The Basics of Mouth Sores

posted by Dr. Beau Beecher, DDS on 12/10/2021 in General

woman grimacing in pain and rubbing cheek due to mouth sore

Mouth sores often appear seemingly without notice, but they always manage to make their presence known. It's helpful to know the difference between the two most common types of sores, what causes them, and what to expect in terms of treatment.

What Causes Mouth Sores?

The specific cause of a mouth sore will vary depending on the type of sore. Causes of sores can range from a bacterial, viral, or fungal infection to the sharp edge of a broken tooth or filling. In some cases, even a loose orthodontic wire or poorly fitted denture can lead to the development of sores.

Certain foods, especially ones that are acidic, can also be contributing factors. While most mouth sores are common, some may be indicative of a more serious underlying disease. If you're wondering what might be causing pain in your mouth, here are the common causes of mouth sores:

Common Mouth Sore Causes

  • Biting your tongue, cheek, or lip
  • Burning your mouth
  • Experiencing irritation from a sharp object, such as braces, retainer, or dentures
  • Brushing your teeth too hard, or using a very firm toothbrush
  • Chewing tobacco

Uncommon Mouth Sore Causes

  • Over-the-counter or prescription medications
  • Gingivostomatitis
  • Infectious mononucleosis
  • Oral thrush
  • Hand, foot, and mouth disease
  • Radiation or chemotherapy
  • Autoimmune disorders
  • Bleeding disorders
  • Cancer
  • Celiac disease
  • Bacterial, viral, or fungal infection
  • Weakened immune system due to AIDS or a recent organ transplant

Types of Mouth Sores

There are many different types of mouth sores, and most materialize in different ways. Mouth sores can appear on the roof of your mouth, your gums, tongue, and even outside of your mouth. With that in mind, some mouth sore variants are common and relatively harmless, while others could indicate a severe illness. Let's explore some of the more common types of mouth sores:

Canker Sores 

Canker sores are the most common type of mouth sore. Whereas cold sores typically appear outside the mouth on the lips, canker sores are irritations that develop inside the mouth, most commonly in adolescents and young adults.

Science has yet to pinpoint the exact cause of canker sores. In terms of their appearance, canker sores tend to look like small lesions with a white or gray base and a red border. Furthermore, canker sores are not contagious, although fatigue, stress, and allergies are all believed to be factors that can increase the likelihood of a canker sore. In addition, if you bite your cheek or tongue, the cut can form a canker sore. If you’re wondering how you got a canker sore, here are some common causes that can make them appear:

Common Canker Sore Causes

  • Weakened immune system because of illness or stress
  • Hormone changes
  • Vitamin deficiency, especially of folate and B-12
  • Intestinal issues, such as Crohn's disease or irritable bowel syndrome (IBS)

Cold Sores

Cold sores are highly contagious. They appear on or around your lips as red blisters filled with fluid. Cold sores can often be painful, as well. Additionally, cold sores may also accompany flu-like symptoms. These symptoms can include a mild fever, body aches, and swollen lymph nodes. Cold sores are caused by the herpes simplex virus, or HSV, but before you start to panic, it's worth mentioning over 90% of people in the world have at least one form of HSV. 


Gingivostomatitis is a common infection of the mouth and gums. Usually found in children, the appearance of gingivostomatitis is similar to a canker sore, and is caused primarily by poor dental hygiene. Unlike a canker sore, however, the sores caused by gingivostomatitis aren't limited to the inside of the mouth. In fact, gingivostomatitis can create painful blisters on the lips, both on the inside and outside of the mouth. Gingivostomatitis can often cause drooling and pain when eating, although this is especially true among children.

Folate Deficiency

Folate deficiency can cause mouth sores as well. Folate is a B vitamin that’s important in the creation and repair of your body's DNA. Folate deficiency is most commonly seen in individuals with anemia or an otherwise low red blood cell count. Folate deficiency symptoms can include mouth sores, fatigue, pale skin, tongue swelling, graying hair, and growth delay.

Treatment Options for Mouth Sores

Both canker sores and cold sores will usually heal on their own within a week or two. There are topical anesthetics available over-the-counter, such as hydrogen peroxide, that may provide temporary relief. Additionally, pain relievers such as Tylenol can reduce swelling and help manage the pain caused by mouth sores. Generally speaking, you want to avoid hot and spicy foods and any food with a lot of sugar or salt, as they can further irritate your mouth sores. Additionally, avoid alcoholic beverages and tobacco for the same reasons.

Schedule An Appointment

If you have a mouth sore that has lasted longer than 14 days, schedule an appointment with your dentist as soon as possible. The dentists at Kimball & Beecher have extensive experience when it comes to dealing with mouth sores, and will make your comfort our priority. With six offices across Iowa, there's a dentist near you ready to help.

About The Author

Dr. Beau Beecher, DDS

Dr. Beau Beecher is the founder and CEO, of Kimball and Beecher Family Dentistry. Kimball and Beecher Family Dentistry is known for being a patient-centered practice that puts comfort and convenience first. Over 50,000 patients in Iowa cities travel miles to experience the high level of ... read more

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