8 Potential Causes for Those Pesky Mouth Sores

Buckle up folks, because it’s time to talk about everyone’s favorite dinner table subject: mouth sores!

Okay, so we’re kidding. Mouth sores don’t exactly make for delightful conversation, nor are they a delightful experience. But they are common, so it’s important to familiarize yourself with their causes so you can more effectively identify what’s going on if a sore pops up in your mouth.

As the name implies, mouth sores can occur anywhere in or around the mouth—from the gums and inner cheeks to the tongue, lips, or roof of the mouth.

A quick notice! We hope you enjoy this blog, but please remember, it should NOT take the place of advice and consultation from a qualified dental professional (like the team at Rifkin Dental!). Please don't use content on the internet to self-diagnose — see your dental professional for regular check-ups and if you suspect you might have a chronic or acute dental issue.

Mouth sores can take several forms, but the most common are canker and cold sores. Different mouth sores have different symptoms and risks; some are simply annoying, while others require professional treatment.

There is no singular explanation for why mouth sores develop, and different people may be more or less susceptible to different causes. That being said, here’s a brief rundown of some of the most common causes of mouth sores.

Certain medical conditions

Some health issues that affect the intestines (such as Crohn’s disease, food sensitivities, and ulcerative colitis) may make people more susceptible to mouth sores. This makes sense when you consider the growing body of research linking the health of our mouths to the health of our guts.

Mouth sores may also arise due to allergies, autoimmune disorders, bleeding disorders, a weakened immune system, or (in rarer cases) oral cancer. Cold sores are caused by the herpes simplex virus.

Certain foods or beverages

Eating foods or beverages that are acidic, salty, and/or spicy can provoke irritation in the mouth. This irritation, in turn, can lead to mouth sores. (More on that below.)

Chewing tobacco

The use of chewing tobacco is strongly correlated with a greater susceptibility to mouth sores. So consider this one more reason to quit!

Hormonal changes

People of all genders experience natural hormonal shifts throughout the course of each month, and these changes may increase the likelihood of a person developing mouth sores. Same goes for the hormonal shifts experienced during pregnancy.


Many mouth sores are caused by a bacterial, fungal, or viral infection. In these cases, the infection prompts inflammation and an immune system response, which can account for the swelling at the site of the sore.


If a certain area of your mouth is persistently irritated (say, as a result of pointy braces, an improperly fitting denture, a sharp edge from a filling, eating the types of foods described above, or biting your cheek or tongue), this can lead to the development of a mouth sore.

Nutritional deficiencies

Consuming a diet that is low in certain vitamins and minerals may increase the likelihood of developing mouth sores. Deficiencies in vitamin B12 and/or folate are two common culprits.


This might seem like an unlikely cause—until you consider that stress provokes inflammation throughout the body. When inflammation is present, it increases the likelihood that small infections or irritations will turn into sores.

In many cases, mouth sores will go away on their own within a couple of weeks. However, if your mouth sore won’t go away, seems to be associated with an infection, or is accompanied by other symptoms such as fever or difficulty swallowing, it’s time to get checked out by a dentist.

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