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Multiple Chemical Sensitivity (MCS) – What Is It?

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MCS – What Is It?

The body is daily exposed to substances which have the ability to damage or even kill it. From an evolutionary point of view, these substances have traditionally included viruses, bacteria, yeasts and fungi, poisonous foods, and other such nasties. The body reacts against these substances via the immune system. The immune system learns to recognize the substances and react against them with inflammation, which effectively kills or denatures that substance.

The problem is that in recent years man has developed a new range of toxic substances, such as pesticides and solvents. These chemicals are equally toxic to the body and the body recognizes this. To cause damage the chemical either has to be particularly toxic or present in a high concentration, and this appears to switch on the immune mechanism for identifying and reacting against chemicals.

Everybody knows that once you have had measles you are protected against future attacks because the immune system has learned to recognize the measles virus and attacks it vigorously before the numbers can build up and cause an infection.

Exactly the same principle (but possibly a different mechanism) applies with chemical sensitivity. Once the body has been damaged by an overwhelming dose or a toxic dose of a chemical, the body learns to recognize very tiny amounts of this chemical and reacts against it accordingly. This is probably the first step in developing chemical sensitivity.

The ‘Spreading Phenomenon’

However, chemicals are often related – and the next step which happens is that the body then starts to react against other, related chemicals. This is called the spreading phenomenon and results in multiple chemical sensitivity, whereby one reacts to lots of different chemicals.

The body has more than one line of defense. The immune system is just one, but we are intelligent beings and just as one might choose to avoid spending time with somebody who has got influenza, one also chooses to avoid inadvertent exposure to chemicals.

The presence of these chemicals can often be sensed by smell, and the body quickly learns that smelling a substance will subsequently result in severe symptoms. Indeed this quickly becomes a conditioned response (just as with Pavlov’s dogs), whereby just the smell of a chemical will induce the symptoms.

So multiple chemical sensitivity is:

  • An acquired sensitivity to chemicals
  • Which may be noxious initially, but often innocuous subsequently,
  • Which is triggered by a tiny exposure to a chemical,
  • Which may result in a multiplicity of symptoms,
  • Which may take hours or even days to clear.

A Matter of Degree

There are many degrees of multiple chemical sensitivity. In a random telephone survey of United States citizens, it was shown that 7.8% of the population said that they were intolerant of certain chemicals and avoided them.

Many people will tell you that:

  • Perfume makes them sneeze,
  • Petrol fumes cause nausea,
  • Alcohol makes them feel spaced out and dizzy,
  • Paint fumes may cause headache.

These are the minor and easily avoidable chemical incitants. However, for some people their sensitivity is so severe that they are unable to tolerate even the slightest exposure to chemicals, as a result of which they have to live in carefully controlled clean environments. The slightest exposure to chemicals causes severe symptoms and they are simply unable to go into an uncontrolled environment.

These people are made prisoners in their own home, being unable to go out into cars, travel into any public place, or meet other people who may be wearing the very cosmetics, perfumes and fabrics which make them ill.

MCS – What are the Symptoms?

Multiple chemical sensitivity is the great mimic. It can produce almost any symptom. In her paper "Toxicent-Induced Loss of Tolerance" [TILT], Professor Claudia S. Miller, MD [a leading chemical exposure and sensitivity expert at the University of Texas Health Science Center] gives the following list of general symptoms:

Neuromuscular; Cardiac; Loss of consciousness; Heart pounding; Stumbling/dragging foot; Rapid heart rate; Seizures; Irregular heart rate; Print moving/vibrating on page; Chest discomfort; Feeling off balance; Affective Tingling in fingers/toes; Feeling tense/nervous; Double vision; Uncontrollable crying; Muscle jerking; Feeling irritable/edgy; Fainting; Depressed feelings; Numbness in fingers/toes; Thoughts of suicide; Clumsiness; Nerves feel like vibrating; Problems focusing eyes; Sudden rage; Cold or blue nails/fingers; Loss of motivation; Uncontrollable sleepiness; Trembling hands; Head-related: Insomnia; Head fullness/pressure Airway: Tender face/sinuses; Cough; Sinus infections; Bronchitis; Tightness in face/scalp; Asthma or wheezing; Brain feels swollen; Post nasal drainage; Ringing in ears; Excessive mucus production; Headache; Shortness of breath; Feeling groggy; Eye burning/irritation; Musculoskeletal; Susceptible to infections; Joint pain; Dry eyes; Muscle aches; Enlarged/tender lymph nodes; Weak legs; Hoarseness; Weak arms; Cognitive; General stiffness; Memory difficulties; Cramps in toes/legs; Problems with spelling; Painful trigger points; Slowed responses; Gastrointestinal; Problems with arithmetic; Abdominal gas; Problems with handwriting; Foul gas; Difficult concentration; Problems digesting food; Difficulty making decisions; Abdominal swelling/bloating; Speech difficulty; Foul burping; Feelings of unreality/spacey; Diarrhoea; Other Abdominal pain/cramping; Feeling tired/lethargic; Constipation; Dizziness/lightheadedness.

My experience is that:

  • The most common systemic symptoms are foggy brain (inability to think clearly), headache, fatigue and dizzy spells.
  • The most common local symptoms are rhinitis (runny nose), conjunctivitis (itchy eyes) and asthma.

MCS – Who Gets It?

Multiple chemical sensitivity can occur in anybody, but very often there is some overwhelming exposure to a toxic substance which triggers it in that person. The groups of workers with well documented chemical sensitivity following occupational exposure are as follows:

  • Gulf war veterans;
  • Homeowners exposed to pentachlorophenol wood preservatives;
  • Homeowners/Office workers exposed to organophosphate/carbamate pesticides;
  • Hospital workers;
  • Sheep dippers exposed to organophosphate pesticides;
  • Radiology workers exposed to film developing chemicals;
  • Solvent-exposed workers;
  • Office workers and teachers (various indoor air exposures) – otherwise known as sick building syndrome;
  • Homeowners/office workers exposed to volatile organic compounds associated with remodeling – such as new carpets, new paint and new office furniture;
  • Casino workers exposed to mixed pesticides;
  • Implant recipients;
  • Chemical weapons production workers;
  • Agricultural workers exposed to organophosphate pesticides.

In all these cases there has been excessive exposure to chemicals with MCS resulting. It is quite clear from inspection of these lists that the reason MCS is denied by the establishment is because all these illnesses are caused by exposures in the workplace. To admit that MCS exists and is as a result of these exposures would result in major litigation.


* * * *

Note: For further information on chemical sensitivities and coping with MCS, see for example:

n (For UK residents) Dr. Myhill’s listing of physicians practicing “Ecological Medicine” (allergy, environmental, and nutritional medicine).

n Other articles by Dr. Myhill on many topics relating to sensitivities/allergies, symptoms, detoxification, and tests (

n The Environmental Illness Resource (EIR) website. It offers a variety of resources including:

1. A collection of articles, the most visited being “Multiple Chemical Sensitivity – The End of Controversy” by Martin Pall, PhD – author of the groundbreaking new book Explaining Unexplained Illnesses.

2. Information about MCS-related tests, including info on two labs offering the particular blood test that Dr. Myhill describes – the Chemical (Lymphocyte) Sensitivity test. The two labs are Biolab Medical Unit ( in the UK; and Immunosciences Lab, Inc. ( in California. BioLab has provided an illustrative sample report on the Lymphocyte Sensitivity Test. It indicates probable sensitivity levels for a variety of substances, as selected by the referring physician.

* This material is reproduced with permission from Dr. Sarah Myhill’s patient-information website ( R Sarah Myhill Limited, Registered in England and Wales: Reg. No. 4545198. Dr. Myhill is a UK-based physician known for practicing a combination of conventional and holistic medicine, with special interests in prevention, diet/nutrition, and fatigue.

Note: This information has not been evaluated by the FDA. It is generic and is not meant to prevent, diagnose, treat, or cure any illness, condition, or disease. It is essential that you make no decision about additions to or changes in your healthcare plan or health support regimen without first researching and discussing it in collaboration with your professional healthcare team.

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4 thoughts on “Multiple Chemical Sensitivity (MCS) – What Is It?”

  1. lisanagy says:

    I am a physician treated in dallas by Bill Rea for Chemical Sensitvity (we no longer use the term MCS here) and I have spoken to hundreds of families who have suffered from mold exposure leading usually the wife to become chemically sensitive. Over half of the patients by Bill in the clinic have started off their downhill course with a mold exposure (such as a musty basement).

    1. cltatum says:

      I too have a chemical sensitivity. After being tested by a local ortholarangologist, allergist, ENT,etc.; I was told I had the chemical problem and given an option of sublingual drops for desentitizing. These drops were made for me and used under the tongue daily. My insurance company paid for the drops and testing. I used them for a year with very good results, after buildup to maintenance level, and continuation. Next my physician stopped taking insurance and I had to stop the treatment, due to financial strain. I must say I am better than before, but some of the symptoms have returned, due to stopping them too soon. They work like allergy shots and need to be continued. There isn’t a lab or physician that does this within 100 miles of my home. I contacted our insurance company and received a letter stating that this treatment was controversial and could not be continued with the physician on an insurance approval. Instead of trying to change this decision, I opted to quit the treatment. A big mistake was made. I also have Fibro, CFS, and do not feel the quality of life that I had while on the drops. So sad for me to give up and also out of character. Due to many other issues with my family health, I choose to ignore mine and now we all suffer because of my decision. Anyone interested in this wonderful physician can e-mail me for his name and location. Also you may call: “Genesis (as in the bible) ENT & Plastic Surgery, 14835 John J. Delaney Drive, Suite 210, Charlotte, NC 28277 704-544-1300 for more information. Dr. Drago is simply wonderful and understanding. He also performed surgery for my husband’s ENT problems and made a huge difference in his life. Good luck out there.

    2. PluckySickOne52 says:

      I am so glad that ProHealth has recognized and included MCS in its discussions. I was first diagnosed with MCS by George Kroker, MD, in LaCrosse, WI in 1986. His clinic saved my life. I’ve been experiencing symptoms of FM and CFIDS all that time also, but managing OK: able to work and continue being an athlete. However, in the past six years, mold, family stress and financial difficulties have caught up with me. I am now very ill, financially destitute, waiting for Fed. gov’t help (yeah, right).
      Hang in there EVERYONE. We need to help us help us all. Look at ,,
      Be as well as possible, keep in touch.

  2. brainfart says:

    I have severe MCS and also fibromyalgia, IBS, endometriosis, uterine fibroids and massive allergies.All of this is toxin related. I have been given the run-around by the medical community for over 4 years now. Not only are you incredibly sick and have no quality of life, you also have to fight for this illness to be recognized by doctors. Finally, after struggling for nearly 12 years I was diagnosed by 2 doctors – one a specialist for FM and MCS.
    There are NO accomodations for individuals with MCS in hospitals in Canada, so if you get sick you have a problem. I was pushed over the edge by an anesthetic given to me for a laparoscopic procedure and my life has not been the same since. I actually had to threaten doctors that I would sue them in order to be treated carefully after that. Even that was not enough. I tried to communicate with my local hospital to set up a care plan in case I could not advocate for myself and was rebutted and ignored. I have medicalert, but most of the time they don’t even look at my bracelet. That is scary!
    Anyways, the way individuals with MCS are being treated borders on neglect – all to cover up for the mighty dollar. Pharmaceutical and Petrochemical Companies run the show and for them to admit that some of us may be harmed by their practices is impossible. I have also been seriously harmed by pesticides, yet my neighbor is allowed to spray his lawn so it’s pretty. What’s more important here I wonder – a human being or a lawn?
    The worst about it all is that I cannot take drugs that would ease my pain. I had to learn to use my mind to control my pain, which has helped me tremendously.
    I am sadened by the lack of compassion and caring that is extended to patients with MCS. There are no clinics to go to that are publically funded and most sufferers live at the poverty line because they have lost their jobs and are unable to work. It is also extremely difficult to get disability due to MCS. The world has a long ways to go and if no changes are made in how we look at the chemicals in our environment this illness will take on epidemic proportions in the near future.
    I feel terribly helpless, because my basic needs for clean, fresh air, unpolluted water and nourishing food are not met anymore. I cannot walk outside because the dryer fumes emitted by everyone’s liberal use of fabric softeners and scented laundry soaps are giving me severe symptoms, which cannot be treated with drugs. Shopping is a nightmare, because even in grocery stores there are scented candles and sometimes even weedkillers and poisons right next to bread and other staples that can absorb the fumes. When I get home..and this is after wearing a mask…my body usually burns real badly for a day or so. I can get instant diarrhea, but mostly I get horrible pain in my muscles, which ceases when I stay inside my house with my $800 aircleaner. Basically, I am toxic. My bucket is full. What was diagnosed as FM was just the start for me. It was mild MCS and had I avoided chemicals back then I would have been better off. But I did not know. Please listen to me. It may save your life. Go organic, use environmentally friendly cleaners and so on.
    I plead to everyone to consider changing the way we live NOW. Before it’s too late!

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