 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  How to use Valtrex Read the Patient Information Leaflet if available from your pharmacist before you start taking valacyclovir and each time you get a refill. If you have any questions, ask your doctor or pharmacist. Take valacyclovir by mouth, with or without food, as directed by your doctor. Drink plenty of fluids while taking this medication to lower the chance of side effects. The dosage and length of treatment are based on your type of infection, medical condition, and response to treatment. For treating chickenpox in children, the dosage is also based on weight. This medication works best when started at the first sign of an outbreak, as directed by your doctor. It may not work as well if you delay treatment. For shingles or chickenpox, start taking valacyclovir at the first symptom or as soon as possible after the rash appears. For cold sores or genital herpes, start taking this medication at the first sign or as soon as you feel tingling, itching, or burning. Valacyclovir works best when the amount of medicine in your body is kept at a constant level. Take this drug at evenly spaced intervals. To help you remember, take it at the same time(s) </s>