Carry it on! Never put something that important in your checked luggage!
You will most likely have to pull it out of your bag and they will hand check it and pass it through the scanner. They may swab it just to be sure it is legit, but they see them everyday.
I keep all my medical stuff in one backpack-- nebulizer, meds in a ziplock bag, my foot brace and anything else I need. I keep the neb and the meds arranged so it is very easy to pull them out and put them back in. It is no problem for security, but do be sure to allow yourself extra time for the extra checks they will do.