Causes of Mouth Sores and Treatments

Mouth sores are often caused by minor trauma. However, they can also be due to infection or systemic disease. Learn more about them in this article.
Causes of Mouth Sores and Treatments

Written by Carmen Martín

Last update: 27 May, 2022

You may not know the causes of mouth sores but surely you’ve had them at some point; people may also refer to them as “canker sores.” These lesions appear on the tissue that lines the oral cavity such as inside the cheeks and lips and on the gums.

Mouth sores are equally common and uncomfortable and increase sensitivity to many types of food. For example, drinking orange juice or hot drinks can be quite painful.

The location, shape, and causes of these lesions vary greatly. In fact, they could be caused by something as simple as an inner bite or a symptom of a more complicated systemic process. They could even be the first sign of an infection.

Today’s article will explain the main causes of mouth sores. We’ll also talk about the basic measures to treat them and heal them as soon as possible.

Causes of mouth sores

These lesions usually consist of a single round, whitish-colored lesion surrounded by an inflamed area. They’re seldom larger than 5/16 inches.

In addition, there’s often more than one sore and these are usually smaller than 1/8 inch. There are also cases where these lesions are larger, and healing is more complex.

A woman with canker sores.

These differences in size and number lie mainly in the cause. For example, as we’ve already mentioned, it’s normal to find a single wound due to a small bite. Other most frequent causes are:

  • Any treatment at the dentist’s, especially the use of orthodontics and braces
  • The herpes virus is often associated with multiple small mouth sores
  • Those due to stress and hormonal changes are more frequent in women as their hormonal alteration is more intense
  • Smoking may cause mouth sores due to a burn or even through the toxic additives that industrial cigarettes contain
  • Many drugs can cause them, especially those used for chemotherapy and radiotherapy against certain cancers

Systemic causes

In addition to the above-mentioned causes, there are numerous diseases that could lead to mouth sores. First of all, let’s emphasize that any nutritional deficiency can cause them. A lack of iron or vitamins, for example.

Another cause could be Behçet’s disease, whose main characteristic is the inflammation of the blood vessels. This is because it causes damage to different body organs and also manifests through wounds in the mouth.

Moreover, it’s common for those who experience inflammatory bowel disease to also encounter these lesions in their mouth. The same occurs with celiac disease. In addition, any pathology that causes wounds and blisters on the skin, such as pemphigus, could be the culprit.

Close up of a mouth sore.

Find out Why Do Canker Sores Appear?

How are mouth sores treated?

As you can see, most wounds are benign. This means they’ll resolve on their own and don’t usually require treatment. However, you must investigate the cause if they tend to recur and there are no obvious causes such as trauma.

While it’s true that there’s no reason to treat them, certain products do promote and speed up healing. For example, hyaluronic acid, marketed in creams and ointments. In addition, some types of food can irritate the wound further, so avoid them.

Also, the mouth sores may be due to infection so, in this case, you must treat them. The same goes for lesions that are a side effect of drugs. You should change your medicine in that case.

You can use mouthwashes containing anesthetics such as lidocaine if the discomfort is too intense. Those that contain corticosteroids can reduce inflammation.

Consult a doctor if the mouth sores are too bothersome or appear frequently. This is because they could be a symptom of some deficiency or disease that requires attention.


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This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.