Medical Review By: Camila Yepes, PA-C
Cold sores, aka fever blisters, are caused by the herpes simplex virus (HSV) — not by colds or fevers. But like colds, they are very contagious. You can spread HSV at any point from the first warning tingle up until the cold sore scab has completely disappeared. It’s even theoretically possible to spread the virus when you don’t have a cold sore.
Read on to learn more about cold sores and how to stop the spread.
What causes cold sores?
Oral herpes infections are spread from person to person, usually through direct contact — for example, through kissing or oral sex. They can also be spread by sharing personal items such as drinking glasses or lip balm.
Of course, you can develop a cold sore without coming into contact with someone who has one. That’s because most adults have already been infected with HSV, typically during childhood, and the virus remains in the body, hiding in nerve cells, for life.
Certain triggers can “wake up” the virus, resulting in a cold sore. These include sun exposure, cold wind, cracked lips, hormonal changes during menstruation or pregnancy, emotional stress, surgery, and anything that taxes your immune system, such as the common cold or another illness.
Cold sore stages
Stage 1: You’ll feel tingling, itching, or burning somewhere around your mouth or at the base of your nose. You’re already contagious at this stage (called the prodome stage). This is the time to apply an over-the-counter product such as Abreva or take an oral antiviral medication such as valacyclovir if your doctor has prescribed one. Valacyclovir is highly effective at shortening outbreaks when taken within the first 24 hours of symptoms.
Stage 2: After a day or two of tingling, blisters filled with clear liquid develop and the skin under and around them reddens. Cold sores spread easily at this stage. Do not break the blisters.
Stage 3: A few days later, usually on day four, the blisters break on their own, creating an open sore. This stage, which doctors call the ulcer or weeping stage, is when a cold sore is the most contagious.
Stage 4: The sore starts to dry out and scab over. It may crack or bleed. The sore is still contagious.
Stage 5: The sore begins to scab over. When the scab falls off, the area may look pink or red for a few days. The sore is no longer contagious once the skin heals.
Stopping the spread
Cold sores can spread through saliva and through skin-to-skin contact. To avoid infecting other people, follow these tips during every stage of a cold sore.
Avoid touching the area. If you must scratch when it itches, wash your hands thoroughly afterward. Apply any topical treatments with a cotton swab, not your finger. Don’t pick at the scab (this will only prolong the healing process).
Don’t share any personal items. This includes food, drinks, eating utensils, straws, toothbrushes, razors, lip balm, petroleum jelly and any cold sore cream or ointment you use.
Don’t kiss anyone or nuzzle your baby. Kissing your baby while you have a cold sore is dangerous because the virus is far more severe in infants, who don’t have a fully developed immune system. You should also avoid close contact with anyone who has a weakened immune system, and anyone who has eczema. People with eczema are at risk of a potentially serious skin infection called eczema herpeticum.
Refrain from oral sex. Genital herpes is typically caused by a different strain of HSV (HSV-2), but it is possible for your partner to develop “oral herpes” (HSV-1) on their genitals from exposure to a cold sore on your mouth.
The best way to avoid spreading cold sores is to avoid getting them in the first place. While you have limited control over some common triggers, you can lower your risk of outbreaks caused by sun exposure by wearing lip balm with an SPF of at least 30.
If you get cold sores several times a year, ask your dermatologist about a prescription for an antiviral medicine to take at the first sign of an outbreak. People who get cold sores many times a year may be prescribed a low-dose antiviral medication to take daily in order to help prevent outbreaks. Taking supplements of the amino acid lysine coupled with avoiding foods high in the amino acid arginine (notably, nuts and seeds) may help, too.
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Article Written By: Jessica Brown, a health and science writer/editor based in Brooklyn, New York. She has written for Prevention magazine, jnj.com, BCRF.org and many other outlets.
