Person with a cold sore.

Summer Sun May Trigger Cold Sores: Here’s What to Do

The ultraviolet rays of the sun can reactivate the herpes simplex virus 1 that causes cold sores. If you’re susceptible to cold sores, you might want to use antiviral drugs to minimize the number of acute outbreaks you experience.

Long gone are the days when summer ushered in a carefree season for soaking up the sun and relaxing. These days, heightened awareness of the damage the sun can cause prompts most folks to be much more cautious about their time in the sun.

And sun damage isn’t limited to the threat of skin cancer and premature aging of the skin. Too much time in the sun can also trigger outbreaks of cold sores, caused by the herpes simplex virus 1, which is present in roughly half of all Americans, according to the Centers for Disease Control and Prevention.

No Cure for Herpes Simplex Viruses

There is at present no way to permanently rid your body of any herpes simplex virus. Once contracted, both herpes simplex virus 1 and herpes simplex 2, the latter of which causes genital herpes, take up permanent residence in your body. The viruses can lie dormant for lengthy periods of time but once reactivated can cause fresh outbreaks.

A paper published online at in November 2018 explores the relationship between sunlight and the herpes virus. The study explains that it’s the ultraviolet components (UVA and UVB) of the sun’s radiation that are responsible for reactivation of the herpes virus.

It’s Difficult to Avoid the Sun

While the best protection against solar reactivation of the herpes virus is avoidance of exposure to the sun’s harmful ultraviolet rays, that is difficult to accomplish. And for some people infected by the herpes virus, staying out of the sun is not only impractical but impossible.

If you know you’re susceptible to cold sores and have suffered from them in the past, you can help to guard against a new outbreak by applying plenty of sunblock and keeping your lips moisturized during the summer months. However, even that may not be enough for those who are highly susceptible to the reactivation of the virus by sun exposure.

Antivirals Can Help

In such cases, the wisest course of action is the use of antiviral medications, which won’t cure you of the virus but can suppress it so that you’re likely to experience fewer acute outbreaks. These medications can also help to speed recovery from an acute outbreak, which in the case of cold sores usually show up as fluid-filled blisters on or around the lips.

Among the antivirals most highly recommended for the suppression of herpes simplex virus 1 and 2 and the treatment of acute outbreaks are acyclovir and valacyclovir. The former is also available under the brand names Sitavig and Zovirax, while the latter is also sold under the brand name Valtrex.

How the Antivirals Work

Most commonly used in oral form, these medications keep the herpes simplex viruses from multiplying, which helps to reduce the number of acute outbreaks of cold sores or genital herpes lesions.

Both acyclovir and valacyclovir are effective in suppressing outbreaks of both cold sores and genital herpes. Both are available in generic form as well as in the brand-name formulations mentioned earlier. Both have similar side effects, which generally speaking are mild and tend to disappear upon continued use. Such adverse effects include fatigue, headache, nausea, and diarrhea/vomiting.

                                                                                * * *

If your doctor feels that an antiviral medication might help you to minimize acute outbreaks of cold sores, you should consider ordering those drugs online from This longtime online facilitator carries both acyclovir and valacyclovir, as well as Valtrex, a brand-name formulation of valacyclovir. If you have a prescription from your doctor, you can fax it or scan and email it along with your order.

Alternatively, eDrugstore can set up a complimentary online consultation with a licensed U.S. physician who can authorize a prescription if appropriate. To learn more, visit eDrugstore’s Sexual Health page.

Don Amerman has spent more than three decades in the business of writing and editing. During the last 15 years, his focus has been on freelance writing. For almost all of his writing, He has done all of his own research, both online and off, including telephone and face-to-face interviews where possible. Don Amerman on Google+