Springdale Mason Pediatrics

Cold Sores (Fever Blisters)


  • Sores on the outer lip caused by the herpes virus
  • Sores tend to recur

Call or Return If

  • Sores occur near or in the eye
  • Sores last over 2 weeks
  • You think your child needs to be seen
  • Your child becomes worse

About This Topic


  • A cluster of painful, small bumps or blisters on the outer lip
  • The small blisters often rupture and form 1 big sore (cold sore)
  • Present only on one side of the lip. It doesn't cross the midline.
  • Cold sores are a problem that recurs (called flare-ups). They recur in the same place each time.
  • An early sign of a sore is tingling or burning on the outer lip.


  • Cold sores are caused by the herpes simplex virus type 1. It is passed to another after contact with someone with an open lip sore.
  • Once infected, the virus stays in the body. It can cause cold sores to recur.
  • The sores come back because of different triggers. Some are sunburn, fever, colds, lip friction, lip injury, menstrual periods and stress. Cold sores usually start 2 to 3 days later.

Prevention of Spread to Others

  • Herpes from fever blisters can spread to others.
  • Help your child not to pick or rub the sore. Don't open the blisters. Wash the hands often.
  • Since the blisters are contagious, avoid kissing other people during this time. Avoid sharing drinking glasses or eating utensils.
  • If your child is young and puts everything in the mouth, avoid sharing toys. Do this for a week.
  • Avoid contact with anyone who has eczema or a weakened immune system.
  • Teens. Avoid oral sex during this time. Herpes from sores on the mouth can spread to partner's genital area.
  • The person with cold sores cannot infect himself at other sites. Reason: Immunity protects the rest of the body.

After Care Advice

  • Fever blisters or cold sores occur on one side of the outer lip.
  • They are a problem that recurs in 20% of normal adults. They are less common in children.
  • Cold sores can't hurt the person who has them. But, the virus can spread to others.
  • Cold sores are mainly a cosmetic problem.
  • You can treat cold sores at home.
  • Here is some care advice that should help.
  • Use ice wrapped in wet cloth to the lip for 20 minutes.
  • Follow this with a wet tea bag (tannic acid) to the lip. Put this on for 10 minutes.
  • Do this once.
  • This home treatment may reduce the severity of the infection. You must start early before blisters are seen. This is usually when the lip is tingling or puffy.
Lip Ointment:
  • Apply a fever blister ointment 4 times per day. No prescription is needed. Ask your pharmacist to suggest one.
  • This also must be started as soon as any tingling or small bumps appear.
  • Until purchased, cover the fever blisters with a thin layer of petroleum jelly. This will help to reduce the pain.
Anti-Viral Medicine by Mouth:
  • Oral antiviral drugs may be helpful if started early. But, this is not standard practice. Reason: Fever blisters will go away on their own.
  • If your doctor has prescribed an anti-viral drug, take it as advised.
  • Try to start it when any small bumps appear and before they blister.
  • For pain relief, give acetaminophen every 4 hours OR ibuprofen every 6 hours. Give as needed.
Prevention of Flare-ups of Cold Sores:
  • Fever blisters are often triggered by sun.
  • Use a lip balm with a sunscreen of 30 before being in the sun.
What to Expect:
  • The blisters will break open, scab over, and dry up. This takes 7 - 10 days.
  • After the sores are dry, your child is not contagious.
  • The sores do not leave scars.
  • Cold sores often recur 2 to 3 times per year. Flare-ups can last a lifetime.
Return to School:
  • Older children who have had cold sores before can go to school.
  • Young children with lots of sores may need to be kept home. Keep home until all sores are dry. If puts objects in mouth, avoid sharing toys for one week.

Author: Barton Schmitt MD, FAAP
Copyright 2000-2021 Schmitt Pediatric Guidelines LLC
Disclaimer: This health information is for educational purposes only. You the reader assume full responsibility for how you choose to use it.
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