Written informed consent will be obtained from all the study participants. Patients who satisfy the eligibility criteria will be enrolled in the study and their pain will be assessed using 10 point (100 mm) visual analog scale (VAS). Following this they will be randomized in the ratio of 1:1 to receive either famciclovir 500mg 3 times daily or valacyclovir 1000mg 3 times daily for a period of 7 days. The drugs will be given in similar looking capsules to blind both participant and the investigator.

Participants will be given adherence sheet as well as pain rating sheet to be filled for 7 days and to be returned during 8^th day follow up visit. They will be evaluated for pain using VAS and crusting of the cutaneous lesions on day 8 by the blinded observer. The intake of analgesics if any during the study period will be recorded. Following this they will be given a sheet to note down the day of complete healing of lesions.

The lesions are defined as fully crusted when all the papules and vesicles in the affected dermatome had resolved and crusts had appeared. If all cutaneous lesions do not crust by 8^th day, the patients will be continued on the same drug for another 3 days and will be followed up on 11^th day to look for complete crusting of lesions. The participants will be followed over telephone at the end of four weeks and 12 weeks to find out the time taken for healing of cutaneous lesions as well as complete disappearance of pain. Healing is defined as the first time in which a patient had no papules, vesicles / crusts and after which did not develop them at any later visit.