This is a multicenter, randomized, double-blind, parallel-group, active controlled comparative study of the safety and efficacy of 2 dosing regimens of FV-100 versus valacyclovir administered for 7 days in subjects with uncomplicated AHZ(acute herpes zoster).

This is a multicenter, randomized, double-blind, parallel-group, active controlled comparative study of the safety and efficacy of 2 dosing regimens of FV-100 versus valacyclovir administered for 7 days in subjects with uncomplicated AHZ(acute herpes zoster). Subjects diagnosed with uncomplicated AHZ within 72 hours of lesion appearance and worst pain of 4 or greater at day 1, will be randomized (1:1:1) to one of three treatment groups and will begin study treatment at the Day 1 visit(within 72 hours of AHZ lesion appearance) to either: 1. FV-100 400mg QD, 2. FV-100 400mg BID(total daily dose of 800mg), or 3. Valacyclovir 1000mg 3 times a day for a total daily dose of 3000mg. Subjects will be monitored for adverse events through day 21. Efficacy assessments for lesion status and AHZ pain are captured til day 120.

Inclusion Criteria:

• Receive a clinical diagnosis of uncomplicated AHZ as evidenced by a unilateral dermatomal rash
• Have zoster-related pain
• Are able to be randomized and receive their first dose within approximately 120 hours from appearance of rash

Exclusion Criteria:

• Have multidermal or disseminated AHZ
• Have facial, ophthalmologic or oral manifestations
• Have received Zostavax