Your physical therapist was partly correct and partly wrong. Yes narcotic painkillers (and other medications as well) can cause something called 'rebound' in which after a period of time the very symptoms the medication is supposed to treat (and did treat for a time) come back even stronger. The rebound effect with pain medication is well known in people with migraines. Interestingly most of the information on rebound refers to headaches and not other types of pain.
Your PT erred in stating that hydrocodone 'will' cause this effect. Rebound only occurs in a small percentage of patients and many patients are able to take these medications for years without having this problem.
I'm so glad you ask this question. I hope someone answers. I have been taking tylenol #4 for about a year. It seems at times this medication makes the pain worse. I ask my doctor if this is possible, he just looked at me like I was crazy and said, NO. I don't think he really cares anyway. Last week when I went to see him he was running us in every 15mins. like clock work. I said, "your fast today", he said, "ya, as long as people don't have to talk".
I used to have a doctor like that. the last time I went to him he didn't even look at me. I now have a lovely woman doctor who actually looks me in the eye and talks to me. We worked out a plan for my health together.
I found this to be true. Maby I took to much. I took one pill every 4 hours but as the 4hr mark approached my pain was much worse.