Cold sores: What are they, how do you get them and what can you do?

There’s little that’s more unsavoury than getting a cold sore — they’re oozy, crusty and really hard to cover up. But as horrifying as it can be to get one, the reality is you’re not alone, by a long shot.

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The World Health Organization estimates that 3.7 billion people under the age of 50 (67 per cent of the population) has the HSV-1 infection globally.

What is a cold sore?

It’s an oral version of the herpes virus (which we commonly associate with the dreaded genital version) and follows the same pattern: it’s very contagious and you’ll never be rid of the virus. But it’s treatable.

HSV-1 (or herpes simplex virus type 1) is associated with cold sores, and is transmitted through mouth-to-mouth contact or oral secretions, while HSV-2 causes genital herpes via sexual contact. While they used to be regarded as two separate viruses, it is now known that HSV-1 or cold sores can cause genital herpes and vice versa.

“The challenge is that we’re very good at getting them and never getting rid of them,” Hanna says. “However, it’s not necessarily true that everyone who is exposed to cold sores will get one. We can’t say it definitively, but there’s a host factor that allows it. You could be a carrier but your immune system recognizes it as foreign and walls it off. Getting a cold sore doesn’t necessarily denote a defective immune system but a permissive one.”

Tweet This Click to share quote on Twitter: "The challenge is that we're very good at getting them and never getting rid of them," Hanna says. "However, it's not necessarily true that everyone who is exposed to cold sores will get one. We can't say it definitively, but there's a host factor that allows it. You could be a carrier but your immune system recognizes it as foreign and walls it off. Getting a cold sore doesn't necessarily denote a defective immune system but a permissive one."

HSV-1 lives in the nerve roots where it’s usually dormant, but when it flares up, it irritates the nerve and incites a burning or stinging sensation. A day or so later, you might notice a red spot and then you could feel a little cluster of water-filled bubbles on or near your lip (or what the dermatology community calls “dew drops on a rose petal”).

How can you treat it?

The duration of a cold sore depends on how quick you act to temper it. Doing nothing, it can take up to two weeks to fully run its course, from formation to blistering to crusting and finally disappearing. But caught early, you can use a topical antiviral medication or an oral one to shorten its lifespan or even shut it down entirely.

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“If someone gets them all the time, say six or more times a year, we’ll put them on a lower dose of an oral antiviral medication,” that they take every day.

In some cases, severe or very recurrent cold sores could leave little scars or pits in the skin.

What causes them to erupt?

Sometimes there’s no trigger at all for a cold sore to come out; other times, they can be triggered by sun exposure, physical trauma like picking or scratching, or a compromised immune system from fighting off another infection or virus (hence the term “cold sore”). They’re also common in people with immunocompromised diseases like HIV, transplant patients and people on a lot of medications.

How can you know if you have the virus?

The first sign is an active sore, but if the virus is dormant and you don’t show any symptoms, detecting it can be tricky.

How does it get passed on?

As mentioned earlier, HSV-1 is transmitted through oral contact (kissing, or sharing utensils, drinking glasses or lip care products), and HSV-2 is passed on through skin-to-skin contact, usually sexual. In the vast majority of cases, the absence of an active lesion means you can’t pass on the virus, but in very few cases it can still be transmitted — a fact that means you should avoid too much contact with the most vulnerable people, like newborn babies.

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“Newborns and premature babies don’t have a fully developed immune system, so you have to be really cautious if you have the herpes virus. There’s a rate of incidence, albeit exceedingly low, of transmission,” Hanna says. “If you’re a mom and you have a cold sore, you want to protect your baby from exposure, especially between the ages of three to six months.”

As such, always avoid kissing newborns on their mucous membranes (like the mouth, nose and eyelids), especially if you have an active cold sore. Overall, doctors do advise avoiding kissing babies in these areas, as well as their mouths and hands, until they’ve reached three months of age and their immune systems are stronger. If you must, always kiss a baby on the back of their head.