I am 5 weeks pregnant and have taken benadryl elixir to help me sleep. I see now that it has cinnamon in it. Will this cause a miscarriage?

No. Cinnamon will not cause miscarriage. For the sake of your and your baby's health, you should be under the care of an obstetrician. If you have not seen one, please see one at your earliest. Wish you good health and a healthy baby!