have you ever seen them in the stores? the cough drops with the vitamin c in them? apparently they make wonderful treats. my new puppy just managed to somehow get them from the dining room table and eat the whole pack before i knew it!
oh my! my dog LOVES coughdrops i always forget i have them in my backpack or i leave them in the pockets of my jeans and i find him freaking out pawing at either or, i used to ALWAYS keep cherry ricola in the cellphone holder of my hiking pack and he would take the entire pack out and i'd find the wrappers all over the floor. They didn't have any negative effects, I'll look into the halls as treats thats a good idea but too much vitamin C can ruin teeth, it calcifies and starts eating away at the enamel. Just fyi.
I did some research online because Lilo decided to check out a roll of Halls that my brother left out. From what I've read, the only reported major side effect is explosive (yes, explosive) diarrhea and possibly some tummy ache. Lilo didn't experience this--but i'm convinced that she has the stomach of a goat.
Of course, anything in excess can be potentially dangerous.