The dosage of the drug is given differently to certain viruses. A 5-day course of the drug is enough for the treatment of herpes. For 5 days, the dosage will 200mg pills 5 times a day. If the virus is still not dead, the treatment will be extended. For other diseases like HIV and chickenpox, the dosage should be 800mg 5 times a day. The duration of the drug should be decided by the drug for the best results.