If carbamazepine isn't working to treat my trigeminal neuralgia, what is a good drug to try next?

Trileptal. is reported to be effective for trigeminal neuralgia. Some clinicians now prefer to use oxcarbazepine (Trileptal) as their first line drug for trigeminal neuralgia because of its reduced side effect profile. Unfortunately, about half of TN sufferers eventually become dissatisfied with medical therapy, explore surgical options.
Several. Drugs with best success rates: Carbamazepine and oxcarbazepine. Next level: gabapentin, pregabalin. Another effective drug: baclofen. Further down the line: lacosamide, topiramate, lamotrigine, levetiracetam. Some add on treatments: topical or nasal lidocaine. The list goes on... Sometimes it isn't that the drug doesn't work, but it may not be used in the best manner.
Varies. Carbamazepine used to be the main agent in treatment of trigeminal neuralgia years ago. We now have a multitude of anti-neuropathic agents with better side effect profile. To list a few, we have lyrica, (pregabalin) neurontin, topamax, etc. The choice is based on coexisting medical issues and other medications on which patient is placed. The physician can make this determination on a case by case basis.