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Cold sores, sometimes called
fever blisters, are groups of small blisters on the lip and around the mouth.
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.
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. Cold sores can also be
spread to other areas of the body.
The first symptoms of cold
sores may include pain around your mouth and on your lips, 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
Some people have the virus but don't get cold sores.
They have no symptoms.
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
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
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.
There are some
things you can do to keep from getting the herpes simplex virus.
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.
Learning about cold sores:
Living with cold sores:
Cold sores are
blisters on the lips and the edge of the mouth that are caused by an infection
herpes simplex virus (HSV).
blisters usually break open, weep clear fluid, and then crust over and
disappear after a few days.
Other symptoms may include:
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.
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
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.
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
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.
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
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 higher doses of these medicines to control your symptoms or daily doses to
Although it is rare, children and adults with
weakened immune systems may also need to take
antibiotics during severe episodes of cold sores to
bacterial infections that may develop.
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 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
cold sores heal on their own. But you can manage your
symptoms at home by:
You can reduce the frequency of cold sore outbreaks by
taking the following steps:
These measures may help prevent the spread of cold sores in
Worrall G (2009). Herpes labialis, search date February 2009. Online version of BMJ Clinical Evidence: http://www.clinicalevidence.com.
Other Works Consulted
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
Wolff K, Johnson RA (2009). Herpes simplex
virus (HSV) infection. In Fitzpatrick's Color Atlas and Synopsis of Clinical Dermatology, 6th ed., pp. 813–826. New York:
ByHealthwise StaffPrimary Medical ReviewerE. Gregory Thompson, MD - Internal MedicineSpecialist Medical ReviewerThomas M. Bailey, MD - Family Medicine
Current as ofJune 4, 2014
Current as of:
June 4, 2014
E. Gregory Thompson, MD - Internal Medicine & Thomas M. Bailey, MD - Family Medicine
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