What is Multiple Chemical Sensitivity

What is Multiple Chemical Sensitivity

Multiple Chemical Sensitivity – also referred to as MCS – is also known as Chemical Injury, Chemical Sensitivity, Environmental Illness (E.I.), and Multiple Allergy…

Multiple Chemical Sensitivity; in broad terms it means an unusually severe sensitivity or allergy-like reaction to many different kinds of pollutants including solvents, VOC’s (Volatile Organic Compounds), perfumes, petrol, diesel, smoke, “chemicals” in general and often encompasses problems with regard to pollen, house dust mites, and pet fur & dander.




Multiple chemical sensitivity unlike true allergies – where the underlying mechanisms of the problem are relatively well understood widely accepted, is generally regarded as “idiopathic” – meaning that it has no known mechanism of causation & it’s processes are not fully understood.

The problem here is made more difficult still, due to the variable nature of Multiple Chemical Sensitivity from one patient to the next & this often makes treatment with conventional medicine & practices ineffective or inappropriate; for most sufferers with Multiple Chemical Sensitivity, the avoidance of pollutants/toxicants is the key.

What CAN be said about defining Multiple Chemical Sensitivity – and in order to help the patient decide whether they truly have MCS or another allergy-related illness – is that the following deciding criteria apply to Multiple Chemical Sensitivity:

the patient exhibits problems – often an allergy-like reaction – to both large – often extremely low levels of irritants/toxicants/triggers : other individuals present at the same time may be unable to detect anything at all or anything unusual or out of the ordinary.

  • the problem is ongoing, ie. chronic, and not a “one-off” event.
  • the same symptoms are reproducible with repeated exposure to the same triggers.
  • the patient is affected by many different triggers.
  • the patient improves when triggers are absent.