Cold sores, also known as herpes labialis, are small sores around the lips and mouth that are often caused by a virus known as herpes simplex virus 1, or HSV-1. These sores, especially when they appear for the first time, may be painful and last from one to two weeks. Online medical reference UpToDate contributor Kimon Zachary reports that recurrent outbreaks of cold sores affect about 1/3 of the population in the United States. Fortunately, there are treatments available to help.
Acyclovir
Acyclovir is a medication that works by blocking the replication of HSV-1. Dr. Robyn Klein, of the Washington University School of Medicine, writes in UpToDate that acyclovir is the mainstay of treatment for many HSV infections and is in fact the most commonly prescribed medication that works against viruses. While studies have not proven that acyclovir treatment is necessarily beneficial to everyone, some studies have shown that in adults who are especially prone to cold sores, this medication may help. For instance, one study, published in 1993 in the medical journal "Annals of Internal Medicine," focused on adults who had more than 6 outbreaks of cold sores a year. The authors of the study showed that taking 400 milligrams of acyclovir twice daily helped to significantly decrease the number of recurrences of cold sores by about 50 percent. However, in patients with healthy immune systems, the typical treatment is to apply a 5 percent acyclovir ointment to the cold sore, four times daily, for 10 days. Side effects include inflammation at the application site, dry skin or lips and itchiness around the area of application.
Valacyclovir
Valacyclovir is an antiviral medication that is closely related to acyclovir; when taken, it is converted by the liver and intestines to acyclovir. Dr. Kimon Zachary, of Harvard Medical School, writes in UpToDate that valacyclovir may be considered an alternative to acyclovir. Since it is broken down into acyclovir, this seems like a reasonable conclusion; however, it is important to note that valacyclovir has not been studied as extensively as its close relative acyclovir. A potential benefit of valacyclovir is that taking it is more convenient: rather than an ointment taken four times daily, the recommended dosage is 2g, taken by mouth twice daily, for one day. Side effects of valacyclovir include headaches, nausea, abdominal pain and increased liver enzyme levels.
Docosanol
Docosanol (brand name Abreva) is another antiviral medication that is used for the treatment of cold sores. It works by preventing the virus from entering the cells of the human body; without being able to enter the cell, the virus cannot reproduce. Similarly to acyclovir ointment, 10 percent docosanol cream is meant to be applied directly to the cold sore five times a day, up to 10 days or until the cold sore is healed. According to the product information on Abreva, it is recommended that the cream be applied as soon as symptoms begin. The online pharmacology database MicroMedex reports that side effects of docosanol include rare reports of rash, itching, and dry skin as well as stinging and burning at the application site.
References
- "Annals of Internal Medicine"; Oral acyclovir to suppress frequently recurrent herpes labialis. A double-blind, placebo-controlled trial; J.F. Rooney; February 1993
- MicroMedex: Docosanol
- Abreva in Action
- "UpToDate"; Denise S. Basow; 2010
