Cold Sore

Overview

Cold sores are red, fluid-filled blisters that appear near the mouth or on other areas of the face. In rare cases, cold sores may appear on the fingers, nose, or inside the mouth. There is no cure for cold sores, and infections tend to reoccur without warning. Sores are contagious and may persist for more than one week.

What Causes Cold Sores?

Herpes simplex type 1 virus usually causes cold sores, and herpes simplex type 2 virus generally causes genital herpes. The actual sores are similar in appearance for both forms of the virus.
It is possible (though rare) for herpes simplex type 1 to cause sores on the genitals, and for herpes simplex type 2 to cause sores on the mouth.
Visible sores are contagious, but herpes may be spread even when sores can’t be seen. You can catch the herpes simplex virus by coming in contact with infected individuals. This may happen through kissing, sharing cosmetics, or sharing food. Oral sex may spread both cold sores and genital herpes.

Reinfection

Once you catch herpes simplex virus, it can’t be cured. Even after sores have healed, the virus remains dormant in your nerve cells, and new cold sores can appear at any time. Some affected patients report more frequent outbreaks when their immune systems are weak, such as during illness or times of stress.

Recognizing a Cold Sore

You may notice a tingling or burning sensation on your lips or face several days prior to the emergence of a cold sore. Once the sore erupts, you will see a red, raised blister full of fluid, which will usually be painful and tender to the touch.
The sore will remain for two to three weeks, and it is contagious until it crusts over. Your first cold sore may not appear for up to 20 days following infection with the herpes simplex virus.

In addition to one or several sores, you may experience any of the following symptoms during an outbreak:

• fever
• muscle aches
• swollen lymph nodes

Touching your cold sore before touching your eyes can cause eye infections. You should seek immediate medical care if you develop an eye infection during a cold sore outbreak. This is because infections caused by herpes simplex can lead to permanent vision loss if not treated promptly.