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Mouth Sores

Most of us have suffered some form of mouth sore. That annoying little spot inside the mouth along the gum line, or on the inside of the cheek that makes itself known in a vicious way when you eat a spicy, or acidic kind of food. Maybe we get a little blister on our lip or in the corner of our mouth. Sometimes they present as a tiny white spot, or a nasty looking red welt. Many of us have referred to them as just a mouth sore and we find simple topical ointments to soothe the irritation at the local drugstore. But what are they really? What causes them?

Mouth Sore #1: Canker Sores

What is a Canker Sore?

The medical definition of a canker sore is a small, shallow ulcer that appears in the mouth that can make eating and talking uncomfortable. There are two types of this mouth sore.  Neither type are contagious.


Simple canker sores can appear up to 4 times a year and last up to a week, typically found in people between the ages of 10 and 20 years old.


Complex canker sores are less common and happen more frequently in people who have had them in the past.

What Causes Canker Sores?

The simple truth is, the cause of this mouth sore is still not known. A simple canker sore is thought to be caused by any number of things: stress, tissue injury (such as a sharp tooth surface rubbing on the inside of the cheek or an oral appliance rubbing on the gums/tongue) or acidic foods (such as lemons, oranges, pineapple and tomatoes). However a complex canker sore can be caused by an underlying health condition, such as a nutritional deficiency, an impaired immune system or certain gastrointestinal tract diseases such as Crohn’s disease.

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What are the Symptoms of a Canker Sore?

A painful mouth sore on the inside of the mouth on the tongue, gums, soft palate or inside the cheek.  Many people typically report a tingling or burning sensation prior to the appearance of the canker sore.  The sores will appear round, white or gray in color and have a red edge.  However, In the case of some complex canker sores, one might even experience a fever and swollen lymph nodes.  If you develop a mouth sore along with these symptoms contact your doctor.

Mouth Sore #2: Cold Sores

Cold sores (also referred to as fever blisters) are painful infections caused by the herpes simplex virus (HSV). Once in your system, these particular mouth sores can be triggered by certain foods, sunburn, stress, fever, colds, allergies or menstruation. The blisters may show up anywhere on your body, but are most commonly found on the outside of your mouth and lips, your nose, cheeks and fingers. The blister forms, breaks, and oozes, crust over, and eventually slough off to reveal new skin. These sores usually last 7-10 days and are contagious until they crust over completely.

Almost 90% of all people get a cold sore at some point in their life, however, after the first infection, antibodies are typically developed and most people never get a cold sore again. Cold sores are not normally life threatening, however, people with drastically depressed immune systems from a physical disorder, disease or medication can develop serious complications.

What Causes Cold Sores?

The Herpes Simplex Virus. How does one get that very nasty little virus? Through contact with someone who is infected. As this mouth sore is a virus, if the infected person is not currently showing signs of the infection (the virus is lying in a dormant state) they are not contagious. However, if they do have a blister on their lip, avoid kissing them for a while, as well as eating from the same utensils or sharing a face towel. Don’t worry though, as only about 40% of people who do contract the virus have repeated cold sores.

What are the Symptoms of a Cold Sore?

After the initial exposure, these mouth sores can take a while to develop – sometimes up to 20 days!  A couple days before the blisters form, you might experience sensitivity and/or itching.  Some people even describe the feeling as a tingling, and state they can even sometimes feel their heartbeat in the area.

Treatment for Canker and Cold Sores

The pain from a canker sore usually lessens within a few days and the sores heal without treatment. If the sores are large, painful and persistent, your dentist may prescribe an antimicrobial mouth rinse or ointment to relieve the irritation. It is also suggested that you avoid foods that irritate your mouth such as citrus fruits, acidic vegetables and spicy flavors.  Be sure to brush with a soft-bristled toothbrush and floss daily, which will keep your mouth free from irritating food particles.

Cold sores also typically heal on their own.  However, if they are painful or you are embarrassed by their appearance, over the counter topical ointments and creams can be used. The virus that causes the cold sore, unfortunately, can not be cured.

Thankfully, though they are both annoying and painful mouth sores, neither are life threatening and can happen to anyone.  If you think you have one of these mouth sores and need advice on treatment, call our office today to schedule a quick appointment so your dentist can help treat your mouth sore.

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