Topic Overview

What are cold sores?

Cold sores, sometimes called
fever blisters, are groups of small blisters on the lip and around the mouth.
Often the first sign of a cold sore is a spot that tingles, burns, or itches. A blister usually forms within 24 hours. The skin around the blisters is often red, swollen, and sore. The blisters may
break open, leak a clear fluid, and then scab over after a few days. They
usually heal in several days to 2 weeks.

What causes cold sores?

Cold sores are caused by
herpes simplex virus (HSV). There are two types of
herpes simplex virus: HSV-1 and HSV-2. Both virus types can cause sores around the mouth (herpes labialis) and on the genitals (genital herpes).

The herpes simplex virus
usually enters the body through a break in the skin around or inside the mouth.
It is usually spread when a person touches a cold sore or touches infected
fluid-such as from sharing eating utensils or razors, kissing an infected
person, or touching that person’s saliva. A parent who has a cold sore often
spreads the infection to his or her child in this way. A person can spread the virus to someone else a few days before the sore appears until the sore is completely healed. Cold sores can also be
spread to other areas of the body.

What are the symptoms?

The first symptoms of cold
sores may include a spot that tingles, burns, or itches around your mouth and on your lips. You may also have a fever, a sore
throat, or swollen glands in your neck or other parts of the body. Small
children sometimes drool before cold sores appear. After the blisters appear,
the cold sores usually break open, leak a clear fluid, and then crust over and
disappear after several days to 2 weeks. For some people, cold sores can be
very painful.

Some people have the virus but don’t get cold sores.
They have no symptoms.

How are cold sores diagnosed?

Your doctor can tell
if you have cold sores by asking you questions to find out whether you have
come into contact with the virus and by examining you. You probably won’t need
any tests.

How are cold sores treated?

Cold sores will
usually start to heal on their own within a few days. But if they cause pain or
make you feel embarrassed, they can be treated. Treatment may include skin
creams, ointments, or sometimes pills. Treatment may get rid of the cold sores
only 1 to 2 days faster, but it can also help ease painful blisters or other
uncomfortable symptoms.

The herpes simplex virus that causes cold
sores can’t be cured. After you get infected, the virus stays in your body for
the rest of your life. If you get cold sores often, treatment can reduce the
number of cold sores you get and how severe they are.

How can you prevent cold sores?

There are some
things you can do to keep from getting the herpes simplex virus.

  • Avoid coming into contact with infected body fluids, such
    as kissing an infected person.
  • Avoid sharing eating utensils,
    drinking cups, or other items that a person with a cold sore may have

After you have been infected with the virus, there is no
sure way to prevent more cold sores. But there are some things you can do to
reduce your number of outbreaks and prevent spreading the virus.

  • Avoid the things that trigger your cold sores, such as
    stress and colds or the flu.
  • Always use lip balm and sunscreen on
    your face. Too much sunlight can cause cold sores to flare.
  • Avoid
    sharing towels, razors, silverware, toothbrushes, or other objects that a
    person with a cold sore may have used.
  • When you have a cold sore,
    make sure to wash your hands often, and try not to touch your sore. This can
    help keep you from spreading the virus to your eyes or genital area or to other
  • Talk to your
    doctor if you get cold sores often. You may be able to take prescription pills
    to prevent cold sore outbreaks.

Frequently Asked Questions

Learning about cold sores:

Being diagnosed:

Getting treatment:

Living with cold sores:


Cold sores are
blisters on the lips and the edge of the mouth that are caused by an infection
with the
herpes simplex virus (HSV). Often the first sign of a cold sore is a spot that tingles, burns, or itches. A blister usually forms within 24 hours.

Cold sore
blisters usually break open, weep clear fluid, and then crust over and
disappear after a few days.

Other symptoms may include:

  • A sore mouth that makes eating, drinking, and
    sleeping uncomfortable. Cold sores can be painful.
  • A
  • A sore throat.
  • Swollen
    lymph nodes in the neck.
  • Drooling, in
    small children.

You may not develop cold sores when you are first infected
with HSV. If cold sores do develop when you are first infected, they may be
more severe than in later outbreaks. During the first outbreak of cold sores,
the blisters may spread to any part of the mouth.

After you become
infected, HSV remains in your body and may cause cold sores to return
throughout your lifetime (recurrent cold sores).

Recurrent cold sores usually develop where
facial skin and the lip meet. About 6 to 48 hours before a cold sore is
visible, you may feel tingling, burning, itching, numbness, tenderness, or pain
in the affected area. This is called the prodromal stage.

common triggers that cause cold sores to return include:

People who have weakened immune systems are more likely
than those with strong immune systems to have longer or more severe outbreaks
of cold sores. HSV infection may be life-threatening in certain people who have
weak immune systems.

Who is at greatest risk for developing cold sores?

Anyone who is exposed to the herpes simplex virus (HSV) is at risk for
developing cold sores. But many people have the virus and may never develop
cold sores.

People who have weakened immune systems are at an
increased risk for having more severe and longer-lasting outbreaks of cold

One form of HSV infection is seen most often in children 1
to 3 years old. This type of HSV infection (primary herpes stomatitis) can
cause a high fever and blisters throughout the mouth, which can interfere with
the ability to eat. It can be serious in children-they can get quite sick from
this illness, although they usually recover without any long-term problems.

Exams and Tests

Your doctor can diagnose
cold sores by asking questions to find out whether
you’ve been exposed to the
herpes simplex virus (HSV) and by examining you. No
further testing is usually needed.

There are two types of herpes
simplex virus: HSV-1 and HSV-2. Both virus types can cause lip and mouth sores
(herpes labialis) and
genital herpes if your skin comes into contact with
either type.

If it is not clear that you have cold sores,
herpes tests may be done. The doctor takes a sample of
fluid from a sore and has it tested. Having the sample taken is usually not
uncomfortable even if the sore is tender or painful.

Treatment Overview

There is no cure for
cold sores, nor is there a cure for the
herpes simplex virus (HSV) that causes them. Most cold
sores will go away on their own. But medicines may slightly reduce the duration
of cold sores and sometimes prevent a future outbreak.

with medicines depends on whether you are having a first outbreak or a
recurrent outbreak or are trying to prevent future outbreaks.

treating a first outbreak of cold sores,
oral antiviral medicines may reduce pain and slightly improve healing

For treatment of recurrent cold sores, the following
medicines may reduce the severity and duration of the outbreak:footnote 1

  • Topical creams or ointments, which are
    available with or without a prescription, can reduce pain, itching, and healing
  • Oral antiviral medicines, which are available by
    prescription only, may be used when the first symptoms (such as burning or
    itching) begin. These medicines have little effect after the sore

Oral antivirals may also be taken daily to prevent
recurring cold sores, especially in people who have frequent and painful

If you have a
weakened immune system and develop cold sores, you may
need medicines to control your symptoms or daily doses to
prevent outbreaks.

Other treatments

The first episode of cold sores
can be so painful that you may have trouble eating, drinking, and sleeping.
A child who has a fever and many mouth sores may need to be encouraged to drink
water and other fluids to prevent

Adults and older children
who have a painful first episode of cold sores may sometimes need a
prescription-strength medicated mouth rinse to reduce pain.

Complementary medicine

complementary medicine treatments are available if you wish to try an
alternative way to ease your symptoms.

Vitamin C, lysine supplements, and lemon balm are examples of complementary treatments that may provide some
relief during a cold sore outbreak. Vitamin C may be taken as an oral tablet, in a cream that can be put on the cold sore (topical cream), or as liquid vitamin C applied to the cold sore. Lysine supplements are taken as pills, and lemon balm is available in a topical cream.

Zinc oxide topical cream may reduce the duration of an outbreak.footnote 1

Home Treatment

cold sores heal on their own. But you can manage your
symptoms at home by:

  • Placing a cool, wet towel on the sores 3 times
    a day for 20 minutes each time to help reduce redness and
  • Using a mouth rinse that has baking soda to
    soothe a sore mouth.
  • Avoiding foods that contain acid (such as
    citrus fruits and tomatoes).
  • Using nonprescription ointments that
    can relieve pain or help heal the cold sore.

    • Some products such as Abreva and
      Zilactin can speed the healing of cold sores or prevent them if
      applied early enough.
    • Other products such as Orajel and Anbesol can numb sore
      areas in the mouth or on the lips.
    • Children age 2 and older can be treated with Zilactin-L Liquid, Orajel Baby, and Anbesol. Abreva is for people age 12 and older, so talk to your doctor before using it for a younger child. And if your child is younger than 2, talk to your doctor before using any of these medicines.

Ask your doctor if you can take ibuprofen (such as Advil or Motrin) or
acetaminophen (such as Tylenol) to reduce pain. Do not give aspirin to anyone younger than 20 because of its link to
Reye syndrome, a serious but rare problem. Be safe with medicines. Read and follow all instructions on the label

You can reduce the frequency of cold sore outbreaks by
taking the following steps:

  • Avoid prolonged exposure of your lips to
    sunlight. Protect your face from the sun. Using lip balm that contains sunscreen may help reduce outbreaks of cold sores.
  • Avoid intimate
    contact (such as kissing) with people who have cold sores or
    genital herpes.
  • Avoid foods that seem to cause your cold
    sores to recur. Some people find that they have fewer outbreaks if they don’t eat nuts, chocolate, or gelatin.
  • Avoid sharing towels, razors, silverware,
    toothbrushes, or other objects that a person with a cold sore may have

These measures may help prevent the spread of cold sores in

  • Encourage frequent hand-washing.
  • Do
    not let children share toys that other children put in their
  • Clean toys occasionally with a disinfectant.
  • If
    children have open or weeping cold sore blisters, keep them home until the
    blisters begin to scab over.
  • Do not let children kiss each other
    while they have cold sores or uncontrollable drooling.
  • Use disposable gloves
    or a cotton swab to apply medicated ointment to a child’s cold sores.

Other Places To Get Help


American Academy of Dermatology

American Sexual Health Association: Herpes Resource Center

Related Information



  1. Worrall G (2009). Herpes labialis, search date February 2009. Online version of BMJ Clinical Evidence:

Other Works Consulted

  • Wolff K, et al. (2013). Herpes simplex virus disease. In Fitzpatrick’s Color Atlas and Synopsis of Clinical Dermatology, 7th ed., pp. 660-667. New York: McGraw-Hill.
  • Habif TP, et al. (2011). Herpes simplex section of Viral infections. In Skin Disease: Diagnosis and Treatment, 3rd ed., pp. 224-229. Edinburgh: Saunders.
  • Sterling JC (2010). Herpes labialis. In MG Lebwohl et al., eds., Treatment of Skin Disease: Comprehensive Therapeutic Strategies, pp. 303-305. Edinburgh: Saunders Elsevier


ByHealthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD – Internal Medicine
Adam Husney, MD – Family Medicine
Specialist Medical Reviewer Kathleen Romito, MD – Family Medicine

Current as ofMarch 20, 2017