The #1 Thing Most People Don't Know Can Cause a Cold Sore, According to Dermatologists

Woman with a cold sore

When we say "cold sore," you probably know what we're talking about: the annoying red bump on your lip that itches and burns. Cold sores are pesky, and uncomfortable, and can make you feel self-conscious.

Upon Googling how the heck it got there (in hopes you can prevent it from ever coming back), you might learn about herpes simplex virus (HSV). Between 50 percent and 80 percent of American adults have this type of herpes, HSV-1.

What’s probably more important to pay attention to, though, is what triggers an outbreak. HSV can lie dormant in the body, but when a trigger happens, that’s when you see the cold sore pop up on your face.

The triggers are many, maybe a bit surprising and are all too relatable. A major one, according to dermatologists, is stress.

The #1 Unexpected Cause of Cold Sores

Yep, stress is more than just a mental thing! “Stress, whether it is physical stress on the body or emotional stress, can impact the immune system and make someone more susceptible to cold sores,” explains Dr. Marisha Garshick, MD, FAAD, a leading board-certified dermatologist at MDCS Dermatology in the Northeast.

“When the immune system is compromised, the virus can become active and cause outbreaks,” adds Dr. Connie Yang, MD, FAAD, a cosmetic dermatologist at PFRANKMD by Dr. Paul Jarrod Frank.

It’s important to note that “stress” is a super wide umbrella; it can encompass a wide range of contributors.

For example, emotional stress might come from your boss putting pressure on you at work or a fight with your partner. This type of stress might present as a headache, feeling like your heart is racing, irritability, depression and many other signs.

Physical stress can come from a lack of sleep or even hormonal fluctuations, like the ones people experience around their menstrual cycles. “Large fluctuations in hormones can cause stress on the body, which can contribute to cold sores,” Dr. Garshick explains.

Dr. Yang says that poor sleep and hormonal fluctuations—and UV radiation—can all suppress or weaken the immune system too.

But don't forget that these examples only scratch the surface.

Related: Calm Your Mind and Find Peace With These 25 Bible Verses About Stress

How to Address Stress-Causing Cold Sores

If you’re all too familiar with cold sores, Dr. Garshick shares three main pieces of advice: to keep an eye out for them when you’re sick or stressed, to start a medicine like valacyclovir when you notice symptoms starting and to implement regular stress management techniques.

In case you weren't sure, signs that a cold sore is coming include tingling, itchiness and a burning sensation around the lips. In this case, valacyclovir can help as it's an antiviral drug used to slow the growth and spread of the herpes virus.

As far as stress management, it’s important to engage in those practices when you’re stressed and when you’re not as a preventive measure. You might want to meditate, say some compassionate statements to yourself, chill for a bit on the couch, or do whatever else relaxes your mind and body.

That’s easier said than done, though, right? Dr. Yang acknowledges that “taking measures to decrease stress on the body can be helpful, but may not be feasible or realistic for everyone.” If that’s the case for you, she suggests being aware of when your body is more prone to outbreaks and having medication on hand to minimize symptoms (more on that later!).

Related: 9 Ways to Begin Your Emotional Regulation Journey as an Adult, According to a Licensed Therapist

Other Surprising Causes of Cold Sores

Other cold sore causes may be unexpected too, though they could be more loosely linked to stress.

One example is sun exposure. It can “trigger cold sores either by reactivating the virus or by weakening the immune system,” Dr. Marshick says. “For this reason, it can be helpful to wear sun protection regularly.”

Similarly, extreme temperatures (hot and cold) can also cause cold sores, she says. Cold, dry air can dry out your lips while hot, humid weather can act as a catalyst for the virus.

Dr. Yang notes that UV radiation can also cause damage and inflammation in skin cells and influence the nerve cells where the virus resides, which reactivates it.

Related: Is That Thing on My Face a Cold Sore or Pimple? Here’s How to Know the Difference—and How to Treat Each

Other Ways to Prevent and Treat Cold Sores

Both dermatologists agree that your best bet for effective treatment is taking an antiviral medication, such as Valtrex (AKA valacyclovir), at the first onset of symptoms.

“This works best when taken before blister formation, so as soon as you develop even a hint of that familiar tingling sensation,” Dr. Yang says. “Even if taken after blister formation, it can halt progression and speed up healing of the cold sore.”

Other products Dr. Garshick says can help are ointments, like Vaseline, as they “minimize scab formation and provide a protective barrier.”

While these treatments are generally recommended by dermatologists, don’t forget about the value of individualized assessments of needs too. Dr. Yang says prevention can depend on a person knowing and avoiding their specific triggers.

Also, if you get these outbreaks more than three times a year, she says, you may need a chronic suppressive dose of oral antiviral. Per usual, just talk to your doctor or dermatologist about what’s best.

So, while a host of stress forms can cause a cold sore to show, you’re not powerless. Prevention and treatment through stress management, antivirals and ointments, for example, all provide major, ongoing help.

Next up, check out this list of 10 ways to get rid of a cold sore faster.

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