Cold sores: Why you often get mouth sores or canker sores

Mouth sores are one of the most common oral health-related ailments among the population, not a serious but annoying lesion.

Mouth sores can appear on the inside of the cheeks, gums, roof of the mouth, lips and even the tongue, causing pain and discomfort in most patients.

Whether it's a recurring condition or a one-off, find out why the main types of sores occur and how to treat them.

What are sores?

A sore is a type of lesion that occurs on the inside of the oral mucosa. It is usually a small sore, as its size does not exceed 10 mm in most cases.

These sores appear on the inside of the cheeks, tongue, palate or gums, presenting a whitish colour that contrasts with the reddish tone of the mucosa.

They usually heal on their own in one or two weeks. However, in some cases it is necessary to apply a specific treatment, especially when several sores appear, or if they do not heal over time.

Why do canker sores appear?

The cause is still unknown. Its origin is multifactorial, linked to genetics and family history, and other predisposing factors may be trauma, stress, certain foods, hormonal imbalance and smoking.

Canker sores are more common in children, but also in adults with weakened immune systems. Some of the most common reasons for the development of canker sores in the mouth are trauma to the oral mucosa.

Small wounds caused by sharp objects, blows or bites inside the mouth are the most common causes of sores. Chafing from orthodontic appliances or ill-fitting dentures can also cause injuries that lead to canker sores.

Immunological factors

Many hypotheses have been put forward to link the immune system to canker sores. On the one hand, some authors argue for increased levels of immunoglobulins such as IgG, IgA and IgE; others speak of a possible cross-reactivity of oral mucosal antigens and bacterial antigens.


Viral infections, such as herpes or influenza, and even bacterial diseases, such as tonsillitis, have common symptoms such as fever, pain and inflammation of the throat and mouth tissues. In many cases, these symptoms are accompanied by mouth ulcers.


Stress can have a negative effect in many ways, as it can cause hormonal changes and affect general health. In addition, its possible effects on the immune system are a possible cause of canker sores.

Vitamin deficiency

The occurrence of canker sores has also been linked to dietary factors and nutritional deficiencies. According to one scientific study, a lack of folic acid, vitamin B12, vitamin A, vitamin E and vitamin C has been associated with canker sores. It also indicates that clinical improvements have been observed in patients with recurrent canker sores by excluding certain foods from their diet.

Depending on their cause and location, the best treatment for canker sores will differ. The aim is to prevent their recurrence by taking proper care of the oral mucosa, brushing teeth and visiting the dentist regularly.

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