After being exposed to the herpes simplex 1 virus for the first time, you may develop a blistering rash in the mouth that may be accompanied by a body-wide, flu-like illness. This first outbreak of cold sores is usually gone within 7-10 days, but can last up to 20 days.


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The symptoms of the first outbreak are:

  • A blistering, painful rash of small ulcerations across the lips, gums, tongue, and the inside of the mouth (more common in children)
  • Pain and blistering on the soft roof of the mouth, tonsils, and throat (more common in adults)
  • Flu-like symptoms:
    • Swollen, ]]>sore throat]]>
    • Mouth sores
    • Fever
    • Decreased energy
    • Muscle aches and pains
    • Difficulty breathing
    • Swollen glands (lymph nodes) in the neck

After these initial symptoms, the virus may lie quietly in the nerves until it is reactivated, typically by stress or illness. Direct sunlight, a weakened immune system, and menstruation can also trigger reactivation. If reactivated, the virus will come out as a cold sore (fever blister). A few days before, you may notice some itching, burning, or pain in the area where the cold sore will appear. Some people have outbreaks regularly, and some never have another after the initial infection.

The symptoms of an active cold sore are:

  • Small, painful, fluid-filled, red-rimmed blisters
  • After a few days, the blisters dry and form a scab
  • Scabs heal in about five days, usually without scarring or loss of sensation