Cold Sore

This is a viral infection that causes blister-like sores, most commonly on the outer edge of the lip. They are also called fever blisters.

This is a viral infection that causes blister-like sores, most commonly on the outer edge of the lip. They are also called fever blisters.

Cold sores, also known as fever blisters, are blister-like sores that typically develop on the outer edge of the lip. (They can also occur in the mouth.) The sores are caused by one of the herpes simplex viruses, which most people were infected with at some point in their childhood. After the initial infection, the virus remains inactive in some of the nerves on the face. Periodically, the virus may become active again and cause cold sores to redevelop. It is not known what triggers the virus to become active again. Some of the potential reasons include:

  • Stress
  • Hormonal changes (such as menstruation)
  • Exposure to the sun
  • Having a fever

Cold sores are most commonly caused by the herpes simplex virus type 1 (HSV-1). They can also be caused by the herpes simplex virus type 2 (HSV-2), the virus that causes genital herpes. They are contagious from the time the sores develop until they are crusted over. People often have symptoms before the cold sores develop. Some of these symptoms include

  • Tingling of the lips and surrounding area
  • Itching
  • Burning
  • Sore throat
  • Fever
  • Swollen glands
  • Difficulty swallowing can also be present.

Cold sores usually last 1 to 2 weeks and can be spread by sharing personal hygiene products or having close personal contact with an infected person. They can go away without treatment, but there are antiviral medications that can decrease the pain and help shorten the time you are ill. Some other medications that may be recommended include over-the-counter pain medications and anti-viral ointments.

Some things you can do at home to help control the symptoms associated with cold sores include:

  • Use ice or a warm, moist cloth on the blisters
  • Keep the blisters on your lip clean using soap and water
  • Avoid drinking hot liquids or eating spicy, salty or citrus foods
  • Rinse your mouth with salt water or cool water
  • Eat freeze-pops or popsicles.

To prevent reoccurrences, or decrease the spreading of the virus, you can:

  • Keep your lips moist and protect them from the sun with a lip balm or sunscreen.
  • Avoid direct contact with anyone who has cold sores.
  • Do not share personal care items (lipstick, toothbrush).
  • Wash all contaminated items (utensils, towels, linens) in boiling water.
  • Avoid intimate contact if you, or your partner, have a cold sore or other symptoms of a herpes infection.

In general, people with a cold sore should avoid contact with anyone in a high-risk group. This includes:

  • Infants
  • People with reddened or irritated skin (e.g., someone with eczema)
  • People with a weakened immune system due to medication or illness

If you contact your healthcare provider for evaluation of your cold sores, be prepared to discuss your symptoms, how long you've had them and if you have had them before.

  • Before your appointment, make a list of your medical history, including past illnesses, surgeries and hospitalizations. Include a list of your medications (including over-the-counter) and any questions or concerns you want to discuss.
  • During your appointment, ask about your overall health, what symptoms you might have and when you may start to see improvement. Make sure you know what the follow-up plans are, if any, and what symptoms you should report before your next appointment.
  • After your appointment, you should know your diagnosis, understand your treatment plan (including possible alternatives), and what medications are recommended (including possible side effects or precautions).
  • If your healthcare provider wants you to take a medication, ask if an over-the-counter product is right for you.
  • If your healthcare provider prescribes a medication for you, ask for a generic version. If your doctor thinks that a generic version is not right for you, ask for a medication on the lowest available tier of your Prescription Drug List (PDL).

What should I ask my healthcare provider about my cold sores?

  • Are my cold sores contagious?
  • How can I prevent recurrences?
  • Do I need prescription medication?


Also known as:

Oral Sore
Oral Herpes
Fever Blister
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