Hi..yes Zovirax is antiviral which is the only and very good medicine for chicken pox..start it as early as possible and take its full course 5 times a day for 5 days. It gives very good effect if started within 48 hours of onset of lesions.  Fresh lesions will come 4 to 5 days and then scab will form which will fall in another 5 to 7 days.Take full rest and follow isolation if feasible..avoid public places. Take tab Crocin SOS in case of fever Apply calosoft lotion over the rashes