Cold Sore I

Cold sores, also called fever blisters, are fluid-filled blisters that form at the edge of the mouth, inside the mouth, and sometimes on the chin, cheeks, or upper lip.  These blisters will burst, crust, and heal over without leaving a scar.  They can be painful, and often come after a period of itching, tingling, or burning at the site of the blister. 

              Cold sores are caused by a virus called herpes simplex.  This virus is transmitted through bodily fluids like saliva and genital secretions.  Herpes simplex prefers to attack mucous membranes, and can infect the mouth, both inside and out, the nose, the eyes, and the genital areas.  The virus can also appear on fingers, which is called herpes whitlow.  This virus lives inside nerve cells that connect to areas where outbreaks occur.  Because the virus lives inside your cells, there is no way to get rid of it, and cold sores can come back.  Things that can trigger a recurrence of cold sores include stress, too much sunlight, an infection like a cold or the flu, hurting the affected area, a change in your immune system, menstruation, or nothing at all.  There is no cure for cold sores, but there are medications that can speed up healing time and lessen the pain of a cold sore.

              The most effective medications for cold sores are the ones taken by mouth.  These reach the nerve cells where the virus is being made better than topical medications.  They can decrease the length of time it takes a cold sore to heal by more than a day.  They work best if taken during the prodrome period.  Medications taken by mouth include Zovirax (acyclovir), Valtrex (valacyclovir), and Famvir (famciclovir).  They are usually taken only for a few days.  If you have recurrences often, your doctor may suggest taking daily, or suppressive, therapy with one of these medications.  All the medications are considered safe and effective, with few side effects.

              Topical medications include Zovirax cream (acyclovir) and Denavir (penciclovir).  These medications decrease healing time by half a day, and decrease the pain from the cold sore.  They work best when used at the first sign of a cold sore (the prodrome).

              Only one medication is available over the counter that has been proven to decrease the duration of a cold sore.  Abreva (docosanol) decreases healing time by half a day when applied at the first sign of a cold sore (prodrome). 

              Because cold sores are caused by a virus, they can be transmitted from person to person.  When you have a cold sore, or feel the prodrome coming on, wash your hands every time you touch the cold sore or the area around the cold sore.  Be very careful not to touch your eyes after touching the cold sore.  Do not share eating utensils, cups, or toothbrushes with anyone.  Do not kiss anyone until the cold sore has fully healed. 

              While cold sores cannot be fully prevented, you can decrease the number of outbreaks.  Lip balm with sunscreen can help prevent outbreaks.  Eating a well-balanced diet and reducing stress can help as well.  L-lysine, vitamin C, E, and B12, citrus bioflavinoids, and probiotics have been marketed to help prevent recurrences of cold sores, but there is no scientific data to prove that they work.