Are Cold Sores Contagious?

Cold sores are contagious, painful welts that can show up on your face or fingers. Learn symptoms, causes, and how to get rid of cold sores.

Every winter at the start of a cold, Ruth Greene would get a cold sore on her upper lip. It was hideous. No tween or teenage girl wants to be seen with a blister on her lip.

“It was an annual thing,” she said, “and I hated it. I felt a cold coming on and this reddish bump would appear on my lip.”

The cold sore, also called a fever blister, lasted almost two weeks, about the length of her annual cold. She was self-conscious about it, too.

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What causes cold sores?

Cold sores are caused by the herpes simplex virus (HSV). There are two types of herpes simplex viruses. Type 1 (HSV-1) often cause cold sores. Type 2 (HSV-2) usually causes genital herpes. They’re similar in appearance. It’s also possible for type 1 to cause sores on the genitals and for type 2 to cause sores on the mouth.

Are cold sores contagious?

Cold sores can spread easily, and according to Mark Kaufmann, a dermatologist and MD at the Icahn School of Medicine at Mount Sinai in New York City, cold sores are very contagious. “About 10 percent of people who are infected with type 1 herpes simplex will develop a cold sore within one to two weeks.”

How long do cold sores last?

From the moment you feel a slight tinge or itching around your mouth until they are completely healed and gone, cold sores are contagious. They’re at the height of contagion when they burst and fluid seeps out. 

Greene is in her early 30s and hasn’t had a recurrence for a number of years — about five. “I remember the tingling and, before I saw anything on my lip, I knew a cold sore was coming,” she said. “I went through this almost two-week period where it would bloom, rupture, scab over, and then vanish.”

Greene described pretty closely the life of a cold sore. When a scab forms, eventually it will fall off and the area around it will heal. Kaufmann said that even when a scab forms, the cold sore is still contagious.

How cold sores are contagious?

You can infect others by kissing, sharing cosmetics, or sharing food. Cold sores can also be caused by a fever, cold, over exposure to the sun, stress, menstruation, HIV/AIDS or a weakened immune system, eczema, chemotherapy, and dental work.

Once you get the virus, it can remain dormant in your body and never reappear, or it can appear repeatedly. If you have a cold sore, you can apply over-the-counter (OTC) ointments available at most drugstores. They won’t cure your cold sore, but can lessen the severity.

How to get rid of cold sores

OTC remedies work best when they are applied at the first sign of a cold sore; you’ll have to administer them several times a day. Instructions are on the tube or jar; it comes in cream or ointment form.
Some cold sores are also treated with prescription antiviral medications. If you have an ongoing history of having cold sores talk to your doctor; he may prescribe an oral antiviral medication.

To keep from spreading cold sores to other people, wash your hands often, and don’t shake hands or touch other people. Never share drinks, food, lip balm, or anything else you may put in your mouth. If you do share something, you’ll spread the virus.

Other ways to get rid of cold sores include applying zinc oxide lip balm when you’re in the sun and avoid kissing anyone with a cold sore. If you notice that you get a cold sore when you’re experiencing stress, try meditating or other relaxation techniques.

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