The patient was a 77-year-old man with chief complaints of left lower jaw pain and discomfort. He had pain centering on the left lower jaw and was diagnosed with trigeminal neuralgia involving the third branch of the trigeminal nerve by a local physician. The pain subsided temporarily by administering carbamazepine, but recurred in the same region. He was subsequently referred to our ambulatory pain clinic. Sudden bouts of pain occurring dozens of times a day were noted, with depression, anorexia, lack of motivation, dry mouth, cold extremities, and dry skin. A crimson colored and slightly enlarged tongue with teeth marks on the border, crimson color on the tip, and white moss, were noted in the tongue examination. Pulse examination revealed a sunken pulse and abdominal examination noted epigastric discomfort and weakness (2/5) of the lower abdominal region. Mandibular nerve block temporarily resolved the pain, but there were repeated cycles of exacerbations, between which the feeling of discomfort persisted. Yokukansan extract (7.5 g divided into 3 doses per day) was administered, 35 months after the first clinic visit to address the discomfort that persisted after resolution of pain. Discomfort resolved. Currently, the patient still does not require mandibular nerve block or analgesics. Here we report this case in which Yokukansan was effective against discomfort in trigeminal neuralgia.