Be aware that a lot of medications, especially anti-depressants and neurological drugs, can have serious side-effects. I have fibromyalgia, which causes severe chronic pain. One theory is that it might be something of a miscommunication between the nerves and the brain, with the nerves sending off "pain" signals where none exists. Basically, the pain is real, but there's no logical explanation for it. In any case, I've tried a whole host of medications to try and control the pain, including anti-seizure drugs, anti-depressants, and drugs that work by calming the nerve-endings, as well as narcotic painkillers.
Lyrica is a nerve-ending calmer, and it worked pretty well, but it caused me to gain 40 pounds, and when I became at risk for diabetes, I had to stop taking it. I gained all that weight because the drug made me crave sour candy. We aren't talking, "Oh, that sounds yummy," but more like, "Oh, God, give me candy now. Right now, or I'll die!"
One of anti-seizure drugs scrambled my brain. I started stuttering, and mixing the syllables of my words, so something like, "popcorn," might come out, "porkcon" or "cornpop." I also had trouble comprehending what others were saying. I could understand their words, but what they were saying didn't make sense. It was like there was some kind of barrier, preventing me from truly understanding what people were saying. Sorry, I know that's vague, but it's really hard to explain. I kept getting in trouble with my parents because they would tell me to do something, and I wouldn't understand what they meant, so I wouldn't do it. And if I questioned my father, he assumed I was being defiant, belligerent, or disrespectful, so I'd get in trouble for that. It was a really rough time, until I finally figured out it was the medication causing the problem. Took awhile for the effects to wear off--I kept stuttering for the next year or so.
Anti-depressants cause really bizarre side-effects for me. One tightened the muscles in my neck and jaw, so I kept convulsively swallowing. It was a one-in-a-million side-effect, my doctor said. She actually wanted to write a paper about it for a medical journal. Weight gain is very common, as are sexual side-effects (reduced or increased desire--usually decreased).
Pain meds mostly just make me sleepy. I've never had a "high" from any of them, they'll reduce the pain, but not enough to make me feel good. Just tolerable. Vicodin makes me feel edgy. I don't know how to describe it better than that, but I feel kind of raw and on edge, like there's a constant hum or vibration that's getting on my nerves.
They might send him to a pain rehabilitation clinic, if he's suffering a great deal from chronic pain. They teach you how to breathe properly, how to relax, how to exercise, how to stand, and pick things up properly, stuff like that. Some of it's helpful, but a lot of it was totally worthless. Like doing twenty sit-ups a day is going to make my pain go away? Really?
If you want more, you can PM me.