 [ Symptoms ] herpes cold sore or angular chelitis  this thing appeared on the side of my lip that looks like a blister but is split in the middle on either side of the split there is excess skin and it hurts when i open my mouth when it was closer to healing there seemed to be a yellow crust around it i have never had a herpes cold sore before so it is going to break my heart if i have just gotten the virus it is taken about 2 weeks to heal probably because i messed with it in the beginning never noticed and small blisters though [ Disease ] you are wise to ask this question whenever someone is taking a pain reliever especially a narcotic it is good to consider whether or not an over the counter medication may interact with it i can not tell if you are referring to oxycodone or oxycontin but either way unisom should not interact with it the main ingredient in unisom that makes you sleep is a big whopping antihistamine it is not benadryl diphenhydramine but a relative of that however different over the counter sleep aids may contain a different active ingredient from unisom your best bet is to ask the pharmacist which sleep aid you can safely take with your pain reliever wishing you well