Cinnamon oils must never be consumed by a person, as they can be very dangerous to the human body. Cinnamon will also lead to an increased heart rate, and dyspnea (which is a kind of respiratory disorder). Women who are either pregnant, or breastfeeding, must mandatorily stay away from cinnamon and items containing cinnamon. Overuse of cinnamon can also lead to gingivitis (inflammation of the gums) and perioral dermatitis (a skin rash that occurs near the mouth). Too much of cinnamon also causes drowsiness and clammy hands or excessive perspiration on the palms. Stomach irritation can also be listed as one of the side effects of cinnamon, as too much intake causes it to affect the stomach lining. Cinnamon is also bad for people on antibiotics and blood sugar medication.
Not sure why your asking this but I know that people have died from doing something called the cinnamon challenge, which I did(I didn't know that people have died from it when I did it) and totally regretted it with in 5 seconds of putting the cinnamon in my mouth. If your trying to do the cinnamon challenge or something I would highly suggest not to. When you cough, some of it goes into your lungs and can trigger an asthma attack. Also it can seriously hurt your nose. I would know!