Common Cold Sore Triggers Explained

You may already know some of your triggers if you tend to get cold sores (oral herpes). Maybe you experience an annoying outbreak whenever you’re sick or when work gets stressful.

But could anything else be contributing, like the weather or the foods you eat? We asked internal medicine specialist Jameelah Strickland, MD, about cold sore triggers.

Understanding cold sores

Cold sores are the result of a herpes simplex virus (HSV) infection, the same virus that causes genital herpes. HSV spreads from person to person. Once you catch the virus, it stays in your body forever.

But having HSV doesn’t mean you’re in for nonstop cold sores. “HSV can remain in a latent, or resting, state in your body for months or years,” Dr. Strickland explains. “You get a cold sore when the virus reactivates.”

Common triggers for cold sores

Cold sore triggers vary from person to person, but HSV is an opportunistic infection. That means it rears its ugly head when, for whatever reason, your immune system is too weak to fight it off.

Some of the most common causes of a weakened immune system include:

Illness or infection

“Cold sores get their name because they so often appear alongside the common cold,” Dr. Strickland says. “Your immune system struggles to keep the HSV virus dormant because it’s busy addressing the rhinovirus.”

We call them “cold sores,” but any kind of infection can throw your immune system off its game. Fevers do a particularly good job of incubating a cold sore. That’s why you may also hear them called “fever blisters.”

Keep in mind that infections that attack your immune system directly, like HIV, can cause more frequent outbreaks.

Autoimmune conditions

Autoimmune conditions confuse your immune system into targeting healthy tissue, which allows opportunistic infections like HSV to take advantage of the chaos.

Conditions like lupus, Sjogren’s syndrome and mast cell activation syndrome (MCAS) weaken your immune system by overworking it. Cold sore outbreaks are just one of many possible side effects.

Immunosuppression

Your risk of cold sores goes up if you have to suppress your immune system on purpose to treat a medical condition (like cancer) or prevent a complication (like organ rejection). There’s nothing actually wrong with your immune system. You’ve just turned down the dial on it.

The downside? It makes you more susceptible to infections, and to HSV reintroducing itself.

Damaged or cracked skin

When your skin barrier gets damaged, it triggers an immune response — and sometimes, a cold sore. It’s also one of the ways the herpes simplex virus spreads between people.

“Sunburns, rashes, severe acne outbreaks, and even cuts and scrapes can cause an inflammatory response that opens the door for fever blisters in some people,” Dr. Strickland notes.

When your skin barrier is compromised, it takes damaged skin longer to heal. So, you may be sporting that sore a little longer than usual.

Extreme temperatures

Spending time in very hot or very cold weather can wreak havoc on your body — and that stress provides the perfect environment for HSV to reactivate.

“Both extremes can be a problem, but cold weather can also leave the skin on your lips cracked and dry,” Dr. Strickland shares. “That damage further increases the likelihood of getting a cold sore.”

Hormonal changes

Puberty, pregnancy, menstruation and menopause: These and other kinds of hormonal shifts, like imbalances, can sometimes come with a side order of cold sores. (Because fluctuating hormones aren’t annoying enough on their own!)

It may not be the first thing you think about, but your sex hormones actually play a big role in your immune health. Some, like estrogen, boost your immune health. Others, like testosterone and progesterone, suppress your immune response.

Lip injuries and cosmetic procedures

Any kind of trauma to your lips can trigger an oral herpes outbreak — even injuries like bruises that don’t involve broken skin. Ditto for cosmetic procedures like filler injections, permanent makeup, lip flips and more.

If you have a history of cold sores, Dr. Strickland urges you to talk to your provider before having any kind of work done on or around your lips. They may recommend taking antivirals before and after to reduce your risk.

One more thing: Always cancel upcoming cosmetic procedures if you have an active cold sore — even if the procedure doesn’t involve your lips. An active HSV infection will still raise your risk for serious complications.

Lack of sleep

“Sleep deprivation can weaken your immune system and raise your susceptibility to cold sores,” Dr. Strickland says. “It’s just one more reason to make sure you’re practicing good sleep hygiene.”

Stress

Both emotional and physical stress weaken your immune response, setting the stage for an oral herpes outbreak.

“In stressful situations, your body releases hormones like cortisol and adrenaline,” Dr. Strickland explains. “In short bursts, like during emergencies, that’s a really good thing. Long-term stress, on the other hand, causes chronic inflammation. And when your immune system’s working overtime to create all that inflammation, it’s more likely that HSV will reactivate, causing cold sores.”

Food

While you may have read that certain kinds of foods can cause cold sores, there isn’t much scientific evidence to back that up.

The possible exception to that rule? Allergic reactions, especially when they affect the skin on your lips.

“If you have oral allergy syndrome, your lips can itch, swell up, dry out or develop a rash,” Dr. Strickland says. “That kind of damage could trigger an outbreak.”

If you notice that certain foods bother your lips, speak to your provider about it. Otherwise, your diet is unlikely to trigger a cold sore. If anything, eating foods that boost your immune health could help keep them at bay. It certainly can’t hurt!

Final thoughts

Don’t assume that you have to live with cold sores. Knowing your triggers and seeing your healthcare provider can help you manage — and maybe even cut down on — oral herpes outbreaks.

“Antivirals can make a big difference for people who get cold sores regularly,” Dr. Strickland adds. “So, have the conversation. Your provider can help you find the best way to prevent them so they don’t interfere as much with your life.”