What is postherpetic neuralgia (PHN)? Postherpetic neuralgia, also known as post-herpetic neuralgia, is a persistent neuralgia that remains after the healing of herpes zoster lesions and can last for months, years, or even more than 10 years, and is basically ineffective when treated with oral analgesics, making it a difficult and persistent pain in clinical treatment. It is called “malignant pain caused by benign disease”. What is the mechanism of PHN? Herpes zoster is a respiratory transmitted viral infection, which is a neurophilic varicella-herpes virus. After infection into the bloodstream, it is latent in the sensory ganglia (cerebral ganglia or dorsal root ganglia of spinal nerves). In addition to the local skin, the sensory nerves are also damaged. The damaged nerves are susceptible to ectopic discharge, cross-talk and central sensitization due to demyelination and scar formation, resulting in intractable neuralgia. What are the clinical features of PHN? Herpes zoster is a respiratory-transmitted infection that can occur in all ages from children to the elderly, but leaves sequelae of PHN in only 9% to 13% of cases, and in patients with herpes zoster over 50 years of age, the incidence of PHN can be over 50%. PHN is typical of neurogenic pain and often manifests as spontaneous pain and abnormal sensory pain. The spontaneous pain is random and persistent pins and needles, knife-like, burning, electric shock-like pain or flashing or throbbing pain; abnormal sensory pain is manifested as nociceptive hypersensitivity or hypersensitivity: the skin of the affected area feels painful when it is slightly rubbed by clothing. the pain of PHN is often heavy at night, and patients often cannot sleep at night and are in pain. Can PHN be cured? Herpes zoster is self-healing and the lesions (blisters) will heal on their own within 2 to 3 weeks without treatment, so the people are convinced that a “miracle doctor” can “kill the snake” by applying a circle of ink, drawing a charm, reciting a few incantations, and gesturing with a knife. In fact, it is because herpes heals naturally. Some people think that since it can heal itself, there is no need to treat it. In fact, it is the skin lesions that heal on their own, but the sequelae of neuralgia not only do not heal on their own, but are also very difficult to treat.