Multiple Chemical Sensitivity Syndrome

The multiple chemical sensitivities (MCS) syndrome is a subjective illness in which various symptoms are blamed on various environmental chemical exposures. Symptoms are often vague and include fatigue, muscle pains, nausea, and memory loss. No diagnostic physical or laboratory findings completely define the illness.

Stressed businessman

Jon Feingersh / Blend Images / Getty Images

This syndrome has been given many other names, including idiopathic environmental intolerance, chemical sensitivity syndrome, total allergy syndrome, 20th-century disease, cerebral allergy and universal allergy.


Since symptoms can vary from one person to another, there is no set of defined criteria for MCS syndrome. However, MCS syndrome appears to occur more commonly in adults, and primarily in women.

People affected by MCS syndrome describe symptoms in relation to environmental exposures, especially odors. Most commonly, the sources of these odors include perfumes, scented products, solvents and cleaning agents, new carpet, car exhaust, air pollution, plastics, formaldehyde, and cigarette smoke.

Other people with MCS are affected by various foods, food additives, medications, and mercury in dental fillings. More recently, MCS syndrome has been blamed on silicone breast implants and has been associated with the Gulf War Syndrome.

No studies have shown that higher doses of the above triggers are more likely to cause symptoms in people with MCS syndrome. There are also no studies that prove toxicity of the triggers as a cause of symptoms.

Possible Causes

Various theories have been proposed as a cause of the MCS syndrome. These have included immunologic, toxicologic, psychologic, and sociologic theories.

Some experts related the cause of MCS syndrome to an autoimmune or immunodeficiency causes, triggered by chemicals in the environment. There are no studies to support such a theory.

Another theory, called the neurotoxic theory, relates symptoms to stimulation of the olfactory (sense of smell) system of the brain. Other theories related to toxicity of the odors, foods, and medications, and relate to some people as having “overly sensitive” mucous membranes.

Lastly, MCS syndrome has been proposed as a psychiatric or personality disorder and is often associated with or attributed to panic attacks.


The MCS syndrome is diagnosed by a person’s history of symptoms with exposure to various chemical triggers. There are no defining criteria for this illness, and typically no physical or laboratory findings to which the disease can be attributed.

However, some practitioners will attempt to perform testing, such as neutralization-provocation, in an attempt to identify triggers. There is no scientific basis for these various tests.


If psychiatric disease is suspected as contributing to MCS, a psychotherapeutic approach may be prescribed, which could include medication and/or psychotherapy. In other cases, avoidance measures may be recommended.

Want to keep learning? Find out more about alternative therapies for the treatment of allergic diseases.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Magill MK, Suruda A. Multiple chemical sensitivity syndrome. Am Fam Physician. 1998;58(3):721-728.

  2. Johns Hopkins Medicine. Multiple chemical sensitivity.

  3. Barsky AJ, Borus JF. Functional somatic syndromes. Ann Intern Med. 1999;130(11):910-921. doi:10.7326/0003-4819-130-11-199906010-00016

Additional Reading
  • AAAAI Board of Directors Position Statement. Idiopathic Environmental Intolerances. J Allergy Clin Immunol. 1999;103:36-40.
  • Das-Munshi J, Rubin GJ, Wessely S. Multiple Chemical Sensitivities: A Systematic Review of Provocation Studies. J Allergy Clin Immunol. 2006;118:1257-1264.

By Daniel More, MD
Daniel More, MD, is a board-certified allergist and clinical immunologist. He is an assistant clinical professor at the University of California, San Francisco School of Medicine and currently practices at Central Coast Allergy and Asthma in Salinas, California.