What painkillers are helpful for trigeminal neuralgia?

Several: The common medications used are: neurontin, (gabapentin) trileptal, Dilantin and tegretol. These are not "painkillers" but rather work on the nerve conduction to alleviate the pain of trigeminal neuralgia.

Carbamazepine : Usually the fist choice is carbamazepine. Other antiepileptics may be useful as well as baclofen.

Anticonvulsant drug: Carbamazepine was found to be effective for trigeminal neuralgia and has been the most prescribed medication for management this disorder. A relatively new anticonvulsant, Neurontin, (gabapentin) is now considered a first line drug for trigeminal neuralgia along with carbamazepine.