The Analgesic Efficacy and Safety of Venlafaxine for Prevention of Postherpetic Neuralgia in Patients With Acute Herpes Zoster

Inclusion Criteria: * 1\. Ages more than 18 years; * 2\. Patients with onset of HZ rash less than 30 days; * 3\. Experiencing moderate to severe HZ pain with an average pain score of at least 4 on a Numeric Rating Scale (NRS, 0 = no pain, 10 = worst possible pain); * 4\. Aspartate aminotransferase and alanine aminotransferase levels less than twice the upper limit of normal; * 5\. Estimated glomerular filtration rate of 30 mL/min per 1.73 m2 or higher; * 6\. Willing to sign the informed consent form and possessing sufficient cognitive and language abilities to comply with all the study requirements. Exclusion Criteria: * 1\. HZ with head, neck, ocular, mucous membrane, cranial nerve, or central nervous system involvement or generalized HZ; * 2.Known hypersensitivity to venlafaxine; * 3.History of major depressive disorder requiring antidepressant therapy; * 4.History of systemic immune diseases, organ transplantation, or cancers; * 5.Pregnancy or lactation; * 6.Presence of acute or chronic pain disorders other than HZ.