It doesn't hurt but it's not made to last long periods of time... When it's used around the corners of your mouth it's not ideal to eat or drink or any of that either... If it's in the budget, I'd go with prosthetics... PM if you need some.
Not raggin' on collodian though, it's got it's uses and I've seen people do wonderful things with it. Id suggest stippling some adhesive on before it, do several layers to get the desired effect then stipple another layer of adhesive (preferably prosaide) or MAYBE a thin layer of latex... SOMETHING to seal it and make it last a LITTLE bit longer...