I spent several days over the last week not feeling well with a possible stomach bug. As a result, I took Tums several times- having taken them many times before without ever having an issue, it didn't occur to me at first to peel the label back to check the ingredients. However, when I did, I noticed they cleary state "contains: gluten (wheat)" No wonder I wasn't feeling any better! From the ingredients, it isn't clear where the wheat comes from... but just the same, I won't be using those again.
The Tums in question were Smooth Dissolve, fruit flavored.