I ve never had a patient have any side effects from Troches other than the taste out of dozens. Local irritation from the troches should be possible. frankly I am surprised I do not see MORE of. It can certainly cause allergic reactions, but it can also directly cause plain irritation. The interactions between the narcotic and mycelex are unlikely to be much and would peak by 3 days of use together due to THEORETICAL effects of the mycelex on the metabolism of norco. There s not much evidence significant interaction occurs though. I have patients say they get local swelling from an oral medication nearly every month. Because this can be the beginning symptom of an allergic reaction that can be fatal, I always tell them to stop using the medicine. It can be tricky to know which one is the cause!