Generally, narcotics are not accepted as an effective source of pain relief for nerve pain (which, of course, TN is).
http://www.howtocopewithpain.org/blog/169/medication-pain-narcotic-opiate/
1. Effectiveness
Unfortunately, while narcotics are great for acute pain, they often don’t work so well for chronic pain, especially nerve pain. The balance of good effects versus problems may not be so favorable in chronic pain.
Some people report relief with the morphine suckers, but to honest, I'm not going there.
Are you taking any of the meds generally recommended for TN pain relief-Tegretol, Neurontin, Lyrica, Dilantin, Baclofen, Gabitril, Klonopin, etc? If you are, I've found that it sometimes takes a "cocktail" mixture of these to be effective. At one point, I was on 4 or 5 at one time.
If you have exhausted all of the pharmacological avenues without relief, it may be time to research surgical relief.
I had a Gamma Knife (which really is not surgical, as it is non-invasive)12 yrs ago, after I had gone the route of medications. For about 9 yrs, I was totally pain free. Now I have minimal-moderate pain, but get relief with 1200mg of Tegretol daily.
If you have any questions, please feel free to PM me.
Good luck.