Canker sores, also known as aphthous ulcers, are small ulcers in the mouth caused by various irritants. There are two main types of canker sores: simple canker sores and complex canker sores. Simple canker sores crop up a few times a year, lasting a few days to a week, while complex canker sores are rare, and crop up in people who have previously had canker sores. Complex canker sores may be accompanied by swollen lymph nodes, exhaustion and possibly fever. Canker sores are not contagious, but no one is quite sure what causes them.

Causes of Canker Sores

There is an old wive’s tale that canker sores are caused by eating too many tomatoes, but that isn’t always the case. As stated above, no one is quite sure what causes canker sores, but it is likely that there are many causes which all produce similar symptoms. Possibilities include:

  • Food allergies
  • Eating acidic foods such as lemons, oranges, strawberries, tomatoes, etc.  
  • Irritants in the mouth such as braces, dentures, or mouth piercings
  • Consistent stress
  • Underlying health conditions such as improper nutrition, celiac disease, impaired immune system, iron deficiency, etc.
  • Accidentally biting your cheek
  • Brushing your teeth too hard
  • Hormonal shifts
  • Family history of canker sores
  • And many more.

The Difference Between Canker Sores and Cold Sores

Although they are commonly mistaken for each other, cold sores and canker sores are very different. Cold sores are painful blisters caused by a viral infection, and they usually appear outside the mouth on the lips or under the nose  (canker sores tend to stay inside the mouth). Unlike canker sores, cold sores are very contagious, so you should avoid contact.

Healing a Canker Sore

If left alone, most canker sores heal within a few weeks, and any pain caused by a canker sore should subside within 10 days. However, if the pain is unusually strong, come in to the Silberg Center for Dental Science, your periodontist in Pittsburgh, and we can give you a prescription that may help, such as a mouth rinse, topical products (such as Benzocaine, Fluocinonide, or hydrogen peroxide), or oral medications; or we can provide cautery (burning) of the sore. Home remedies include: a baking soda or salt water rinse, avoiding spicy or acidic foods, applying ice to the wound, placing a whole clove on the infected area, or doing a hydrogen peroxide rinse.  

Preventing Canker Sores

The best way to prevent canker sores is to be careful of what you put in your mouth. Be careful not to eat foods that irritate your mouth, be gentle when brushing your teeth, eat healthy, and try to reduce your stress levels.

At the Silberg Center for Dental Science, we want to help you keep your mouth healthy and comfortable. While canker sores are not always avoidable, we’ll do whatever we can to make them bearable.


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