Genetic
It has been hypothesized that there is a heritable genetic trait which pre-disposes people to be hypersensitive to low-level chemical exposure and so develop MCS. To investigate, researchers compared the genetic makeup of people with MCS, to people without. The results were generally inconclusive and contradictory, thus failing to support the hypothesis.Gaétan Carrier and colleagues write that the genetic hypothesis appears implausible when the evidence around it is judged by the Bradford Hill criteria. Psychological
Several mechanisms for a psychological etiology of the condition have been proposed, including theories based on misdiagnoses of an underlying mental illness, stress, or classical conditioning. Many people with MCS also meet the criteria for major depressive disorder or anxiety disorder. Other proposed explanations include somatic symptom disorder, panic disorder, migraine, chronic fatigue syndrome, or fibromyalgia and brain fog. Through behavioral conditioning, it has been proposed that people with MCS may develop real, but unintentionally psychologically produced, symptoms, such as anticipatory nausea, when they encounter certain odors or other perceived triggers. It has also been proposed in one study that individuals may have a tendency to "catastrophically misinterpret benign physical symptoms"  or simply have a disturbingly acute sense of smell. The personality trait absorption, in which individuals are predisposed to becoming deeply immersed in sensory experiences, may be stronger in individuals reporting symptoms of MCS.
Delsym is an American brand of cough medicine owned by Reckitt, and manufactured at Unither Manufacturing in Rochester, NY. It is different from most brands of cough medicine in that the active ingredient is "time released". The time release feature allows the drug to suppress the cough reflex for a longer period of time. The active ingredient per teaspoon (5 mL) is dextromethorphan polistirex, equivalent to dextromethorphan HBr 30 mg. Method of action
The active ingredient, dextromethorphan (metabolized to dextrorphan), is surrounded by an edible plastic called polistirex. When the Delsym arrives in the stomach, an initial amount of dextromethorphan is immediately released into the bloodstream while the rest is surrounded by a plastic that is slowly dissolved by stomach acid. After the polistirex is dissolved sufficiently, more dextromethorphan is released. Recreational use
Intentionally consuming more than the recommended dosage of Delsym may result in euphoria, lack of coordination, hallucinations, apathy, feelings of dissociation, and disorientation. This is due to dextromethorphan as well as its pharmacologically-active metabolite dextrorphan, both dissociative drugs that work as NMDA receptor antagonists the same way nitrous oxide (N2O), ketamine, and phencyclidine (PCP) do. Because of the abuse potential, many pharmacies and large retail chains have begun taking precautions such as restricting sales to those under age 18 and limiting the number of sales of dextromethorphan-containing products per customer. References
External links
Official website