Idiopathic environmental intolerances: results of challenge studies.

It has been postulated that psychophysiologic mechanisms may account for symptom generation in IEI. In this review, the similarity of IEI and panic disorder symptoms are noted. The results of various challenge studies, both with known panicogenic substances and self-identified triggers, are examined. Available data are consistent with the premise that IEI symptoms have a psychophysiologic basis.