What triggers cold sores to flareup?

Herpes simplex virus-1 (HSV-1), the “cold sore” virus, is extremely common — in fact, it’s believed to be present in as much as 90 percent of the world’s population and more than half of all Americans. Once infected with HSV, the virus never leaves your system and, when triggered, can cause cold sores, brain inflammation or a dangerous recurring eye condition. HSV infection has also been connected with the progression of Alzheimer’s disease.

But researchers are finding out what causes HSV-1 to flare up, which could lead to new ways to prevent these recurrences…

Gaining a better understanding of the cold sore virus

Researchers at the University of Virginia recently examined exactly how things like stress, illness and overexposure to the sun can trigger unwanted HSV-1 outbreaks.

“Herpes simplex recurrence has long been associated with stress, fever and sunburn,” says researcher Dr. Anna R. Cliffe of UVA’s Department of Microbiology, Immunology and Cancer Biology. “This study sheds light on how all these triggers can lead to herpes simplex-associated disease.”

Once HSV-1 has entered the body, it lays dormant inside neurons until something triggers its reactivation. Cold sores, or fever blisters, are one of the most common signs of HSV reactivation. It can also be reactivated in the eye in a condition called herpes keratitis, which if left untreated can lead to blindness. And in rare cases, HSV-1 reactivation can cause encephalitis, a potentially fatal inflammation of the brain.

While it’s been known that recurrences of HSV-1 can be set off by stress, illness or sunburn, what’s not been clearly understood is exactly what causes the virus to reactivate. Cliffe and her team discovered that when neurons containing HSV-1 were exposed to stimuli that cause “neuronal hyperexcitation,” the virus senses this change and takes the opportunity to reactivate.

Utilizing a model developed using mouse neurons infected with HSV-1, the researchers found the virus takes over the body’s release of a critical immune response to inflammation or stress: the release of the cytokine interleukin 1 beta. When epithelial cells in the skin and eye experience damage, such as that caused by ultraviolet light, they release interleukin 1 beta. This cytokine then increases excitability in the affected neurons, which then can cause HSV-1 reactivation.

“It is really remarkable that the virus has hijacked this pathway that is part of our body’s immune response,” Cliffe says. “It highlights how some viruses have evolved to take advantage of what should be part of our infection-fighting machinery.”

A more complete picture needed

While the insights help increase understanding of how HSV-1 interacts with neurons and the immune system, the researchers say more study is needed to fully understand the potential factors involved in herpes simplex disease. They note that these factors could vary depending on the virus strain or type of neuron infected, and that it’s still not known if HSV-1 changes how neurons respond to cytokines like interleukin 1 beta.

“A better understanding of what causes HSV to reactivate in response to a stimulus is needed to develop novel therapeutics,” Cliffe says. “Ultimately, what we hope to do is target the latent virus itself and make it unresponsive to stimuli such as interleukin 1 beta.”

Until then, the best defense is not to become infected with HSV-1. Wash your hands frequently and avoid close contact with someone who has a cold sore or thinks they’re about to have a cold sore. Also, do not share their personal items such as towels, razors or eating utensils.

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Controlling cold sore flareups

If you already have HSV-1, you can take measures to prevent outbreaks like cold sores. As with most illnesses, it’s important to eat well, exercise and get enough sleep to manage stress and give your body stamina to fight off sickness. In the case of HSV-1, it also helps to protect your face and lips from sun exposure by using sunscreen and wearing a wide-brimmed hat.

When a cold sore does appear, you can prevent spreading HSV-1 by practicing good hygiene. Try not to touch it, and if you do, make sure you wash your hands right away. That will help keep you from spreading it to other parts of your body, or to other people. Also, change your toothbrush and throw out any creams, balms, ointments or makeup you’ve been using on your face or lips.

We’ve written before about natural ways to treat cold sores, including applying licorice root, peppermint oil, vanilla oil or extract, tea tree oil, lemon balm or manuka honey directly to the sore. Aloe vera gel also can help a cold sore heal and in lab studies has shown the potential to fight viruses, including HSV.

Thymoquinone (TQ), one of the active compounds in black cumin seed oil, has been studied for exhibiting antiviral properties. It is considered an immune system modulator, meaning it may help balance an overactive immune response. In one study, TQ was found to inhibit the entry and cell to cell spread of HSV-1.

In addition, the essential amino acid lysine has proven in studies to be effective at reducing the severity and duration of cold sores. You can get lysine through supplementation or by eating foods like fish, poultry, legumes and vegetables. Be aware that the amino acid l-arginine can lower levels of lysine, so you may want to avoid foods high in l-arginine if you’re susceptible to cold sores or having frequent flare-ups. L-arginine can be found in chocolate, spinach, nuts and nut butters, lentils and soybeans.

Sources:

Cold Sores: Here’s How Stress, Illness and Even Sunburn Trigger Flareups — UVAHealth

Neuronal hyperexcitability is a DLK-dependent trigger of herpes simplex virus reactivation that can be induced by IL-1 — eLife

Reducing Your Risk of Cold Sores (Herpes Simplex Type 1) — Winchester Hospital

N Vitro And In Silico Evaluation Of Anti-Herpes Simplex Virus Potentials Of Thymoquinone — Research Gate

How to Get Rid of Cold Sores — WebMD

Carolyn Gretton

By Carolyn Gretton

Carolyn Gretton is a freelance writer based in New Haven, CT who specializes in all aspects of health and wellness and is passionate about discovering the latest health breakthroughs and sharing them with others. She has worked with a wide range of companies in the alternative health space and has written for online and print publications like Dow Jones Newswires and the Philadelphia Inquirer.