A cold sore (also called fever blister) is a common viral infection around the lips or inside the mouth. It's caused by the herpes simplex virus. It spreads easily from person to person. People are often first exposed to the virus in childhood. But not everyone who has the virus will develop a cold sore.
A cold sore starts as one or more painful blisters on the lip or inside the mouth. The blisters break open and crust. They usually go away within 1 week. When your child has their first cold sore, they may also have a fever and mouth and throat pain. After the cold sore goes away, it can come back on the same spot. This is because the virus stays in the body. After the first "outbreak," though, other symptoms, such as fever, are usually mild or don't come back.
The frequency of cold sores varies with each child. Some will never have another one. Others will have several each year. Some things that can set off a cold sore to come back include:
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Emotional stress.
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Another illness (cold, flu, or fever).
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Heavy sun exposure.
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Overexertion and fatigue.
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Menstruation.
Cold sores can be spread to other people. A child can start spreading the virus from the cold sore a few days before the sore appears. The sore remains contagious until it is gone.
Home care
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If your child has been prescribed medicines, give these as the health care provider directs. You may use over-the-counter medicine as directed based on age and weight for fever or discomfort. Aspirin should never be used in anyone younger than age 18 who is ill with a fever. It may cause severe disease or death. If your child has chronic liver or kidney disease or ever had a stomach ulcer or gastrointestinal bleeding, talk with your child's provider before using these medicines.
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Applying petroleum jelly to a sore with a disposable cotton-tipped swab may help ease pain. Ask your child's provider before using any other creams or ointments.
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For severe pain, wrap an ice cube in a cloth and have your child apply it to the sore for a few minutes at a time. Older children may rinse their mouth with a glass of warm water mixed with a teaspoon of baking soda to relieve pain.
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Don't give your child acidic foods (citrus fruits and tomatoes).
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Teach your child not to touch the cold sore. The virus can cause a sore on the finger. It's especially important that the child doesn't touch the sore then touch their eyes. The virus can spread to the eyes.
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When your child has a cold sore, make sure your child:
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Washes their hands often.
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Doesn't kiss others.
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Doesn't share drinking cups, utensils, towels, or toothbrushes.
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Clean your child's toys with a disinfectant.
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Have your child wear a hat and use sunblock on their lips before going out in the sun.
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Children with open draining lip sores should stay out of school or child care until the sore forms a scab.
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Teach all family members correct handwashing. They should wet their hands with clean, running water and lather all areas of the hands including the backs of their hands, between their fingers, and under their nails. They should scrub their hands for at least 20 seconds. If they need a timer, they can try humming the “Happy Birthday” song from beginning to end twice. Rinse hands well and dry using a clean towel.
Follow-up care
Follow up with the child's health care provider as advised by our staff.
When to get medical advice
Contact your child's health care provider right away if:
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Your child has eye pain or redness, or drainage from the eye.
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Your child is unable to eat or drink due to pain.
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Your child has a headache.
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Your child's cough increases.
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Symptoms get worse or new symptoms occur.
Call 911
Rarely, the virus can spread to other parts of the body, such as the lungs or the brain.
Call 911 if any of the following occur:
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Unusual irritability
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Drowsiness
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Confusion
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Stiff neck
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Seizure
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Trouble breathing
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