A cold sore, or herpes labialis --- herpes of the lips, is caused by herpes simplex virus type 1, or HSV-1. The virus remains in the body after the first infection, and certain factors trigger the "sleeping" virus to awake, causing a new cold sore. The most common location of cold sores is the lips, according to the Mayo Clinic. The first sign of an outbreak is tingling on their lips, after which painful fluid-filled blisters appear.
Initial HSV-1 Infection and Recurrence
More than 95 percent of returning cold sores are caused by the HSV-1. After the first infection, the body is not able to clear all of the virus, and some of it stays in a nerve near the cheekbone. In some people the virus remains inactive and never causes a cold sore. In others, however, the virus travels to the lips during an outbreak, causing new cold sores to appear.
Transmission of the HSV-1
Cold sores are contagious, and people who have them can transmit the HSV-1 at any time symptoms are present. People get the first cold sore from others who have active herpes infection at the time of their contact. It can be mucous membrane or skin-to-skin contact, such as kissing, which is probably the most common way of transfer, or by the sharing of items such as silverware, drinks, razors and towels. Affected people can also transfer the virus from their lips to other parts of the body.
Cold Sore Triggers
Several factors can trigger cold-sore outbreaks in people infected by HSV-1. In a 2005 study, researchers found that patients connected outbreaks with emotional stress, illness or trauma and sun exposure. According to the World Health Organization, UV radiation might decrease the protective power of the immune system, making it unable to keep HSV-1 under control and causing the cold sore outbreak. Other triggers may include fever, cold, flu, fatigue, injury to the skin around the lips, including cracked and dry lips, exposure to cold weather and wind and hormonal changes, such as menstruation or pregnancy.
Avoiding Spreading the Virus
Because cold sores are contagious, people should avoid kissing and skin contact with others while having blisters, from which the virus can spread easily. Also, silverware and cups, towels, lip balm and razors can spread the virus, so the Mayo Clinic recommends avoiding sharing these items. Proper hand hygiene is also recommended during an outbreak, especially before touching another person or other body parts.
Avoiding the Triggers
People who suffer from cold sores should try avoiding conditions that stress the body and potentially cause outbreaks. The conditions to avoid include insufficient sleep, emotional stress, cold or the flu. Cold and flu can sometimes be prevented by hand washing, rest, healthy diet and C vitamin supplementation. The best way to prevent the flu is to get a flu shot. Also, it is helpful to apply sun block to the lips and face before prolonged sun exposure.
References
- MayoClinic.com: Cold Sore Causes
- eMedTV.com: Cold Sore Causes
- "Journal of the Canadian Dental Association"; Recurrent Herpes Simplex Labialis: Selected Therapeutic Options; G. Wayne Raborn, DDS, MS, Michael G. A. Grace, PhD; September 2003
- World Health Organization: Does UV interact with the immune system?
