Which medications in the drug class Antivirals are used in the treatment of Herpes Zoster?

Updated: Feb 11, 2021
  • Author: Camila K Janniger, MD; Chief Editor: Dirk M Elston, MD  more...
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Antiviral agents exert a direct antiviral effect on varicella-zoster virus (VZV). Nucleoside analogues initially are phosphorylated by viral thymidine kinase, eventually forming a nucleoside triphosphate. These molecules inhibit herpes simplex virus (HSV) polymerase with 30-50 times the potency of human alpha-DNA polymerase.

The goals of antiviral therapy are to decrease pain, to inhibit viral replication and shedding, to promote healing of skin lesions, and to prevent or reduce the severity of postherpetic neuralgia. Antiviral therapy may decrease the length of time for new vesicle formation, the number of days to attain complete crusting, and the days of acute discomfort. Initiate treatment as soon as possible because treatment is most effective within 72 hours of eruption.

Acyclovir (Zovirax)

Acyclovir is a synthetic purine nucleoside analogue with in vitro and in vivo inhibitory activity against human herpes viruses, including HSV type 1 (HSV-1), HSV-2, VZV, Epstein-Barr virus (EBV), and cytomegalovirus (CMV). In cell cultures, acyclovir has the highest antiviral activity against HSV-1, followed, in decreasing order of potency, by HSV-2, VZV, EBV, and CMV.

Treatment with acyclovir is indicated in patients with involvement of the first branch of the trigeminal nerve, those who are immunocompromised, or those with increased risk for major complications from a varicella infection (ie, patients older than 13 years, those receiving long-term corticosteroid or aspirin therapy, and those with chronic cutaneous or pulmonary diseases). Zoster in adolescents may be treated with oral acyclovir if it is initiated within 72 hours of eruption.


Famciclovir is a prodrug that, once ingested, is rapidly biotransformed into the active compound penciclovir and phosphorylated by viral thymidine kinase. By competition with deoxyguanosine triphosphate, penciclovir triphosphate inhibits viral polymerase. Activity against HSV-1, HSV-2, and VZV has been demonstrated.

Therapy should be initiated as soon as herpes zoster is diagnosed. No data are available on the efficacy of treatment started 72 hours after rash onset. The dosage should be adjusted in patients with renal insufficiency or hepatic disease.

Valacyclovir (Valtrex)

Valacyclovir is an L-valyl ester of acyclovir. It is rapidly converted to acyclovir, which has demonstrated antiviral activity against HSV-1, HSV-2, VZV, and other viruses.

Therapy should be initiated at the earliest sign or symptom; it is most effective when started within 48 hours of the onset of zoster rash. No data are available on the efficacy of treatment started 72 hours after rash onset.

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