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What Is the Difference Between a Cold Sore and a Canker Sore?

Both cold sores and canker sores develop in and around the mouth, so people often mix them up or aren’t sure which type of sore they have.

What Are Cold Sores?

Cold sores are caused by a herpes virus and are extremely contagious. These sores are small, fluid-filled blisters that often break soon after they appear, leak fluid, and then form scabs. Some people who get cold sores feel a tingling sensation shortly before a cold sore appears. The sores occur because of the presence of the herpes simplex virus 1, also called HSV-1, in the body. It is a different virus than what causes genital herpes, but both viruses remain in the body indefinitely.

After the initial exposure to HSV-1, a person typically has a more severe outbreak of herpes around the lips or other areas on the outside of the mouth. This outbreak may also include a fever or pain in the lymph nodes. After the first outbreak, future outbreaks are generally less severe but the virus remains in the nerves until something triggers it to migrate back to the mouth. Some of the most common triggers include:

  • Stress
  • Sun exposure
  • Surgery
  • Menstruation in women
  • Illness
  • Fevers
  • Fatigue.

Cold sores generally go away after one or two weeks on their own, although they can be very painful in the first few days.

What Are Canker Sores?

Canker sores are ulcers that appear on the inside of the mouth, often on the tongue, lips, and inside of the cheeks. The ulcer starts as a small bump, which then bursts within a day or two, leaving a yellow or white sore with a red border around the edge. Canker sores can appear alone or in clusters and can vary in size.

How to Tell Them Apart

While cold and canker sores might feel the same when the painful lesions appear in your mouth, they have slightly different symptoms. The signs of cold sores include:

  • Painful clusters of blisters on the lips, gums, tongue, and roof of the mouth, usually only on one side of the mouth.
  • Itching and burning at the sore sites.
  • Fluid oozing from the sores, which later become crusty.

Signs of canker sores include:

  • Small, painful ulcers on the tongue, roof of the mouth, and inside of the cheeks.
  • Tingling and burning at the sore sites.
  • Round lesions that are white or off-white with reddish borders.

One of the key differences between cold and canker sores is that canker sores typically only develop inside the mouth, whereas cold sores usually appear on the outside of the mouth, often around the lips.

The Causes of Cold vs. Canker Sores

Cold sores are typically caused by herpes simplex virus type 1. Because the sores are contagious, you can get the virus from kissing or engaging in oral sex with someone who has open sores. You can even get a cold sore if someone touches their own open sore and then touches you, as the virus is passed through sink-to-skin contact. Once you’re infected with the virus, you carry it for life.

Canker sores are not transmitted via any type of contact, nor are they contagious. Rather, they commonly result from situations or trauma, such as:

  • Biting your inner cheek or tongue
  • Rough dental work
  • Eating acidic or spicy foods
  • Smoking
  • Allergies
  • Trauma to the mouth
  • Nutritional deficiency
  • Hormonal changes.

Some people might be genetically predisposed to developing canker sores. Others experience outbreaks as a result of triggers. Those who have dry mouths often get more canker sores. In some situations, canker sores also indicate the presence of something more serious in the body, such as an autoimmune condition. Recurring canker sores have indicated that a person has celiac disease or another type of health disorder, so it’s important to contact a healthcare provider if you can’t get rid of your canker sores.

Both cold and canker sores resolve on their own within about a week or two.

How to Treat Cold Sores?

Although no cure is available for the herpes virus, you can treat the symptoms when you experience cold sores. Topical antiviral ointments and creams may shorten the healing process, although they often only do so when you apply them before the sore breaks out. For some people, using the ointment or cream after the sore has appeared can lessen pain. These topical treatments are available over the counter. Applying ice to the cold sore after it has appeared on the mouth can numb the area and lessen the pain as well.

Your healthcare provider may also prescribe you an oral antiviral medication to manage outbreaks of cold sores, especially if you have other health conditions, such as cancer, HIV/AIDS, or an autoimmune disorder. These medications are called famciclovir, acyclovir, and valacyclovir.

How to Treat Canker Sores?

Since the cause of canker sores can vary drastically between people, they are not as easy to treat. You can use over-the-counter pain medication or a numbing topical gel to treat the pain. For some, gargling with warm salt water or a solution of baking soda and water can shorten healing time and reduce pain as well. If your canker sore is making it difficult to eat or drink or lasts longer than two weeks, contact a healthcare provider.

Although both canker sores and cold sores cause pain and discomfort in the mouth, their causes are different. Canker sores are not contagious and usually appear as the result of a situation or trauma to the mouth, while cold sores are extremely contagious and occur because of the presence of the HSV-1 virus.

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