Multiple Chemical Sensitivity, or MCS, also goes by other names such as Chemical Injury, Chemical Sensitivity, Environmental Illness or EI, and Multiple Allergy. What it is, basically, is an extreme reaction to every day pollutants such as smoke, perfumes, cleaning products, gasoline, scented candles, and many others.
The difference between this and other allergies is that there is no known cause, but for the people who suffer from it it is a very real and debilitating disease. Symptoms include burning or stinging eyes, shortness of breath, breathing difficulty, nausea, extreme fatigue, memory and concentration problems, headache, vertigo, migraine, runny nose, sore throat, cough, sinus problems, skin rashes, sensitivity to light and/or noise, muscle and joint pain, digestive upset, and sleeping problems. Sounds like many auto-immune diseases, which is part of the trouble with diagnosis.
Because symptoms and triggers vary widely from person to person, traditional medicine is often ineffective, avoidance is often the only option. With MCS the problem is chronic, not a one-time occasion, and can be caused by a process known as conditioning. In conditioning, a person who is already sick, or already has a headache, and is then exposed to a strong odor of say, gasoline, every time that person smells gasoline can produce the initial symptoms of headache or nausea. With MSC the person must have many triggers, and the same effect should be produced by each one, gasoline should always produce a headache, lavender perfume should always produce shortness of breath, certain soaps should always cause skin irritation, etc.
This is a very complicated condition, one that even doctors have trouble finding a good remedy for. Research continues to be done, and more articles will follow.