Topic Overview

What are cold sores?

Cold sores , sometimes called fever blisters, are groups of small blisters on the lip and around the mouth. Often the first sign of a cold sore is a spot that tingles, burns, or itches. A blister usually forms within 24 hours. The skin around the blisters is often red, swollen, and sore. The blisters may break open, leak a clear fluid, and then scab over after a few days. They usually heal in several days to 2 weeks.

What causes cold sores?

Cold sores are caused by the herpes simplex virus (HSV) . There are two types of herpes simplex virus: HSV-1 and HSV-2. Both virus types can cause sores around the mouth (herpes labialis) and on the genitals ( genital herpes ).

The herpes simplex virus usually enters the body through a break in the skin around or inside the mouth. It is usually spread when a person touches a cold sore or touches infected fluid—such as from sharing eating utensils or razors, kissing an infected person, or touching that person's saliva. A parent who has a cold sore often spreads the infection to his or her child in this way. A person can spread the virus to someone else a few days before the sore appears until the sore is completely healed. Cold sores can also be spread to other areas of the body.

What are the symptoms?

The first symptoms of cold sores may include a spot that tingles, burns, or itches around your mouth and on your lips. You may also have a fever, a sore throat, or swollen glands in your neck or other parts of the body. Small children sometimes drool before cold sores appear. After the blisters appear, the cold sores usually break open, leak a clear fluid, and then crust over and disappear after several days to 2 weeks. For some people, cold sores can be very painful.

Some people have the virus but don't get cold sores. They have no symptoms.

How are cold sores diagnosed?

Your doctor can tell if you have cold sores by asking you questions to find out whether you have come into contact with the virus and by examining you. You probably won't need any tests.

How are cold sores treated?

Cold sores will usually start to heal on their own within a few days. But if they cause pain or make you feel embarrassed, they can be treated. Treatment may include skin creams, ointments, or sometimes pills. Starting treatment right away may get rid of the cold sores only 1 to 2 days faster, but it can also help ease painful blisters or other uncomfortable symptoms.

The herpes simplex virus that causes cold sores can't be cured. After you get infected, the virus stays in your body for the rest of your life. If you get cold sores often, treatment can reduce the number of cold sores you get and how severe they are.

How can you prevent cold sores?

There are some things you can do to keep from getting the herpes simplex virus.

• Avoid coming into contact with infected body fluids, such as kissing an infected person.
• Avoid sharing eating utensils, drinking cups, or other items that a person with a cold sore may have used.

After you have been infected with the virus, there is no sure way to prevent more cold sores. But there are some things you can do to reduce your number of outbreaks and prevent spreading the virus.

• Avoid the things that trigger your cold sores, such as stress and colds or the flu.
• Always use lip balm and sunscreen on your face. Too much sunlight can cause cold sores to flare.
• Avoid sharing towels, razors, silverware, toothbrushes, or other objects that a person with a cold sore may have used.
• When you have a cold sore, make sure to wash your hands often, and try not to touch your sore. This can help keep you from spreading the virus to your eyes or genital area or to other people.
• Talk to your doctor if you get cold sores often. You may be able to take prescription pills to prevent cold sore outbreaks.