sighanide

A toxic chemical that was sneakily added to OTC medications like Tylenol™ in the early '80's; its typical effect was to cause the meds’ consumers to frequently heave deep fretful inhalations and otherwise behave in a restless dissatisfied manner.

OTC meds are now “sealed for your protection”, but that doesn’t seem to stop some grumpy cantankerous individuals from exhibiting sighanide-like symptoms, anyway.