Cold sores are small, painful, fluid-filled blisters that are usually found at the border of the lip. Medications may help relieve symptoms or shorten the length of time you have them.
Cold sores are caused by two types of herpes simplex viruses. In most cases, people contract the virus as young children.
You may get the virus from:
- Contact with the fluid from a cold sore of another person or genital herpes sores
- Contact with the eating utensils, razors, towels or other personal items of a person with active cold sores
- Sharing food or drink with a person with active cold sores
- Contact with the saliva of a person who has the herpes virus even if no sores are present
The first episode of illness with the herpes virus can cause a body-wide illness. After that, the virus lies quietly in the skin until it is reactivated. The reactivated virus causes a cold sore to appear.
Factors that can reactivate the virus and lead to an outbreak of cold sores include:
- Infection, fever, cold or other illness
- Exposure to sun
- Physical or emotional stress
- Certain drugs
- Weakened immune system
- Physical injury or trauma
- Dental or other oral surgery
A cold sore occurs most often on the lips, but can occur in the mouth or other areas of the skin. You may notice some itching, tingling or burning the day before a cold sore appears. The sores will dry up with a crust and become a shallow sore after a few days.
Diagnosis & Treatment
Your doctor will ask about your symptoms, medical history and perform an exam. Your doctor can usually diagnose a cold sore by looking at it. Rarely, your doctor may send a sample of the blister to a lab to be analyzed.
Cold sores usually heal within two weeks even without treatment. However, certain treatments may help decrease your symptoms and shorten the time that you have a sore.
To help reduce pain, consider:
- Nonprescription cold sore creams and ointments
- Placing ice on the blisters
- Rinsing with mouthwash containing lidocaine
Prescription antiviral creams or ointments, may also help decrease pain.
Your doctor may prescribe oral antiviral medications to suppress frequent outbreaks. You should take these the moment you feel a cold sore coming.
Avoid rubbing or scratching blisters as this can delay healing and cause an infection. If you have an active cold sore, avoid touching the infected area. This limits the spread of the virus to other people and/or other parts of your body.
To reduce your chance of catching a virus, take these steps:
- Be careful around people who have active cold sores. Avoid skin contact and kissing. Do not share food, drink or personal items.
- Avoid performing oral sex on a person with genital herpes. The virus spreads more easily when active sores are present.
The herpes virus never leaves your body once you have it. There is no cure for the infection. If you already have a herpes infection, to prevent future outbreaks of cold sores or blisters:
- Avoid long periods of time in the sun
- Use sunblock on lips and face when in the sun
- Get adequate rest and relaxation, and try to minimize stress
- Talk to your doctor about antiviral medicines if you have outbreaks often
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Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.