What Is a Cold Sore?
A cold sore is a group of tiny, painful blisters caused by the herpes simplex virus (HSV). They’re also called fever blisters or herpes simplex labialis.
Up to 90% of people around the world have at least one form of HSV.
Your symptoms are usually the most serious the first you time you get cold sores. A first-time cold sore can make a child seriously ill.
After the first outbreak, your body should make antibodies, and you may never have another infection. But many people get cold sores that come back.
Cold Sore Symptoms
Cold sores are most likely to show up on the outside of your mouth, lips, and buttocks, but you can also get them on your nose and cheeks.
You may get cold sores as late as 20 days after you’re infected. The sore might appear near where the virus entered your body.
You might also have red or swollen gums, swollen glands in your neck, a fever, or muscle aches.
Cold Sore Causes
You catch HSV when you come into contact with people or things that carry the virus. For instance, you can get it from kissing someone who has the virus or from sharing eating utensils, towels, or razors.
Two types of the virus can cause cold sores: HSV-1 and HSV-2. Both types can also cause sores on your genitals and can be spread by oral sex.
Type 1 usually causes cold sores, and type 2 mostly causes genital herpes, but either can be found in both areas.
Certain things can trigger an outbreak, including:
- Some foods
- Stress
- Fever
- Colds
- Allergies
- Fatigue
- Sunburn or being in strong sunlight
- Dental work or cosmetic surgery
- Your period
Cold Sore Risk Factors
Cold sores generally aren’t serious, but the infection may be life-threatening if you have a weakened immune system because of AIDS, another condition, or medications.
If you have a serious case of the skin condition eczema, you may get cold sores over large parts of your body.
Cold Sore Diagnosis
Your doctor might diagnose a cold sore just by looking at the blisters. They can also swab the blister and test the fluid for HSV.
Cold Sore Treatment
There’s no cure for cold sores. Once you have the virus, it stays in your body. The sores themselves usually heal on their own in one to two weeks.
Antiviral medications can speed healing, especially if you take them at the first sign of an outbreak. Your doctor might tell you to use:
Cream that you apply on the sores. Acyclovir (Zovirax) and penciclovir (Denavir) require a prescription, or you can get docosanol (Abreva) over the counter.
Pills you swallow. You need a prescription to get medicines like acyclovir (Sitavig, Zovirax), famciclovir (Famvir), or valacyclovir (Valtrex).
Medicine injected into your bloodstream (called intravenous or IV). Foscarnet (Foscavir) is an injection for a serious cold sore case and acyclovir can also be injected.
Cold Sore Complications
Complications from a cold sore are rare, but they can happen if the virus spreads to another part of your body.
Cold Sore Prevention
To lower your risk of another outbreak:
- Get plenty of rest. A lack of sleep weakens your immune system, so you get sick more easily.
- Wear lip balm with sunscreen. Look for SPF on the label.
- Talk with your doctor. If you get sores often, they might have you take antiviral medicine every day.
Keep in mind that you can spread the virus even if you don't have symptoms.
Show Sources
Photo Credit: Science Photo Library/Getty Images
SOURCES:
Columbia University College of Dental Medicine: "Cold Sores and Fever Blisters."
Academy of General Dentistry: "What Are Cold Sores?"
MedlinePlus: "Herpes – oral."
American Academy of Dermatology: "Cold Sores."
Cleveland Clinic: "Cold Sores."
Nemours/TeensHealth: "Cold Sores (HSV-1)."
National Library of Medicine: "Zovirax."
Mayo Clinic: "Penciclovir (Topical Route)," "Acyclovir (Oral Route, Intravenous Route)," "Famciclovir (Oral Route)," "Valacyclovir (Oral Route)," "Cold Sore."
British Association of Dermatologists: "Eczema Herpeticum."
Arvin, A., Campadelli-Fiume, G., Mocarski, E., et al., editors. Human Herpesviruses: Biology, Therapy, and Immunoprophylaxis, Cambridge University Press, 2007.
