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How to Use Valtrex After a Cold Sore Has Erupted

Valtrex is a prescription antiviral medication that works by slowing down the progression of the herpes virus, allowing the body to heal from outbreaks, such as cold sores. Valtrex is available in 500 mg and 1 g tablets. The typical adult dosage for cold sore treatment is 2 g every 12 hours for one day, but your doctor may adjust your dosage to accommodate your specific needs. Valtrex therapy may be started after a cold sore has erupted, but the best treatment results are achieved by beginning Valtrex therapy at the first signs of a cold sore, such as tingling, burning or blisters.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.

Read all prescription information provided with your Valtrex prescription before beginning Valtrex therapy. Discuss any questions or concerns with your doctor or pharmacist. For best results, Valtrex therapy should be started as soon as possible after the first signs of a cold sore appear.

Long-Term Side Effects of Valtrex

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Take two 1 g Valtrex tablets with a full glass of water. To ensure proper kidney function, drink plenty of water throughout the course of Valtrex therapy. Valtrex may be taken with or without food, according to 1.

Swallow two 1 g Valtrex tablets 12 hours after first dosage, or as directed by your doctor.

Vaseline Lip Therapy on a Cold Sore

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Continue taking Valtrex as directed for the length of time prescribed by your doctor. Keep in mind that cold sores remain contagious for several days after the lesion has healed.


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. To avoid spreading the virus to others, avoid kissing and sharing items that have come into contact with your mouth and wash your hands frequently until cold sore lesion has completely healed.


Side effects of Valtrex include headache, dizziness, drowsiness, nausea, vomiting, diarrhea, constipation or allergic reaction. Make sure your doctor and pharmacist are aware of all medications and supplements you are taking, as well as your medication allergies. Alert your doctor if you are pregnant, nursing or planning to conceive.