What Multiple Chemical Sensitivity is not
MCS is not having an increased sense of smell. That’s hyperosmia.
MCS is not finding the smell of perfume or other chemicals unbearable. That’s probably the olfactory equivalent of being sensitive to noise or light.
People with MCS get symptoms when they are exposed to low levels of chemicals they are sensitive to. They may or may not be able to smell the chemicals. Some people with MCS do have an increased sense of smell, but there are also people with MCS who have no sense of smell at all. People with MCS often react to chemicals that have no odour.
Some people can’t stand strong smells, or in some cases any smells at all. This doesn’t mean they have MCS. Some people with MCS find some smells unbearable, but people with MCS can also like the smells of chemicals they react to or not even notice them.
Some people with MCS feel anxious about chemicals they react to, but others don’t. People with MCS are probably more likely to be anxious about chemicals than people who don’t have MCS, just as people who have been bitten by a dog are probably more likely to be anxious about dogs than people who haven’t been bitten by a dog. However, nobody would confuse the symptoms of anxiety with the symptoms of a dog bite, but it is possible to confuse the symptoms of anxiety with symptoms of MCS.