS, but a variety of treatments can help people reduce their symptoms and improve their health.  The most helpful treatment is to avoid exposures to chemicals, foods, drugs, and electromagnetic fields that trigger symptoms.  A good place to start is to create a “safe” room in one’s home that is as free of triggering substances and conditions as possible.

Other treatments used to help people with MCS include nutritional supplements, digestive aids, hormone balancing, detoxification, desensitization, eliminating occult infections, oxygen, and immune stimulation.  Acupuncture, homeopathy, herbs, brain retraining programs and other alternative/complementary treatments have also helped some chemically sensitive people.  It should be noted, however, that people with MCS vary considerably in their response to treatments and their ability to tolerate them (with the exception of chemical avoidance, which is almost universally helpful).

Chemically sensitive people are advised to find a physician who is knowledgeable about MCS, in order to avoid getting sick in standard medical offices, being misdiagnosed, put through inappropriate or hazardous testing and treatment, and suffering from disbelief or even hostility from medical staff.  Many medical doctors who specialize in the evaluation and treatment of MCS can be located through the American Academy of Environmental Medicine, 316-684-5500,

Full recovery from MCS is rare.  Most people experience a chronic relapsing course with periods of improvement alternating with periods of setbacks.  Few people die from MCS, but deaths have been known to occur as the result of suicide, asthma, severe malnutrition and the inability to tolerate treatments for cancer, infections, and other serious illnesses.

Impact of MCS

People with mild to moderate chemical sensitivities may be able to make adjustments in their diets, home environment, type and location of work, clothing, and personal care products they use to remain productive and connected to the outside world.  At its worst, however, MCS is a severe, disabling, and isolating disease that forces people to alter every aspect of their lives.  People with severe MCS often lose their jobs, home, careers, family and friends.  They are unable to go into most buildings and some become homebound.  The isolation imposed by chemical barriers and lack of understanding of MCS contribute to the often devastating nature of this illness.

MCS Politics

The acceptance of MCS as a “real” illness by the medical community has been slow, and still has a long way to go.  This is largely the result of the extensive efforts of the chemical/pharmaceutical industry to prevent the recognition of MCS.  Manufacturers of pesticides, perfumes, carpets, scented cleaning products, paints, building materials and many other products could suffer large economic losses, resulting from lawsuits and diminished sales, if it became generally accepted that exposure to their products can make people sick.  They would rather silence the messenger than heed the message of chemically sensitive people that many consumer and building products are not safe.

Despite industry efforts, the validity of MCS continues to slowly gain ground.  MCS is recognized as a potentially disabling condition by the Social Security Administration, the U.S. Department of Housing and Urban Development, and an increasing number of other federal, state, and local government agencies.  People with MCS are covered under the Americans with Disabilities Act on a case-by-case basis, like all other people with disabilities.

MCS Future

People with MCS continue to organize locally, nationally, and internationally to educate others about this disease, promote research, advocate for those who suffer from it, and help prevent others from getting it.