Cold Sores (Fever Blisters): Teen Version

What are cold sores?

Cold sores are small, painful bumps or blisters on the outer lip. They happen only on one side of the mouth and appear in a cluster. Just before a cold sore develops, you may feel a tingling or burning on the outer lip at the same place where you had cold sores before.

What is the cause?

Cold sores are caused by the herpes simplex virus. The sores happen for the first time after you have had contact with someone with herpes. Thereafter, the virus lives in the sensory nerve and can cause cold sores again. About 20% of adults have recurring cold sores. The sores come back because of sunburn, fever, friction, stress, injury during dental procedures, or physical exhaustion.

How long do cold sores last?

The blisters will rupture, scab over, and dry up. The whole process takes 7 to 10 days. The sores do not cause scars. If started early, treatment with antiviral pills can shorten the course by many days.

How can I take care of myself?

  • Ice

    If you feel tingling in the usual place but the blisters are not yet present, apply an ice cube or ice pack continuously for 20 minutes. This may stop the infection from progressing.

  • Cold sores ointment

    Once you get fever blisters, start applying a special cold sore ointment as soon as any small bumps appear. Docosanol (Abreva) is an example of one nonprescription cream. If you don’t have a special ointment, cover the fever blisters with petroleum jelly to reduce the pain. Reapply it 4 times a day.

  • Medicines

    Give acetaminophen or ibuprofen for pain relief. Once you get fever blisters, you usually can’t make them heal faster unless you have antiherpes pills and start them as soon as any small bumps appear. These require a prescription. Antiherpes ointments do not make the sores heal faster.

How can cold sores be prevented?

Since fever blisters are often triggered by exposure to intense sunlight, prevent them in the future by using a lip balm containing sunscreen with an SPF of 30.

Infection is spread through contact with fluid from the blisters. Avoid spreading this germ to another person’s eye, because an eye infection can be serious. Therefore, don’t pick at the sore, and wash your hands frequently. Since the condition is contagious, avoid kissing other people during this time.

If you are going skiing or to the beach and have had frequent herpes flare-ups in the past, despite careful use of sunscreen, call your healthcare provider. Taking prescription antiherpes pills before such outings can prevent most flare-ups.

When should I call my healthcare provider?

Call during office hours if:

  • Any sores occur near the eye.
  • The sores last longer than 2 weeks.
  • You have questions about prescription medicine for herpes.
  • You have other concerns or questions.
Written by Barton D. Schmitt, MD, author of “My Child Is Sick,” American Academy of Pediatrics Books.
Pediatric Advisor 2015.1 published by RelayHealth.
Last modified: 2013-06-03
Last reviewed: 2014-06-10
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright ©1986-2015 Barton D. Schmitt, MD. All rights reserved.

Patient Portal

myTuftsMed is our new online patient portal that provides you with access to your medical information in one place. MyTuftsMed can be accessed online or from your mobile device providing a convenient way to manage your health care needs from wherever you are.

With myTuftsMed, you can:

  1. View your health information including your medications, test results, scheduled appointments, medical bills even if you have multiple doctors in different locations.
  2. Make appointments at your convenience, complete pre-visit forms and medical questionnaires and find care or an emergency room.
  3. Connect with a doctor no matter where you are.
  4. Keep track of your children’s and family members’ medical care, view upcoming appointments, book visits and review test results.
  5. Check in on family members who need extra help, all from your private account.


Your privacy is important to us. Learn more about ourwebsite privacy policy. X