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Canker and cold sores can be both painful and embarrassing. That’s why we’ve put together this guide to explain what causes them, what you can do to treat them and how MedExpress can help.


Canker and cold sores are quite common but that doesn't mean that they aren't annoying to deal with. While nearly everyone deals with them from time to time, some have triggers that can cause them more often than others. Here’s a guide to the causes, prevention and treatment of both of these issues.

What Causes Canker Sores?

1 out of 10 people deal with canker sores. Yet even the experts aren’t sure why one person will develop them and another won’t.1 Some of the factors that lead to increased canker sores include a family history, a weakened immune system, rubbing along the gumline from dentures or braces, hormonal changes and increased stress. Other reasons include injuries to the lining of the mouth, food allergies or not getting enough iron or Vitamin B in your diet.1

Many can get canker sores initially during their teen years. They are more common among women than examining mouth for sore

What are the symptoms? These mouth sores are round, white spots with red, slightly raised edges. They most often are on your lips and on the inside of your cheeks. They can also appear on your tongue, gums or the roof of your mouth.1

When a canker sore is forming, your mouth may burn or tingle. That pain may increase when eating hot or spicy or acidic food. They may also hurt more when you are chewing or talking.

Are they contagious? No, canker sores are not contagious.

Canker Sore Treatment

Canker sores can usually be diagnosed on your own. However, if they last for longer than two weeks, you should see your provider or dentist for an examination.

The good news? They often heal on their own without treatment. You can deal with the symptoms by using creams or mouthwashes that have anti-inflammatory or pain-relieving ingredients.

You should never attempt to pop a canker sore. If your mouth sore is causing great discomfort, visit your neighborhood MedExpress center to see a provider.

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Need a canker or cold sore treated? Schedule online or walk in any time from 8 to 8 every day.

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For your convenience, we accept most major insurance, most of which cover treatment for canker and cold sores. To verify that your insurance is in-network, visit the Plan Your Visit page. We also offer a discount to those patients who choose to pay in full for their visit at the time of service. Self-pay services are $199.

What Causes Cold Sores?

Contrary to their name, cold sores are not caused by the common cold. They are the result of the herpes simplex virus (HSV) or herpes type 1, which is carried by more than half of everyone in the U.S. from 14 to 49.2 Once you have this virus, you will have it for life.

Some will never get another cold sore, while others get them often. Often, cold sores are triggered by:2

  • Stress
  • Spending too much time in the sun
  • Fatigue
  • Having a cold, fever or the flu
  • An injury or cut
  • Post-dental work, cosmetic surgery or laser treatment
  • Food allergies
  • For women, getting their period

What are the symptoms? The initial exposure to the virus often happens in childhood, but it may rarely happen with adults. Initial symptoms last for one to two weeks and include:3

  • Cold and flu symptoms, like sore throat, painful swallowing, fever, headache, aches and pains and nausea
  • Swollen lymph nodes
  • A burning sensation in the mouth
  • Painful mouth sores that appear on the tongue, gums, lips or throat

After this initial infection, the virus moves to your nerves and stays there until it wakes up again. You may never get a cold sore again. If you do, it will probably not be as intense as the first infection.

The symptoms of a reoccurring cold sore are:3

  • Warning signs, including burning, itching or throbbing of the skin
  • Cold sores can spread to your eyes. You may become sensitive to light, feel pain or have runny eyes. If this happens, see a provider immediately.
  • If you touch your hand or your genitals after touching your cold sore, you may spread the virus. Wash your hands properly with hot water and soap for at least thirty seconds any time you touch your cold sore. If you don’t have access to soap and water, use a hand sanitizer that is at least 60 percent alcohol.

Are they contagious? Yes. Even when cold sores are properly treated, they can still spread to others. To avoid infecting anyone else, follow these precautions:4

  • Avoid kissing people, particularly children
  • Avoid close contact with anyone with weakened immune system
    • Newborn babies and children with eczema are very vulnerable
  • Don’t have any sexual relations until your symptoms have cleared up
  • Never share lip balm, makeup, towels or razors
  • Don't share your drink, food or eating utensils
  • As mentioned above, don't touch your cold sores without immediately washing your hands

You should also wash your hands repeatedly throughout the day. Use hot water and soap for at least thirty seconds any time you touch your cold sore. If you don't have access to soap and water, use a hand sanitizer that is at least 60 percent alcohol.

Cold Sore Treatment

Most cold sores will heal on their own.5 However, these tips will help speed the healing and reduce pain:

  • When a cold sore first appears, apply a cold sore over-the-counter medication that contains docosanol or benzyl alcohol
  • Place ice on the cold sore or gently suck on ice chips
  • Apply an over-the-counter pain relief gel that contains benzocaine, lidocaine, dibucaine or benzyl alcohol
  • Take acteaminophen or ibuprofen
  • Stay away from spicy and salty food
  • Place a clean, cold and wet compress on the sores for up to ten minutes
  • Apply petroleum jelly to the sores and any surrounding skin
  • Remember to properly wash your hands after touching your sores

If you have a known history of Herpes Simplex Virus and have had cold and canker sore outbreaks before, they may be stopped before they start. As soon as you feel a tingle where the outbreak normally occurs (such as on your lips), an antiviral medication can stop the outbreak from happening. This is important for special events such as a wedding or prom.

woman applying cream to mouth

Additionally, if you live with someone who is a immunologically compromised person (such as a newborn baby, an adult on chemotherapy or someone on chronic immunosuppressive therapy for psoriasis, rheumatoid arthritis or asthma) taking an antiviral medication will lower the risk of transferring the virus to them.

Remember: Any open or active blisters can shed and pass on the virus, but intact skin can also be infectious. Avoid touching any cold or canker sore and always wash your hands if you make any contact with them.

Otherwise, cold and canker sores only require treatment if they:

  • Become large in size
  • Interfere with eating or drinking
  • Show signs of infection

Your provider may treat them with a topical rinse or an antibiotic and steroid depending on the severity and origin of the cold sore. Additionally, if your cold sore is close to your eyes or has lasted more than two weeks, visit your neighborhood MedExpress for treatment.

There’s no need to be embarrassed about a canker or cold sore. Nearly everyone gets them and the care that you get from MedExpress will be centered on getting you back to feeling better fast.


  1. National Library of Medicine/National Center for Biotechnology Information. Canker sores (mouth ulcers). Last updated August 15, 2019. Accessed December 1, 2023.
  2. American Academy of Dermatology Association. Cold Sores: Who Gets and Causes. Accessed December 1, 2023.
  3. American Academy of Dermatology Association. Cold Sores: Signs and Symptoms. Accessed December 1, 2023.
  4. American Academy of Dermatology Association. Cold Sores: Overview. Accessed December 1, 2023.
  5. American Academy of Dermatology Association. Cold Sores: Tips for Managing. Accessed December 1, 2023.
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