Tip. Talk to your doctor if you experience cold sores frequently or can identify a cold sore trigger, such as exposure to intense sunlight. He may choose to prescribe Valtrex therapy as a preventive measure. Valtrex has been proven as a successful treatment for cold sores. You must take the medication as soon as you feel a cold sore coming on. Timing is everything when taking Valtrex, the sooner you take it, the better your success. Aug. 27, 2002 -- Here's good news for cold sore sufferers. Just one day of treatment with a medication called Valtrex makes the unsightly, painful sores disappear faster. Valacyclovir (Valtrex) for Cold Sores. For cold sores, valacyclovir is usually taken in two large doses of 2,000 mg, split 12 hours apart from each other. Like with other outbreaks of HSV, valacyclovir will speed up the speed at which cold sores heal, but it can still take seven to 10 days for them to fully disappear. Worried About Herpes? Act Quickly for Faster Relief. From cold sores to. This may be because you get cold sores often or if you’re at high risk of serious complications, such as from a weakened immune system. To treat a cold sore, you take Valtrex on the day you. A: When you take Valtrex for cold sores the dose is 2,000 mg (2 grams) as soon as you feel the warning signs of a cold sore (a spot on your lip that tingles, itches or burns) and another 2,000 mg 12 hours later. Valtrex is used to treat cold sores in children who are at least 12 years old, or chickenpox in children who are at least 2 years old. Valtrex will not cure herpes and will not prevent you from spreading the virus to other people. No, you should not exceed the recommended dosage of 2 grams twice daily for 1 day taken 12 hours apart. Therapy should be initiated at the earliest symptom of a cold sore (e.g., tingling, itching, or burning). In this article, I’m going to teach you how to use Valtrex for cold sores. Ninety percent of all people get at least one cold sore in their life. 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.