Hypersensitivity

Patients with ME/CFS can have a range of hypersensitives, which may mild or severe. Hypersensitives recognized in ME/CFS include sensitivity to:


 * light (photophobia)
 * sound (hyperacusis)
 * touch
 * foods intolerances
 * odor sensitivities
 * chemicals, including developing multiple chemical sensitivity (MCS)
 * vibration sensitivity

Hyperalgesia, which is a greatly increased sensitivity to pain, may also occur.

Canadian Consensus Criteria
Perceptual and sensory disturbances count as one of the Neurological/Cognitive manifestations used for diagnosis, the examples given are: "spatial instability and disorientation and inability to focus vision". Ataxia, muscle weakness and fasciculations are common. There may be overload phenomena: cognitive, sensory–e.g., photophobia and hypersensitivity to noise–and/or emotional overload, which may lead to "crash" periods and/or anxiety."1,2

The following hypersensitivity and sensory symptoms are recognized in Appendix 4:

International Consensus Criteria
Hypersensitivities are divided into a few main areas, as optimal diagnostic criteria:
 * Neurocognitive symptoms:
 * Immune, Gastro-intestinal and Genitourinary:
 * Immune, Gastro-intestinal and Genitourinary:

Allergies
Most hypersensitives are not allergies and are mediated by different antibodies, for example a peanut allergy causing anaphylactic shock is a Type I hypersensitivity mediated by the IgE antibody, and is different to a Type IV hypersensitivity such as contact dermitatis caused by poison ivy.

Only Type I hypersensitives are classed as allergies.

Antibodies
A number of different antibodies have a role in hypersensitivities, including IgG.