Effectiveness of antiviral treatment on acute phase of herpes zoster and development of post herpetic neuralgia: review of international publications.

Herpes zoster is due to the reactivation of the virus causing varicella, called varicella-zoster virus. It affects peripheral nerves and causes painful skin and nerve lesions. This pain may last for months, or years after the initial lesions have resolved: post-herpetic neuralgia is the most frequent complication. Antiviral drugs, acting directly on the infectious agent are prescribed to reduce or block viral replication, relieve pain, and shorten symptom duration, especially for people of 50 years of age or more. However, there is currently no systematic collection of data concerning the effectiveness of antiviral drugs administered outside of clinical trials. This review evaluates the effectiveness of antiviral drugs on: (a) the intensity of pain and progression of the rash during the acute phase of herpes zoster, and (b) the frequency, intensity, and duration of post-herpetic neuralgia. During the acute phase, antiviral drugs (acyclovir, valacyclovir and famcyclovir) significantly reduce the intensity of acute pain, accelerate the healing of the vesicular rash, and reduce the duration of viral excretion. According to some authors, these drugs taken at an early stage of the disease would help to prevent the development of post herpetic neuralgia. But for others, there is no convincing evidence that antiviral drugs reduce the risk of painful complications.