Cold Sores

Cold sores, also called fever blisters, are small, sometimes painful blisters that can form on and around the mouth. The medical term for cold sores is oral herpes because they are caused by the herpes simplex virus (HSV).

Herpes simplex virus 1 (HSV-1) is very common. In fact, It is estimated that nearly 90% of adults in the United States have been infected with it by age 50 (although not everyone gets cold sores).

This article will explain the symptoms of cold sores, what causes them, how they are treated, and how to prevent outbreaks.

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Symptoms of Cold Sores

Many people who have HSV-1 never experience any symptoms. If you do have symptoms, they may include:

• Fluid-filled blisters on the outside of the mouth around the lips
• An itchy or tingling sensation in the area shortly before the blisters appear
  
• Fever and swelling of the lymph nodes, similar to other viral infections (though these symptoms are less common)

The blisters may be confined to one area only or appear in several areas at a time. They typically last from seven to 10 days, during which time they will break open, ooze fluid, and form a crust before healing.

Causes of Cold Sores

Most cold sores are caused by the HSV-1 virus, and most people who get the virus are exposed during infancy or childhood through skin-to-skin contact with an adult with the virus, though it is possible to be infected during adulthood as well. It can be transmitted by:

• Kissing
• Touching the skin
• Sharing things like lip balm, razors, or silverware

Once you are infected with HSV-1, the virus "lives" in your nerve cells permanently, causing periodic outbreaks of cold sores.

Common triggers of cold sores include:

• Sun exposure
• Stress
• Fever
  

How to Treat Cold Sores

There is no cure for HSV, but treatments are available. Sores and blisters typically clear up on their own, but treatment is often used to reduce the severity and duration of outbreaks.

Antiviral creams and ointments can help with itching, and oral antiviral medications, including Zovirax (acyclovir), Famvir (famciclovir), and Valtrex (valacyclovir) can shorten an outbreak. When oral medication is taken on a daily basis, it not only can help with outbreaks, but it also can prevent those who are infected from infecting others.

You can also ease the discomfort of symptoms by:

• Applying ice or a warm washcloth to the sores to help ease pain
• Avoiding hot beverages, citrus fruits, and spicy foods
• Taking a pain reliever such as Tylenol (acetaminophen)
  

Complications and Risk Factors Associated With Cold Sores

In some cases, the herpes virus can spread to the eyes, causing ocular herpes, or herpes keratitis. Symptoms can include discharge or a “gritty” feeling. Without treatment, ocular herpes can cause scarring in the eye and affect vision.

In people who have a weakened immune system due to cancer or HIV infection, oral herpes can cause a systemic (widespread, whole-body) infection.

Are There Tests to Diagnose Cold Sores?

Healthcare providers can typically diagnose a case of herpes by looking at the sores. A swab may be taken and sent to a laboratory for confirmation. If no sores are present, a blood test can detect HSV.

When to See a Healthcare Provider

Most cold sores are not serious, however they can be uncomfortable. You should call your healthcare provider if:

• Your symptoms are severe or don't go away after a couple of weeks
• You have sores or blisters near your eyes
• You have a weakened immune system

Summary

Cold sores are clusters of small, fluid-filled blisters that form on or around the mouth. They are caused by the herpes simplex virus (HSV-1) While there is no cure for HSV, there are treatments like antiviral creams and medications that you can take to help shorten the outbreak, address symptoms, and reduce the likelihood of infecting others. 

A Word From Verywell

Cold sores are very common. They can be uncomfortable and can make you feel self-conscious. Knowing what triggers your outbreaks can help you prevent cold sores from forming, and oral and topical anti-viral medications can shorten their course.