Cold Sores

A cold sore is a blister that typically appears on your lip or around your mouth. The herpes simplex virus type 1 (HSV-1) causes most cold sores. HSV-1 is very contagious. You can prevent getting cold sores by avoiding kissing people with them or sharing objects with them. Cold sores usually go away on their own within a couple of weeks.


A cold sore (oral herpes) is a fluid-filled blister (or a cluster of blisters) that usually appears on your lip or around your mouth.
A cold sore on the mouth of a child.

What is a cold sore?

A cold sore is a fluid-filled blister (or a cluster of blisters) that usually appears on your lip or around your mouth. They can also affect your cheeks, nose and chin. The herpes simplex virus type 1 (HSV-1) causes most cold sores.

Are cold sores herpes?

Other names for cold sores include oral herpes, fever blisters and herpes simplex labialis. Even though people use the name oral herpes — and HSV-1 can spread to your genitals — HSV-1 isn’t the same as HSV-2. HSV-2 is the sexually transmitted virus that causes most cases of genital herpes.

How often do people get cold sores?

A cold sore can develop multiple times a year or only once or twice in your lifetime. The frequency of an outbreak varies from person to person.

Who do cold sores affect?

The virus that causes cold sores can infect people of all ages. Exposure to the virus typically occurs during childhood. Many people catch HSV-1 by the time they turn 5 years old.

It’s possible to develop a cold sore at any age, though the chance of having any outbreak decreases after the age of 35.

How common are cold sores?

Cold sores are widespread. HSV-1 infects more than half of Americans between the ages of 14 and 49. However, many people never develop the sores or have any symptoms. About 20% to 40% of people who have the virus develop the sores.

Cold sore vs. canker sore

Cold sores inside your mouth aren’t cold sores at all — they’re canker sores (mouth ulcers). Cold sores and canker sores look and feel similar, although canker sores can be quite painful. They’re both small, round sores that develop near your mouth. But canker sores only develop inside your mouth, including:

  • On your gums.
  • Inside your cheeks and lips.
  • Under your tongue.
  • On the back of your throat.

Canker sores have a variety of causes. But unlike cold sores, they don’t occur due to a virus, and they aren’t contagious. Causes of canker sores may include:


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Symptoms and Causes

What does a cold sore look like?

Cold sores first look like small blisters that form around your lips and mouth. A cold sore on your lip usually only affects one side of your mouth. They can also show up on your cheeks, nose and chin. After two to three days, the blisters often start to ooze and then form a crust. Healing typically occurs within one to two weeks.

What happens the first time you get a cold sore?

For many people, cold sore symptoms are more severe the first time they have an outbreak. You may experience the following cold sore stages:

  1. The first sign is often a tingling, burning or itching sensation on or around your lips. This cold sore early stage begins about 12 to 24 hours before the sore develops.
  2. The area becomes red, swollen and painful as the blisters form.
  3. Over the next two to three days, the blisters rupture and ooze a clear or slightly yellow fluid. This is sometimes called the “weeping phase.”
  4. About four to five days after the cold sore appears, it crusts and scabs over. It might crack or bleed as it heals.
  5. The scab then falls off, revealing skin that may be a little more pink or reddish than usual for a few days. It usually takes one to two weeks for the sore to heal completely.

What causes cold sores?

Cold sores are sometimes called oral herpes because the herpes simplex virus type 1 (HSV-1) causes them. This virus is very common and highly contagious. It spreads through saliva or close contact — often through kissing or by sharing utensils, straws, towels or lip balm with someone who has a cold sore.

You may not know HSV-1 has infected you because the symptoms of exposure to HSV-1 are generally mild. After initial exposure to HSV-1, children sometimes develop a fever and small blisters inside and around their mouths.

How do you get cold sores?

After HSV-1 has infected you, the virus never goes away. It remains inactive (dormant) in a group of nerve cells in your face called the trigeminal ganglion. Because it can be dormant, some people aren’t aware they have the virus for months or even years after exposure.

When something triggers — or activates — the virus, it “wakes up” and travels through your nerves to your lips, where a cold sore develops. After an outbreak, the virus goes back to sleep in your body.

What triggers a cold sore in one person might not cause an outbreak in another person. Some people with HSV-1 never develop sores.

A variety of factors can activate a cold sore, including:

  • Hormonal changes during menstruation or pregnancy.
  • Sunburn.
  • Extreme temperatures (hot or cold).
  • Stress (physical or emotional).
  • Fatigue.
  • Fever and illness, such as cold or flu.
  • Damaged, dry or cracked lips.

Are cold sores contagious?

Yes, cold sores are highly contagious. They can spread easily from person to person through saliva or direct contact with a person who has one.

How long are cold sores contagious?

In healthy people, cold sores generally clear up on their own in one to two weeks. You’re contagious until all of the sores have scabbed over.


What are the complications of cold sores?

Although complications from cold sores are rare, they can include:

  • Eye infections: The herpes simplex virus (HSV-1) can spread to your eye when you touch a cold sore and then touch your eye. If HSV-1 spreads to your eye, it can cause HSV keratitis, a potentially serious infection of your cornea. Severe HSV keratitis infections can lead to blindness.
  • Genital sores: HSV-1 can spread to your genitals through oral sex. This can produce warts or ulcers on your genitals or anus. However, HSV-1 isn’t the same virus that causes most cases of genital herpes. That’s HSV-2.

For certain groups of people, cold sores can lead to serious complications. The following groups of people should receive medical treatment immediately if they have a cold sore:

  • Newborns: Babies younger than 6 months old may develop complications such as high fever and seizures because their immune systems aren’t fully developed yet.
  • People with compromised immune systems: For people with weakened immune systems, the herpes simplex virus can lead to encephalitis (swelling of the brain). If you have HIV or are receiving chemotherapy treatment, sores could be more severe and could take longer to go away.
  • People with eczema: The herpes simplex virus can cause a life-threatening infection called eczema herpeticum in adults and children with eczema. It’s important to see your healthcare provider right away if you have eczema and you develop a cold sore.

Diagnosis and Tests

How is a cold sore diagnosed?

Your healthcare provider will probably be able to tell if you have a cold sore by looking at the affected area. They may also swab the sore to test the fluid for the herpes simplex virus.

How do I know if I have a cold sore?

If you’ve had one before, you’ll likely recognize the symptoms: a tingling sensation followed by redness, swelling and blisters on or around your lips. You can visit your provider for a diagnosis, although it’s not always necessary.


Management and Treatment

How to get rid of cold sores

You can’t cure oral herpes. The goal of treatment is to heal the outbreak, but it can’t cure the virus. Once you have it, you have it for life.

Although it may take a while to get rid of a cold sore, some medicines can shorten the healing time and make the symptoms less painful. Cold sore treatment may include:

  • Over-the-counter (OTC) medications: You can buy cold sore medicine without a prescription. These are creams or ointments that you apply directly to the sore. If you start using these creams when you first notice tingling or itching — before the cold sore forms — you may be able to prevent it from appearing.
  • Oral antiviral medicine: To treat cold sores, your provider may prescribe an antiviral medication that you take by mouth (orally).
  • Intravenous (IV) antiviral medicine: If other medications aren’t working, your provider may need to prescribe an antiviral medication that they’ll give to you through an IV. In this case, your provider will monitor you closely throughout treatment.


How can you prevent cold sores?

To avoid getting HSV-1, you should take the following precautions around people who have cold sores:

  • Avoid kissing, intimate contact and oral sex with someone who has a sore.
  • Don’t share towels, razors, dishes, cutlery, straws, lip balm or lipstick.
  • Wash your hands before touching your lips, eyes or genitals.

If you’ve already come into contact with HSV-1, take the following steps to reduce your risk of a cold sore outbreak:

  • Try to stay healthy: A fever can trigger a cold sore, which is why people sometimes call them fever blisters.
  • Get enough rest: Fatigue weakens your immune system and makes you more likely to get sick.
  • Wear lip balm with SPF: Protecting your lips from sunburn can help you avoid an outbreak.

If you have a cold sore, be careful around babies. Always wash your hands, and don’t kiss a baby until the sore has healed completely.

Outlook / Prognosis

What’s the outlook for people who have cold sores?

The majority of people who develop cold sores learn to live with and manage their outbreaks. They typically clear up quickly and have no lasting effects. However, in certain groups of people, cold sores can cause life-threatening infections. Newborns, people with eczema and people with compromised immune systems should see a provider right away.

How long do cold sores last?

In healthy people, cold sores usually clear up in one to two weeks.

Living With

What can I do to help relieve the symptoms of cold sores?

While cold sores are uncomfortable, you can find relief at home. Suggestions to help manage them include:

  • Use over-the-counter creams and ointments: Wondering how to get rid of cold sores fast? Creams and ointments can shorten the healing time and ease your symptoms. They’re most effective when you use them as soon as you feel a sore coming on.
  • Take pain relievers: If you’re in a lot of pain, your provider may recommend an over-the-counter topical pain reliever such as lidocaine that you can apply directly to the sore. You can also take acetaminophen or ibuprofen by mouth to ease your discomfort.
  • Wear sunscreen and SPF lip balm: It’s important to make sure a sore doesn’t get sunburned while it’s healing. Also, wearing a lip balm with SPF 30 every day could prevent future cold sores.
  • Avoid acidic foods: Orange juice, tomatoes and other acidic foods can aggravate a sore.
  • Apply a cool compress: You can use a cool, damp washcloth to soothe a cold sore. Apply it for a few minutes off and on throughout the day. Be sure to wash the towel after you’ve used it to avoid spreading the virus to others.

When should I see my healthcare provider?

You should seek treatment for a cold sore if you have:

  • Eczema (also known as atopic dermatitis).
  • Numerous, frequent or extremely painful cold sores.
  • An outbreak that doesn’t clear up on its own within two weeks.
  • Sores on your eyes, hands, genitals or another part of your body.
  • HIV or cancer.
  • A compromised immune system, or if you’re getting chemotherapy or taking medication that weakens your immune system.

A note from Cleveland Clinic

Once you contract HSV-1, you have the virus for life. Some people will never develop a cold sore, but others will experience regular outbreaks. Once a cold sore starts, it has to run its course. Although it can be bothersome, it typically goes away on its own within two weeks. If you develop a cold sore and have a weakened immune system or eczema, talk to your healthcare provider. They’ll help you determine the best treatment option and avoid complications.

Medically Reviewed

Last reviewed on 04/27/2023.

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