the.com/irritant
The small thing that wouldn't matter, except now it's all you can feel.
means Something that provokes annoyance, inflammation, or unease — chemically, physically, or in the form of your coworker.
from From Latin irritare, to excite or provoke, the same root that gave us irritate and the urge to leave the room.
ChemistryIrritants inflame tissue without permanently destroying it.
Pearl makerAn oyster's irritant becomes its only valuable product.
Legal labelWarns of harm milder than corrosive or toxic.