Does Sun Light Cause Cold Sores?

Michele Emery, DNP

Medically reviewed by Michele Emery, DNP

Written by Our Editorial Team

Last updated 12/16/2018

There’s a lot to look forward to during the summer. Sunnier weather brings with it weekend camping trips, adventurous hikes, beach days and afternoons at the park — things we think we can all agree are awesome. 

But if you are prone to  cold sores, you should watch out for the sun. Estimates from the World Health Organization (WHO) estimate that around 67 percent of the world’s population under the age of 50 have HSV-1, the virus that leads to cold sores. While cold sores are not caused by sunlight, overexposure to sunlight can trigger outbreaks.

Though the virus is one of the most common in the world, there’s still plenty of misinformation on the web about how to deal with it. To make the warmer months easier for those affected by HSV-1, we’ve put together a guide on how to prevent sunlight from making your outbreak worse.

How Does Sun Light Cause Cold Sores?

The sun is one of many possible triggers for cold sores that include everything from fatigue, illness, and hormonal changes, to even stress    f in some cases. Summer days mean more time outside, which subsequently increases your chance of having your skin damaged by the sun. Exposure to the sunlight’s ultraviolet (UV) rays may trigger a cold sore recurrence.

The sun exudes light rays which go unseen by the eye but impact your body. 

Although these rays promote beneficial nutrient production like vitamin D, they also damage the skin to varying degrees when absorbed. 

If you are already prone to cold sores, you should be particularly careful and learn about ways to stop sun damage before it happens.


You have probably been told from a very young age how vital it is to apply sunscreen. A certain song comes to mind. But its importance can’t be understated — particularly if you have cold sores. 

In general, the FDA recommends that you use broad spectrum sunscreen with an SPF of 15 or higher, even on cloudy days. Generously apply to all uncovered skin and do not forget your nose, hands, feet, outside of your ears, and lips, but avoid your eyes, mouth, and inner ears.

Reapply at least every two hours and apply more often if you’re swimming or sweating. If you’re concerned about titanium dioxide and zinc, there are plenty of organic options like Badger, Alba Botanica and Naturopathica.

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Cold sore treatment that works

Lip Balm

You should regularly apply lip balm to moisturize and protect your lip skin, regardless of how dry or humid  or hot or cold it is outside. In fact, even if it’s cloudy and overcast outside, UV rays  still impact our skin. 

There are lip balms that are specifically meant to help prevent — and treat — a cold sore outbreak like Herpecin L®. If you're going to be in the sun frequently, moisturizing all your skin is a good pro-tip, in general. We have stuff for that. 

Tiger Grass

In recent years, Tiger Grass has grown in popularity — but has been used in folk medicine for hundreds of years. Despite the lore surrounding them, research supports Tiger Grass’ use to treat wounds, burns and even hypertrophic scarring.

Containing ingredients like Centella Asiatica leaf water, raspberry leaf extract and panthenol, Tiger Grass creams moisturize the face. 

Even if you're skeptical of the Tiger Grass craze, products like Dr. Jart’s Cicapair Tiger Grass moisturizer also contains SPF 30+ sunscreen, which guarantees increased protection from the sun.


This may seem obvious, but sometimes the best life hacks are incredibly basic. In the sunny season, make sure to stay hydrated.   

When it comes to lessening the effects of sun damage on areas susceptible to cold sore outbreaks, the research is still very thin. 

Even so, research that drinking water and staying hydrated may “positively impact normal skin physiology, as expressed by its hydration and biomechanical behavior, and in particular in those individuals with lower daily water consumptions.”

If your skin isn’t hydrated, not only is it more susceptible to damage; it also lengthens healing time in the event you do experience a cold sore outbreak. 

Spend Less Time In The Sun

Though there’s no shortage of articles online warning people about the danger of sunbathing, people are still inexplicably drawn to the allure of being a bronzed god or goddess. 

According to the CDC, skin cancer is the highest form of cancer in the U.S. 

Can you go in the sun with a cold sore? Of course! Does going out in the sun mean you'll absolutely have an outbreak? Absolutely not. 

But be smart about it. Little things like always wearing a hat or other protective clothing, staying in the shade and not sitting in the sun for too long can go a long way in preventing skin irritation or damage.

Why Valtrex Is Your Most Reliable Option?

Regardless if you have been diagnosed with HSV-1 or not, you should be smart about sun protection. While protecting yourself from a severe sunburn and skin irritation can stop a cold sore from being triggered, there are a myriad of different ways in which they can still happen. If you do end up having a cold sore outbreak, you should rely on scientifically verified and tested methods like the antiviral medication Valtrex to stop the infection from multiplying and affecting other places of the body. We swear by the stuff.

If you want to read more about getting a healthier lifestyle, check out our blog.

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.