There is no specific diagnostic test for Multiple chemical sensitivity (SQM). The symptoms are not specific and can appear in many other pathological conditions. In addition, it is common in SQM to have association with pathologies such as autoimmune thyroiditis, bronchial asthma, esophageal reflux, irritable bowel syndrome, hepatic steatosis, and various psychiatric disorders such as depression or anxiety-depressive disorder.

In the physical examination, some alterations that are not specific to SQM may also appear. Some of these findings are redness of the skin or various types of eczema, abdominal distension or increased abdominal perimeter. There may also be alterations in heart rhythm and a respiratory rate higher than normal. Complementary tests such as analytical, or image or allergy tests, do not allow diagnose multiple chemical sensitivity, but they are fundamental to rule out other diseases that may be causing the symptoms.

The SQM is a exclusion diagnosis by definition. This means that before being able to say that a patient has multiple chemical sensitivity, a study must be carried out to previously rule out another type of pathology with a specific cause or a specific treatment. Unfortunately, there are some pathologies that are underdiagnosed and that can give a similar or overlapped symptomatology with that attributed to SQM.

So, for example, some patients 90% of adult celiac patients not diagnosed they may end up taking the label of "SQM" when in fact their table is due to gluten intake. The SIBO (bacterial overgrowth of the small intestine) can also lead to multiple symptoms of various systems and devices of the body without often being thought of in this entity, little known by many doctors. Non-allergic food histaminosis (HANA) is another little recognized picture that can lead to similar symptoms

For the diagnosis, several self-administered questionnaires are used, such as the UTHS (University or Toronto Health Survey), the IEISI (Inventory of Symptoms of Idiopathic Environmental Intolerance), the EESI (Inventory of Exposure and Environmental Sensitivity), or its reduced version, the QEESI. The QEESI has been translated into Spanish and adapted to the Spanish population.

60 Minutes Australia 2017 - Allergic to Life: Multiple Chemical Sensitivity (November 2019).