Efficacy of Yokukansan, a traditional Japanese herbal medicine, in patients with dizziness and irritability

Objective Irritability is an emotional stress symptom that causes or exacerbates dizziness. Antidepressants may be helpful for some conditions that are accompanied by irritability; however, they do not completely inhibit irritability. Yokukansan (YKS), a traditional Japanese herbal medicine, has been used for neurosis, insomnia, and children's irritability and night crying. The study investigated the efficacy of YKS in nystagmus in patients with chronic dizziness and irritability. Methods Twenty-two cases with chronic dizziness and irritability were reviewed retrospectively. The patients were divided into two groups: control patients (0–7 days of treatment) and YKS-treated patients (YKS cases; >7 days of treatment). Dizziness before and during (after, in the controls) YKS treatment was evaluated by scoring the nystagmus intensity on a 5-point scale. The average scores were calculated within a maximum of 6 months before and during or after treatment. The normalized scores were also calculated. The optimal treatment regimen was calculated via receiver operating characteristic (ROC) curve analysis. Results There were six control cases (1 male, 5 females; mean age: 59.5 years). There were 16 YKS cases (3 males, 13 females; mean age: 61.8 years). While the group mean nystagmus intensity scores significantly decreased from 1.18 to 0.73 in the YKS cases, it did not change in the control cases. The group mean of the normalized nystagmus intensity scores during treatment was 0.73 in the YKS cases. The results of the ROC curve analysis indicated the optimal cut-off period of the YKS treatment was 10 days. Conclusion The oral administration of YKS for more than 10 days was optimal. The treatments with YKS could be a good option for the treatments of vertigo.