What happens if you eat too much cinnamon?

There is more than one kind of cinnamon, but consuming more than 1 gram per day of the most common type of cinnamon in the supermarket will result in coumarin poisoning. Consuming too much of anything will kill you, including cinnamon, nutmeg, and even water. Have as much cinnamon on your toast as you like, but don't ever eat something like cinnamon by the handful.