For genital herpes primary and mucosal herpes simplex of the skin in immunodeficient individuals, the usual dosage for adults is 0.2g/dose, 5 times/day for 5 days or 0.4g/dose, 3 times/day for 5 days. Recurrent infections 0.2g/dose 5 times/day for 5 days. Chronic suppressive therapy for recurrent infections 0.2g/dose 3 times/day for 6 months, dose may be increased to 5 times/day at 0.2g/dose for 6-12 months if necessary. The usual dose for adults with herpes zoster is 0.8g/dose, 5 times/day for 7-10 days. Dose should be adjusted for adult patients with renal insufficiency, or as directed by the physician. For children over two years old with varicella, 20mg/(Kg.times) by weight, 4 times/day for 5 days, and start treatment immediately when symptoms appear. for children over 40Kg, the usual adult dose is 0.8g/time, 4 times/day for 5 times.