In the first cohort, patients with stable herpes simplex virus receive valacyclovir hydrochloride at 1 of 2 doses, depending on body surface area (BSA), for 10 days. If acceptable safety is seen at this dose level, a second cohort of patients with stable herpes simplex virus receive a higher dose, depending on BSA, for 10 days. A third cohort of patients with varicella or zoster receive a selected dose based on results from the previous cohorts.