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Cold sores

  • Cold sores, also called oral herpes or fever blisters, are small blisters around the mouth (including lips, chin, and cheeks) or in the nostrils. Episodes of the cold sores usually last no longer than two weeks. They are contagious.

    • More than half of people living in the United States have been infected by the time they reach their 20s.
    • There’s no cure; treatment only helps with symptoms.
    • Cold sores are contagious whether or not symptoms are present.
    • They are transmitted through direct contact with an infected person’s contagious area.

    How Children’s Hospital Boston approaches cold sores

    Children’s has created two Web sites directly aimed at young women and young men to discuss conditions that they may be exposed to cold sores. The mission of these sites (youngwomenshealth.org and youngmenshealthsite.org) is to help teens, their parents, teachers and health care providers improve their understanding of normal health and development, as well as of specific diseases and conditions.

    Boston Children's Hospital
    300 Longwood Avenue
    Boston MA 02115

     617-355-7701
     fax: 617-730-0505


  • What are cold sores?

    Cold sores, also called oral herpes or fever blisters, are small blisters around the mouth (including lips, chin, and cheeks) or in the nostrils. Episodes of the cold sores usually last no longer than two weeks. They are contagious.

    What causes cold sores?

    Cold sores are caused by the herpes simplex virus. The most common strain of the virus is herpes simplex virus 1. The herpes simplex virus is not curable, but may lay dormant for long periods of time. Hot sun, cold wind, a cold, or a depressed immune system can cause an outbreak of herpes simplex virus symptoms. Oral herpes is transmitted through:

    • direct contact between the contagious area and broken skin (a cut or break) and mucous membrane tissue (such as the mouth or genitals)
    • contagious whether or not symptoms are present

    Are cold sores common?

    Type 1 herpes virus infects more than half of the people in the United States by the time they reach their 20s.

    What are the symptoms of cold sores?

    Some children and adults never experience any symptoms with the first attack; others have severe flu-like symptoms and ulcers in and around the mouth. While symptoms may vary child-to-child, they may include:

    • tingling of the lips
    • a small blister or cluster of blisters on the lips and mouth that enlarge, burst, then crust over
    • itching and irritation of the lips and mouth
    • soreness of the lips and mouth that may last from three to seven days
  • How does a doctor know that it’s cold sores?

    Your doctor can diagnose oral herpes by looking at the sores during a physical exam and by testing fluid taken from the sores to see if you have HSV-1 or HSV-2.

  • Although cold sores cannot be cured, treatment may help alleviate some symptoms, if severe.

    Treatment may include prescription medications including:

    • idoxuridine paint
    • antiviral medication
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