What causes cold sores?

Have you awakened in the morning to find a blister or cluster of small blisters on your lip? These are cold sores, or fever blisters, which are caused by the herpes simplex virus.

The virus isn’t dangerous and can’t be cured — it’s just annoying when it flares up on your lip. Many people have no symptoms from the virus.

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What Are Cold Sore Symptoms?

Generally, a tingling, burning, or itching around your mouth is the first sign that a cold sore is coming. The characteristic blister, which usually forms within a day, may break open and leak fluid, then crust over and heal. A cold sore can last anywhere from a couple days to two weeks. For some people, it can be painful but most often it’s just a nuisance.

How Are Cold Sores Spread?

Are cold sore contagious and how are they spread? Yes, the herpes simplex virus can be passed from person to person. You can spread fluid from a cold sore blister to another person through kissing or by sharing utensils or a razor. It can also be spread to other parts of the body through infected fluid and saliva.

When you have a cold sore, avoid kissing or sharing food and drink with others. Don’t touch the sore, and wash your hands immediately if you do. Cold sores usually clear up in about two weeks, according to the American Academy of Dermatology, so consider them contagious until they are fully healed.

How Can You Treat a Cold Sore?

Cold sores most often go away on their own without treatment. Anti-virus medications, taken orally or applied as creams or ointments, can speed up the recovery time of a cold sore outbreak, but these treatments aren’t cures. These medications work best when started at the first sign of a cold sore.

The herpes simplex virus stays in your body for the rest of your life, but you won’t always have symptoms. Being mindful of your actions when a cold sore pops up will help you keep from passing it on to friends or family.

Learn more about the herpes simplex virus and other  infections at UPMC.


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