Herpes zoster is a condition of blisters, redness and pain in the corresponding skin area. Herpes zoster usually heals after about 4 weeks, however, some people still feel pain in the healed skin area, the pain lasts for more than 3 months. At that time, the patient is diagnosed with post-herpetic neuralgia. Although post-herpetic neuralgia does not directly threaten the patient's life, it makes the patient uncomfortable, directly affecting work and life.