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What Causes Mouth Ulcers?

Mouth ulcers may be small, but they can cause a surprising amount of discomfort. Eating, drinking, brushing your teeth, or even talking can become painful when a sore shows up inside your mouth. If you’ve ever dealt with recurring mouth ulcers, you may have wondered what causes them and whether there’s anything you can do to keep them from coming back. 

This guide breaks down what mouth ulcers are and why they happen. Learn more below!

Key Takeaways:

  • Mouth ulcers are common and can make everyday activities uncomfortable. 
  • They can be caused by injury, stress, diet, hormonal changes, or nutrient deficiencies. 
  • Most mouth ulcers heal on their own, but treatment can help reduce pain and speed up healing.

What Is a Canker Sore?

Mouth ulcers, also called canker sores, are small, shallow sores that form on the soft tissues inside your mouth. You’ll usually find them on the tongue, gums, inner cheeks, or the roof of the mouth. They’re often round or oval and may look white or yellow in the center with a red border. 

While mouth ulcers aren’t contagious, they can, unfortunately, be painful enough to interfere with daily life. For instance, eating crunchy foods or even brushing your teeth can irritate them and exacerbate symptoms. 


Symptoms of Mouth Ulcers

The most noticeable symptom of a mouth ulcer is pain, often described as burning or sharp, which typically worsens when eating, drinking, or talking. You may also notice redness or swelling around the sore. In some cases, a tingling or sensitive feeling may appear a day or two before the ulcer fully forms. 


What Causes Mouth Ulcers?

Mouth ulcers can develop for several reasons, and sometimes more than one factor is involved.

  1. Trauma or Injury

    2. One of the most common causes of mouth ulcers is minor injury to the mouth. Accidentally biting your cheek or tongue, brushing too hard, or irritation from braces or dental appliances can all damage the soft tissues and lead to a sore forming. 


  2. Nutritional Deficiences

    3. Low levels of certain vitamins and minerals can make you more prone to mouth ulcers. Deficiencies in vitamin B12, iron, or folic acid can affect how well your mouth tissues heal and how strong your immune system is. 


  3. Hormonal Changes

    4. Hormonal shifts can also play a role, especially for women. Some people notice mouth ulcers appearing during menstruation, pregnancy, or menopause, when hormone levels fluctuate. 


  4. Stress and Anxiety

    5. Stress doesn’t just affect your mood; it can also show up physically. Ongoing stress can weaken the immune system and make it easier for mouth ulcers to develop. Many people notice stores appearing during particularly stressful periods. 


  5. Food Sensitivities

    6. As mentioned above, certain foods can trigger mouth ulcers in some people. Spicy foods, acidic fruits like citrus, and even chocolate or coffee may irritate the mouth lining and lead to sores. 


  6. Viral Infections

    7. Some viral infections can cause mouth ulcers, particularly when the immune system is already run down. Illnesses like the flu or hand, foot, and mouth disease can result in painful sores inside the mouth.


Are There Different Types of Mouth Ulcers?

Yes, not all mouth ulcers are the same. Minor canker sores are the most common. They’re usually small and heal within one to two weeks without leaving a scar. Major canker sores are larger and deeper, which, as you probably guessed, means they’re more painful and take longer to go away. In some cases, they may leave scarring behind. 

Herpetiform canker sores appear as clusters of very small ulcers that can join together and create a large sore. Despite the name, they’re not caused by herpes. 


How Long Do Canker Sores Last?

The short answer is that it varies. Minor canker sores typically heal within 7-10 days, but major sores can take up to 2 weeks or longer to fully recover. If an ulcer lasts more than 2 weeks or continues to grow, consider seeing a dentist. 


Canker Sores vs. Cold Sores

While both can cause discomfort inside the mouth, cold sores are caused by the herpes simplex virus (HSV) and typically appear outside the mouth, usually around the lips. Canker sores, on the other hand, are non-contagious and develop inside the mouth, often on the tongue or inner cheeks. Cold sores also tend to crust over, while canker sores don’t. 


How Are Canker Sores Different from Oral Cancers? 

Oral cancer sores are typically larger and may bleed. If you notice a sore in your mouth that hasn’t healed after several weeks, has irregular edges, or is accompanied by other symptoms like difficulty swallowing, get it checked by your dentist or doctor as soon as possible. You can learn more about other symptoms of oral cancer here. 


How to Prevent Canker Sores

While it’s not always possible to prevent mouth ulcers completely, a few habits can lower your risk, including, but not limited to:

  • Maintain Good Oral Hygiene: Using a soft-bristle toothbrush and brushing gently can help protect the tissues in your mouth. Flossing daily also helps remove bacteria and food particles that may contribute to irritation. 
  • Avoid Trigger Foods: If you notice that certain foods tend to trigger ulcers, try limiting or avoiding them. Softer, less acidic foods can reduce irritation while a sore is healing. 
  • Stay Hydrated: Drinking plenty of water helps keep your mouth moist and reduces dryness, which could make irritation worse. 

When to See a Dentist for Mouth Ulcers

You should see a healthcare professional if an ulcer lasts longer than two weeks, keeps getting larger, or is extremely painful. Ulcers that are accompanied by a fever or other symptoms could also be signs of an underlying issue that needs medical attention. 


Concerned About a Canker Sore? Give Our Office a Call Today!

If you’re dealing with frequent or painful mouth ulcers, you’re not alone! While they’re usually harmless and tend to go away on their own, if you’re ever concerned about a canker sore, especially if it doesn’t seem to heal or worsens over time, please call 732-714-1030 or contact our Point Pleasant office today to schedule an appointment. 

About the Author: Dr. Joseph Zicchino provides a wide array of cosmetic dentistry services, including Invisalign® Clear Aligners, at his practice in Point Pleasant, NJ. He earned his dental degree from NYU Dental School and established Coastal Dental Group in 2004. For more information or to schedule an appointment, call (732) 714-1030!