The main culprit in the cinnamon powder is actually derived from tree bark and contains cellulose, an undigestible fiber capable of producing a strong inflammatory response in lung tissue, leading to long term wheezing and a chronic cough, potentially placing patients at further risk for bouts of pneumonitis or even aspiration pneumonia.

FORBES: An ER Doctor's Perspective on "The Cinnamon Challenge": Don't Even Think of Doing It