Idiopathic environmental intolerance (IEI) is a set of symptoms caused by contact with some kinds of substances. It used to be known as multiple chemical sensitivity (MCS). People with IEI have symptoms when exposed to low levels of common substances. Symptoms can include fast heart rate, sweating, and feeling dizzy.
Researchers are doing studies to learn the causes of IEI. It is not an allergic reaction. It does not cause the release of chemicals by the immune system. The physical cause is hard to find. Because of this, some studies suggest IEI may be linked to psychiatric disorders. These include somatoform disorders, depression, and anxiety. IEI occurs more in women than in men. IEI happens more often in people in their 30s or 40s.
Substances that cause symptoms are called triggers. These may be synthetic or natural substances. Triggers can include:
Caffeine
Food additives
Carpet and furniture
Plastics
Perfumes and other scented products
Paint
Cigarette smoke
Smoke from wood-burning stoves
Inhaled ozone and nitrogen dioxide
Inhaled sulfur dioxide
Dust storms, forest fires, volcano ash
Vehicle exhaust, petroleum refining, fossil fuel combustion
Cleaning fluids
Pesticides and herbicides
People with IEI may have symptoms such as:
Increased heart rate
Chest pain
Sweating
Shortness of breath
Fatigue
Dizziness
Warmth and redness of the face and neck (flushing)
Treatment for IEI may include:
Staying away from triggers
Counseling that may include cognitive-behavioral therapy (CBT)
Medicines for some symptoms