Sexual Health STDs Herpes Treating Cold Sores With Valtrex and Other Prescription Drugs By Heather L. Brannon, MD Heather L. Brannon, MD Heather L. Brannon, MD, is a family practice physician in Mauldin, South Carolina. She has been in practice for over 20 years. Learn about our editorial process Updated on April 10, 2022 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. These medical reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Anita Sadaty, MD Medically reviewed by Anita Sadaty, MD Facebook LinkedIn Twitter Anita Sadaty, MD, is board-certified in obstetrics-gynecology. She is a clinical assistant professor at Hofstra Northwell School of Medicine and founder of Redefining Health Medical. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents FDA Approval Treatment Benefits The First Outbreak Topical Denavir Acyclovir Famciclovir Valtrex Several medications, including Valtrex, are available to treat cold sores. Some are used topically (on the skin) and others are used orally (by mouth), but the goal is to treat cold sores as early as possible. That's because starting a medication when prodromal symptoms such as burning, tingling, or redness begin will give a person with a cold sore the best chance of either preventing an actual blister from forming or shortening a blister's course once it does appear. Moyo Studio / Getty Images A Word on FDA Approval A number of antiviral medications are used to treat herpes infections, which cause cold sores, also known as fever blisters. While the FDA has approved the use of certain drugs for cold sores, some antiviral drugs aren't specifically FDA-approved for cold sores but have been shown in clinical studies to be effective treatments. Given this, receiving a prescription for an off-label use of one of these drugs may help eliminate or prevent cold sores. The decision to use a medication that is prescribed off-label should be made based on current scientific data and discussed thoroughly with your healthcare provider. Treatment Benefits Antiviral drugs can have several effects on oral herpes simplex viral infections, including cold sores. These medications can decrease the time that it takes for cold sores to heal and reduce symptoms, especially pain. If taken soon enough, treatments can prevent lesions from occurring, reduce the number and size of lesions that develop, as well as decrease the amount of viral shedding (the point at which the virus is contagious). The First Outbreak The first outbreak of any herpes simplex infection is usually worse than recurrent infections. An initial outbreak of oral herpes should be treated with oral medications, while recurrences can be treated with topical or oral medications. The first episode (which generally occurs in childhood) is also treated longer, usually for seven to 10 days with an antiviral medication. Recurrent infections, on the other hand, are treated for a shorter period of time. Topical Denavir for Cold Sores Denavir (Penciclovir 1 percent cream) is FDA-approved for recurrent cold sores. Starting treatment within one hour of an outbreak can reduce healing time by two days, as well as reduce symptoms. Denavir can also decrease the duration of viral shedding. Overall, the earlier Denavir is started, the better the benefits. That being said, improvement is often still possible when treatment is started after vesicles (the cold sores) develop. Acyclovir Zovirax (Acyclovir 5 percent cream) is also FDA-approved for the treatment of recurrent cold sores. In studies, frequent application of the cream reduced healing time by about 12 hours. Oral acyclovir given five times a day for primary gingivostomatitis in children can substantially reduce the duration of fever, eating problems, and drinking difficulties, as well as viral shedding. Using low-dose oral acyclovir for cold sores can shorten the duration of symptoms, but higher doses may be needed to reduce pain. Famciclovir Famvir (Famciclovir) is approved by the FDA for the treatment of cold sores. If started at the first sign of symptoms, taking a single high dose of Famvir can shorten the herpes infection by two days. Valtrex Valtrex (Valacyclovir) is also approved by the FDA to treat cold sores and it's a well-known, popular treatment. If started at the first sign of symptoms, taking Valtrex twice a day for one day can shorten the duration of a herpes infection. 5 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Chi CC, Wang SH, Delamere FM, Wojnarowska F, Peters MC, Kanjirath PP. Interventions for prevention of herpes simplex labialis (cold sores on the lips). Cochrane Database Syst Rev. 2015;(8):CD010095. doi:10.1002/14651858.CD010095.pub2 Chen F, Xu H, Liu J, et al. Efficacy and safety of nucleoside antiviral drugs for treatment of recurrent herpes labialis: a systematic review and meta-analysis. J Oral Pathol Med. 2017;46(8):561-568. doi:10.1111/jop.12534 Harvard Health Organization. Cold Sores. Klysik K, Pietraszek A, Karewicz A, Nowakowska M. Acyclovir in the Treatment of Herpes Viruses - a Review. Curr Med Chem. 2018. doi:10.2174/0929867325666180309105519 Vere hodge RA, Field HJ. Antiviral agents for herpes simplex virus. Adv Pharmacol. 2013;67:1-38. doi:10.1016/B978-0-12-405880-4.00001-9 Additional Reading Centers for Disease Control and Prevention. (2015). Sexually Transmitted Diseases Treatment Guidelines. Usatine RP, Tinitigan R. Nongenital Herpes Simplex Virus. Am Fam Physician. 2010 Nov 1;82(9):1075-82. By Heather L. Brannon, MD Heather L. Brannon, MD, is a family practice physician in Mauldin, South Carolina. She has been in practice for over 20 years. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit