**4. Conclusion**

Neither obvious pathogenesis nor an established treatment have been clarified or established for PHN. Our study indicated that advanced age and deep pain at the first visit were shown to be predictive factors for PHN. DM and pain reduced by bathing should also be considered as potential predictors of PHN. We further reviewed recent pharmacotherapeutic results for PHN. To improve patient safety and the likelihood of achieving satisfactory outcomes, prospective studies are needed to establish optimal treatments including pharmacotherapy for PHN.
