From the Guidelines
For persistent neuralgia after varicella zoster virus (VZV) rash resolution, acyclovir is generally not recommended. Instead, treatment should focus on managing postherpetic neuralgia (PHN) with medications specifically targeting neuropathic pain. First-line treatments include:
- Tricyclic antidepressants (such as amitriptyline 10-25mg at bedtime, gradually increased to 75-150mg as tolerated)
- Anticonvulsants (gabapentin starting at 300mg daily and titrating up to 1800-3600mg daily in divided doses, or pregabalin 150-600mg daily in divided doses)
- Topical lidocaine 5% patches applied to the affected area for 12 hours daily. Acyclovir and other antiviral medications are most effective when started within 72 hours of rash onset to reduce viral replication and may help limit the severity and duration of acute herpes zoster, but they have not been shown to effectively treat established PHN, as supported by 1. This is because PHN results from nerve damage that has already occurred during the acute infection, rather than ongoing viral activity. Pain management should be tailored to the individual patient, considering factors such as age, comorbidities, and potential drug interactions, and should follow guidelines for neuropathic pain, as outlined in 1.
From the Research
Treatment of Postherpetic Neuralgia
- The treatment of postherpetic neuralgia (PHN) typically involves a hierarchical approach, with calcium channel α2-δ ligands (gabapentin and pregabalin), tricyclic antidepressants (amitriptyline, nortriptyline, or desipramine), or topical lidocaine patches as first-line drugs 2.
- Other pharmacological treatment options for PHN include alpha-2 delta ligands, other anticonvulsants, tricyclic antidepressants, topical analgesics, tramadol, or other opioids 3.
- Gabapentin has been shown to be effective in reducing pain and improving sleep in patients with PHN, with a recommended dosage of 300 mg at bedtime on day 1,300 mg BID on day 2, and 300 mg TID on day 3, titrating up as needed to 2400 to 3600 mg/d 4.
Use of Acyclovir in Postherpetic Neuralgia
- There is no direct evidence to support the use of acyclovir in the treatment of PHN once the rash has disappeared 2, 3, 5.
- Antiviral therapy, including acyclovir, is effective in treating acute varicella and herpes zoster, but its role in preventing PHN is unclear 5.
- Initiating treatment with gabapentin and antiviral concomitantly as soon as the rash develops may reduce the severity of complications, but there is a lack of data showing these medications preventing the development of PHN 5.
Diagnosis and Treatment of Herpetic Visceral Neuralgia
- Herpetic visceral neuralgia without rash can be easily misdiagnosed due to the absence of a rash or herpes, resulting in delayed treatment 6.
- The treatment for herpes zoster neuralgia or postherpetic neuralgia can be applied to patients with herpetic visceral neuralgia without rash, and the therapeutic effects can be satisfactory 6.