May give with food. Genital herpes: Initially 200mg every 4hrs (5 times daily) for 10 days. Chronic: 400mg 2 times daily or 200mg 3–5 times daily for up to 12 months, then reevaluate. Intermittent: (at 1st sign of recurrence) 200mg every 4hrs (5 times daily) for 5 days. Herpes zoster: 800mg every 4hrs (5 times daily) for 7–10 days. Varicella (start at earliest sign/symptom): 800mg 4 times daily for 5 days. Renal impairment: reduce dose (see full labeling); give another dose after hemodialysis.
<2yrs: not recommended. ≥2yrs: Varicella (start at earliest sign/symptom): 20mg/kg 4 times daily for 5 days; max 800mg/dose. >40kg: as adult. Others: see full labeling.
Renal impairment: see full labeling. Maintain adequate hydration. Pregnancy (Cat.B). Nursing mothers.
Avoid nephrotoxic drugs. Potentiated by probenecid.