I took 2 mucinex DM rather than 1 as directed by mistake. Should I be concerned? What can I expect?

I looked it up and it says to not take two doses at once. I feel certain you will be fine but if you are still concerned contact this number 1 800 222 1222. It is the national poison control hot line. They will be happy to help you. You can also call your pharmacist. Drink plenty of water and expect to be dry mouthed. Hope this helps!!