Idiopathic Environmental Intolerances

September 14, 2011

Idiopathic environmental intolerances (IEI), previously called multiple chemical sensitivities, is also known as environmental hypersensitivity (allergy) or environmental illness. Idiopathic Environmental Intolerances is an acquired condition in which a person repeatedly notices symptoms that seem triggered by exposure to a certain chemical substance(s) in amounts that are usually well tolerated by most people.


Idiopathic Environmental Intolerances is diagnosed mostly in adult women. Whether the condition is due to environmental exposure or a psychological disorder is controversial. No currently identified medical abnormalities explain why Idiopathic Environmental Intolerances occurs. Current theories include toxins leaking through the respiratory tract, toxins affecting the nervous system, or toxins affecting the immune system.

The list of environmental chemicals that may cause symptoms is very long. Many people with Idiopathic Environmental Intolerances are affected by smells, including any type of pollution, fumes, fragrances, or chemicals either in the house or workplace. Other possible triggers include certain foods, food additives, medications, electromagnetic fields, and mercury in dental fillings. There is no clear relationship between the symptoms reported and the known toxic effects of the specific chemicals. The symptoms occur at concentrations of the chemicals well below those expected to cause toxicity.

There are no symptoms that are diagnostic of Idiopathic Environmental Intolerances. The most common symptoms include malaise, tiredness, sweating, nasal congestion, sore throat, hoarseness, cough, shortness of breath, chest pain, chest tightness, palpitations, nausea, abdominal pain, passage of a large volume of urine, joint aches, back pain, muscle aches, dizziness, headache, impaired thinking, poor memory, difficulty concentrating, tremor, tingling, anxiety, and irritability. Psychological reactions to Idiopathic Environmental Intolerances may include stress, anxiety, and panic at the thought that environmental exposure may have occurred. Patients may go to great lengths to avoid exposure to their triggers.

Physical examination and laboratory tests are not generally helpful. Measurements of environmental chemical levels or imaging studies do not help make the diagnosis. Because there are no diagnostic guidelines for Idiopathic Environmental Intolerances, the evaluation of a person with symptoms of Idiopathic Environmental Intolerances should include a medical history and physical examination and an evaluation of the environment. Treatable conditions should be ruled out. Overuse of diagnostic tests should be avoided.

Other diagnoses that may be considered include somatoform or conversion disorders, chronic fatigue syndrome (CFS), sick building syndrome (SBS), and fibromyalgia. Other possibilities include allergens, infectious microorganisms, irritants, and toxins.

The condition may develop slowly with a single environmental, or occupational trigger. Eventually the patient attributes a growing number of symptoms to an increasing number of common chemical stimuli under ordinary conditions. The person’s occupational function and social life are often affected by Idiopathic Environmental Intolerances. Although Idiopathic Environmental Intolerances is not life threatening, it can be distressing and functionally disabling.

Some individuals with Idiopathic Environmental Intolerances have an underlying or concomitant psychiatric disorder that, when diagnosed,
responds to medication. Avoiding exacerbating exposures should be considered. Prescription of unnecessary dietary, environmental, or occupational restrictions should be avoided.

There is no evidence from clinical studies that any treatment is effective. Some treatments can make the condition worse. Avoidance regimens can be extreme. Vitamin and mineral supplementation is not proven to help. Some other treatment programs include intravenous gamma globulin (to boost the immune system), or giving chemical and food extracts either by injection or oral drops to “neutralize” the reaction. None of these treatments are proven to be effective or safe.

SEE ALSO: Autoimmune disorders, Fibromyalgia

Suggested Reading

  • American Academy of Allergy, Asthma, and Immunology (AAAAI) Board of Directors. (1999, January). Idiopathic environmental intolerances. Journal of Allergy and Clinical Immunology, 103 (1 Pt. 1), 36-40.
  • Staudenmayer, H. (2001, March 31). Idiopathic environmental intolerances (Idiopathic Environmental Intolerances): Myth and reality. Toxicology Letter, 120(1-3), 333-342.

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