I have seen improvements in my pain with DM also.

I used a generic tablet of guaifenesin and DM (WalMart's Mucus Relief) last spring for a bronchitis/cold I had. (I cannot take decongestants because of my blood pressure). I estimated I was using 80mg/24 period for at least 10 days for my severe coughing. This helps me prevent pneumonia. You can buy DM alone without guaifenesin...it is called Delsym, but it is more expensive than using the WalMart tablet I used. Mucinex DM is the same too, but also quite expensive. 40 tablets of the WalMart product are $7.95. DM is highly abusable and teenagers frequently buy it. Costco and SAMs stopped selling their generic cough syrup because of this. But WalMart still has the affordable tablets. You might have trouble finding enough DM to buy and you may be asked to show your driver's license depending on what state you live in. Really high doses of DM as used by abusing kids, causes mental dissociation, which they consider a "high". (Coricidin HBP is also a favorite of theirs).

My PN in my feet was improved dramatically.
So sometimes I take a slug(15ml) of the cough syrup at night. I have sinus drainage too, which it helps. One of our PN members went to a trial/study of DM for chronic pain, but it didn't work for him. I have seen studies over the years...one that used DM after surgery, to reduce the doses of Morphine needed.

So yes, if you have some pain relief, this is a viable option.
Here is my thread from that time last Spring:
http://neurotalk.psychcentral.com/sh...xtromethorphan
Only warning I have is if you take Cymbalta or other antidepressants of the serotonin reuptake type, you shouldn't use DM because of the risk of serotonin syndrome.

DM is the dextro isomer of levorphanol, a very potent narcotic analgesic.