Cold sores: What are they, what causes them — and how to get rid of them

·5-min read

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Red bubbles of virus herpes on lips of a woman in light pink t-shirt, lower part face is seen, which she touches with her finger. Medicine, treatment. White background. Horizontal with copy space
An expert explains why some people get cold sores and others don't. (Image via Getty Images)

This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. Contact a qualified medical professional before engaging in any physical activity, or making any changes to your diet, medication or lifestyle.

Anyone who’s ever developed a cold sore knows just how painful and annoying they can be.

Often, the unwelcome guests don’t come unannounced — you’ll often feel the cold sore before actually seeing it. What may come as a surprise, however, is just how common cold sores really are.

What are cold sores?

Cold sores are a cluster of fever blisters, typically around the mouth, caused by the herpes simplex virus (HSV). 

According to Dr. Monica Li, a double board-certified dermatologist in Vancouver, a majority of the population has the herpes virus inside their bodies in a dormant state. One report estimates that 89 per cent of Canadians have been exposed to the herpes simplex virus, while the Cold Sore Guide estimates 46 to 60 per cent of people will experience a cold sore outbreak. 

On many occasions the virus can cause inflammation and a localized reactivation appears on the skin’s surface in what we refer to as cold sores. 

Cold sores can be painful, but they usually heal within one to two weeks. (Image via Getty Images)
Cold sores can be painful, but they usually heal within one to two weeks. (Image via Getty Images)

“It just depends on if the immune system is able to keep the virus dormant and everybody’s immune system may differ and also may differ at different time points,” said Li in an interview with Yahoo Canada. “Generally, if cold sores recur they recur in the exact same spot.”

What causes cold sores to flare up?

Sun exposure, stress, a viral infection or changes in the immune system can all lead to a cold sore flare up. Some experts believe the change from being exposed to harsh winter temperatures to warm spaces indoors can trigger the herpes virus to reoccur. 

Many people will experience symptoms like burning, itching or throbbing days before the cold sore actually appears. People who experience recurring cold sores can often spot the signs of an upcoming outbreak, and begin treatment before a blister develops. 

It’s not clear cut why some people can get a cold sore and then never get one again, while others can experience multiple episodes a year.

“Patients ask me this all the time. It’s not because they’re dirty people or not clean or promiscuous; it’s not that,”Li explained. “It’s just so common and sometimes we don’t even know where we get the virus from.”

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Is there a cure for cold sores?

There is no cure for cold sores, but there are treatments that can help ease the pain.

Cold sores typically heal after one or two weeks, however there are anti-viral medications available through prescription or over the counter options to help speed up the healing process. Putting ice on the sore or sucking on ice chips can also help alleviate any discomfort during the outbreak. 

Avoiding acidic foods like tomatoes, oranges and grapefruits as well as super salty and spicy foods can also help avoid any pain or stinking from cracked skin around the sore, which can be treated by applying petroleum jelly to the area to maintain moisture. 

“In theory, if things are viral and if there isn't too severe of a presentation, they can go away on its own. The body can gradually get rid of the symptoms and get rid of the cold sores, so you could choose not to treat it," Li explained. “The only issue when you’re not treating a cold sore or trying to prevent one is that sometimes because of the degree of inflammation there can be scarring.”

Applying cold sore medication at the first signs of blistering can help speed up the healing process. (Image via Getty Images)
Applying cold sore medication at the first signs of blistering can help speed up the healing process. (Image via Getty Images)

If you want to be proactive and prevent scarring, Li suggests booking an appointment with a dermatologist within the first 72 hours of an outbreak. According to Li, it's crucial to receive treatment within the 72 hour window because “many of the medications are just not that effective once it’s beyond three days.”

When to see a dermatologist or doctor about a cold sore 

Aside from preventing scarring, there are times when you’ll want to see a doctor or dermatologist, right away to prevent further complications.

"If for instance someone has eczema, there can be a bad outcome if the eczema patches get infected by the herpes [virus],” Li said, adding that people with eczema who experience cold sores should visit a dermatologist right away.

Aside from appearing near the mouth, in rare instances a cold sore may appear on other parts of the face and body. If someone develops a cold sore near or in the eye they should seek medical attention to prevent possible vision damage or further bacterial eye infections. 

Are cold sores contagious?

Cold sores are highly contagious, especially during an outbreak. To help prevent passing your cold sore to others, it's important to avoid kissing or sharing cups and straws with anyone during an outbreak. Cold sores are considered contagious when there’s still fluid inside the blister; it's the fluid that contains the herpes simplex virus.

It's important to avoid touching your cold sore and keep your hands clean to prevent spreading the virus to others. (Image via Getty Images)
It's important to avoid touching your cold sore and keep your hands clean to prevent spreading the virus to others. (Image via Getty Images)

People with active cold sores should avoid touching the area as much as possible and frequently wash their hands or use hand sanitizer to prevent potentially spreading the virus to everything you touch. 

Li recommends using a fresh, clean cotton swab each time you apply medication to the sore can help prevent cross-contamination, which can lead to an infection.

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