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February 19, 2021

What causes cold sores to return? New research offers a deeper understanding

A particular protein may hold the key for preventing flare ups

Wellness Infections
Cold Sore recurrence Gabriel Doti/Pixabay

Most cold sores will heal without treatment, but prescription antiviral pills and creams have been proven to accelerate healing and limit the severity and frequency of future outbreaks.

It's no secret that cold sores tend to pop up during periods of stress and then take another two or three weeks to go away. 

But new research offers a clearer understanding of why stress, illness and sunburn prompt cold sores, the painful result of a lifelong infection of the herpes simplex virus. 

More than half of Americans are carriers of the virus, which lies dormant in the nerve cells of their skin in between flare-ups.

"Herpes simplex virus hides in nerve cells for life, so once you have herpes simplex you always have it," Anna Cliffe, a microbiology professor at the University of Virginia, told U.S. News & World Report. "Sometimes, it comes out of hiding, and this can cause clinical disease, like cold sores, eye disease and genital lesions."

Cliffe and her research team found the virus becomes reactivated when neurons — cells that send messages to other parts of the nervous system — become triggered to constantly fire at full strength. 

The main culprits are a pair of proteins — DLK and interleukin 1. The latter is released when a person becomes stressed or falls ill with a fever. It also can be released when the skin is exposed to ultraviolet light. But without the release DLK, the virus won't reactivate. 

That may make DLK a good target for preventative therapies, researchers said. Their study was published in the journal eLife.

"Our long-term goals are to understand how to make sure herpes simplex cannot respond to these signals and therefore, prevent reactivation occurring," Cliffe said. 

There is not a known cure for a herpes simplex virus infection. While most cold sores can heal without treatment, prescription antiviral pills and creams have been proven to accelerate healing and help limit the severity and frequency of future outbreaks.

Preventing cold sores

Cold sores — often known as fever blisters — usually pop up in small groups on or around the lips. Scabs form after the blisters break, but they usually don't leave scars. 

Cold sores are contagious even when they aren't visible and can be spread by people in close contact, especially through kissing and oral sex. The herpes simplex virus also affects the genitals, the Mayo Clinic says.

To prevent cold sores from spreading, experts instruct people to wash their hands carefully and avoid kissing and skin contact with others. They also advise against sharing personal items, especially utensils, towels and lip balms. 

The first onset of symptoms may not occur for up to 20 days after exposure. Recurrences tend to occur at the same spot each time and generally are less severe than the first breakout, according to the American Academy of Dermatology Association.

The first time people get cold sores, they may experience fever, painful gums, sore throat, headache, muscle aches and swollen lymph nodes. Common triggers of flare-ups include another viral infection, hormonal changes, stress, fatigue, sunburn, a weakened immune system and injury to the skin.

Sometimes the herpes simplex virus can cause complications in the fingers, eyes and larger swaths of skin. Experts urge people to seek medical attention immediately if this happens.

Doctors may prescribe an antiviral medication for people who have frequent flare-ups or are at high risk of complications. 

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